The complete library
Free calculator library
Search 663 free, ungated calculators spanning 42 categories, from loans and taxes to health, math and home projects. Every result shows its formula, a worked example, limitations, and sources — nothing hidden behind a sign-up, nothing stored on a server.
How the library is built
Calculators by category
The largest categories by number of calculators. Use the search below to jump straight to a tool, or browse a category from the menu.
- Business Finance62 calculators
- Investing & Returns55 calculators
- Retirement48 calculators
- Mortgage & Home45 calculators
- Geometry30 calculators
- Household & Life24 calculators
- Taxes & Paycheck22 calculators
- Algebra & Arithmetic22 calculators
- Real Estate Investing19 calculators
- Unit Conversion19 calculators
- Auto Finance18 calculators
- Education & Student Loans18 calculators
- Home & Construction17 calculators
- Bonds & Fixed Income16 calculators
- Science & Electronics16 calculators
- Loans & Payments15 calculators
- Debt & Credit14 calculators
- Startup & SaaS14 calculators
- Physics & Mechanics14 calculators
- Freelance & Self-Employed13 calculators
- Statistics & Probability13 calculators
- Everyday Money12 calculators
- Body Composition11 calculators
- Savings & Banking9 calculators
- Energy & Nutrition9 calculators
- Clinical Estimates9 calculators
- Number Theory & Precision9 calculators
- Time & Clock8 calculators
- Energy & Utilities8 calculators
- Lawn & Garden8 calculators
- Fitness & Performance7 calculators
- Networking & Technology7 calculators
- Date & Time6 calculators
- Plumbing6 calculators
- Carpentry6 calculators
- Craft & Sewing6 calculators
- Weather5 calculators
- HVAC5 calculators
- Electrical Trade5 calculators
- Concrete & Masonry5 calculators
- Machining4 calculators
- Cooking & Kitchen4 calculators
Loans & Payments
Compare payments, borrowing costs, terms and payoff strategies.
Loan Payment Calculator
Calculate the monthly payment and total interest for a fixed-rate installment loan.
Loan Affordability Calculator
Reverse-calculate a possible loan amount from a payment limit, rate and term.
Loan Payoff Calculator
Estimate payoff time and remaining interest at a fixed monthly payment.
Simple Interest Calculator
Calculate interest and ending balance when interest does not compound.
APR Calculator
Estimate APR by including upfront finance charges in a fixed-payment loan.
Loan Comparison Calculator
Compare payment and lifetime interest for two loan offers.
Balloon Loan Calculator
Estimate payment and interest for a loan with a final lump-sum balance.
Amortization Schedule Calculator
Build a payment-by-payment loan amortization schedule.
Personal Loan Calculator
Estimate personal-loan payments and lifetime interest.
Boat Loan Calculator
Estimate boat financing payments and total interest.
Loan Interest Rate Calculator
Reverse-solve the annual rate implied by principal, payment and number of payments.
Loan Term Calculator
Reverse-solve payoff months from principal, annual rate and monthly payment.
Loan Origination Fee Calculator
Calculate origination fee, net proceeds and total modeled borrowing cost.
Loan Prepayment Penalty Calculator
Estimate a contractual prepayment charge and net interest savings.
Installment Loan Calculator
Calculate fixed payment, interest and total cost for a standard installment loan.
Mortgage & Home
Estimate affordability, monthly ownership cost, equity and refinance tradeoffs.
Mortgage Payment Calculator
Estimate principal, interest, property tax, insurance and HOA in one monthly figure.
Home Affordability Calculator
Estimate a home-price range from income, debts, down payment and mortgage assumptions.
Closing Cost Calculator
Estimate variable and fixed closing charges plus cash needed with 20% down.
Mortgage Refinance Calculator
Estimate monthly savings and time needed to recover refinance costs.
Extra Mortgage Payment Calculator
Estimate interest saved and months removed by adding principal each month.
Mortgage Points Calculator
Calculate how long payment savings take to recover discount points.
Loan-to-Value Calculator
Calculate mortgage loan-to-value and estimated property equity.
Rent Affordability Calculator
Estimate a rent budget from income and recurring housing costs.
Rent vs. Buy Calculator
Compare estimated renting costs with ownership costs and equity.
Mortgage Recast Calculator
Estimate the new payment after a lump-sum principal reduction and recast.
Biweekly Mortgage Calculator
Estimate interest and time saved with 26 half-payments per year.
15 vs. 30 Year Mortgage Calculator
Compare monthly payments and total interest across two mortgage terms.
Fixed vs. ARM Calculator
Estimate an adjustable-rate mortgage reset payment under cap assumptions.
ARM Adjustment Cap Calculator
Model a first ARM reset using index, margin and adjustment cap.
Interest-Only Mortgage Calculator
Compare the interest-only payment with the later amortizing payment.
Jumbo Mortgage Calculator
Estimate payments and interest on a larger mortgage balance.
PMI Calculator
Estimate monthly private mortgage insurance and equity needed for a target LTV.
2-1 Buydown Calculator
Estimate the subsidy and first-year payment savings for a temporary 2-1 buydown.
HELOC Payment Calculator
Estimate draw-period and repayment-period HELOC payments.
Home Equity Borrowing Calculator
Estimate equity and potential borrowing capacity at a selected combined LTV.
Seller Concession Calculator
Estimate the usable seller credit under an entered cap and eligible costs.
True Cost of Homeownership Calculator
Combine financing, taxes, insurance, HOA and maintenance reserve.
Home Maintenance Reserve Calculator
Estimate a monthly maintenance reserve as a percentage of home value.
10-Year Mortgage Calculator
Calculate payment, total interest and total scheduled payments for a 10-year mortgage.
15-Year Mortgage Calculator
Calculate payment, total interest and total scheduled payments for a 15-year mortgage.
20-Year Mortgage Calculator
Calculate payment, total interest and total scheduled payments for a 20-year mortgage.
30-Year Mortgage Calculator
Calculate payment, total interest and total scheduled payments for a 30-year mortgage.
FHA Mortgage Insurance Calculator
Calculate an FHA-style financed loan, upfront MIP, monthly MIP and estimated total payment.
FHA Loan Calculator
Estimate an FHA loan amount, upfront and annual mortgage insurance, and total monthly housing payment.
VA Funding Fee Calculator
Calculate a VA-style funding fee, financed balance and estimated total monthly payment.
VA Loan Calculator
Estimate a VA financed balance, funding fee and total monthly housing payment.
USDA Guarantee Fee Calculator
Calculate a USDA-style upfront fee, annual fee and estimated monthly payment.
USDA Loan Calculator
Estimate a USDA loan balance, upfront guarantee fee, annual fee and total monthly housing payment.
Mortgage APR Calculator
Estimate mortgage APR from note rate, term and APR-included finance charges.
Down Payment Calculator
Calculate down payment, loan amount and total cash needed with closing costs and reserves.
Home Equity Loan Calculator
Calculate a fixed home-equity payment, total interest and combined loan-to-value.
HELOC vs. Home Equity Loan Calculator
Compare a modeled interest-only HELOC with a fixed-rate home-equity loan.
Mortgage Escrow Shortage Calculator
Estimate a new escrow payment after projected bills and a repayable shortage.
Assumable Mortgage Calculator
Estimate the cash gap, secondary financing and combined payment for an assumable mortgage.
Mortgage Points vs. Down Payment Calculator
Compare using the same cash for discount points or a larger down payment.
Cash-Out Refinance Calculator
Estimate cash received, new loan amount and payment at a target loan-to-value.
Bridge Loan Calculator
Estimate interest-only payment, fees and payoff for short-term bridge financing.
Reverse Mortgage Proceeds Calculator
Estimate gross principal limit and net proceeds from an entered principal-limit factor.
Mortgage Payoff Calculator
Reverse-solve mortgage payoff time, total remaining interest and payoff total from a chosen payment.
Canadian Mortgage Calculator
Calculate a Canadian mortgage payment with half-yearly compounding from the price, down payment, rate and amortization.
Investing & Returns
Model compounding, growth, income and investment returns.
Compound Interest Calculator
Project future value from a starting investment, monthly contributions and return.
Investment Return Calculator
Calculate total investment return and net gain including cash income.
CAGR Calculator
Convert beginning and ending values into a compound annual growth rate.
Future Value Calculator
Estimate what a present lump sum could grow to at a constant return.
Present Value Calculator
Estimate the amount needed today to reach a future target.
Dollar-Cost Averaging Calculator
Project the future value and estimated growth of equal monthly investments over time.
Dividend Yield Calculator
Calculate dividend yield and annual income from price, dividend and shares.
IRR Calculator
Estimate internal rate of return from an initial outlay and five annual cash flows.
MIRR Calculator
Estimate a modified internal rate of return from future inflows and present outflows.
Annualized Return Calculator
Convert a multi-year total change into a compound annualized rate.
Money-Weighted Return Calculator
Estimate the return implied by timed cash flows.
Time-Weighted Return Calculator
Estimate a normalized compound return across a holding period.
Investment Fee Drag Calculator
Estimate long-term value lost to an annual investment fee.
Expense Ratio Cost Calculator
Estimate the compounded cost of an annual fund expense ratio.
Dividend Growth Calculator
Project annual dividend income under a constant growth assumption.
Stock Profit Calculator
Calculate net stock gain or loss after trading fees.
Stock Average Cost Calculator
Measure profit or loss against an entered average purchase price.
Portfolio Rebalancing Calculator
Calculate the trade needed to return one holding to its target weight.
Asset Allocation Drift Calculator
Compare a holding’s current portfolio weight with its target.
Sharpe Ratio Calculator
Estimate excess return per unit of volatility.
Sortino Ratio Calculator
Estimate excess return per unit of downside deviation.
Maximum Drawdown Calculator
Calculate peak-to-trough loss and the gain needed to recover.
Tax-Loss Harvesting Calculator
Estimate current tax benefit and remaining loss carryforward.
Rule of 72 Calculator
Estimate doubling time from an annual return assumption.
XIRR Calculator
Estimate an annualized return from irregularly timed cash flows.
Investment Payback Period Calculator
Calculate simple and discounted payback periods from recurring cash inflow.
Average Investment Return Calculator
Calculate arithmetic, geometric and cumulative return from five annual returns.
After-Tax Investment Return Calculator
Estimate ending value, tax on gains and after-tax annualized return.
Mutual Fund Return Calculator
Estimate an after-fee, after-tax fund ending value across a holding period.
ETF Fee Calculator
Estimate compounded annual fee drag on an ETF investment.
DCA vs. Lump Sum Calculator
Compare investing cash immediately with deploying the same amount over time.
Dividend Reinvestment Calculator
Compare modeled values with dividends reinvested or taken as cash.
Investment Beta Calculator
Calculate beta from covariance and market variance and estimate CAPM return.
Investment Alpha Calculator
Estimate alpha relative to a CAPM expected return.
Investment Volatility Calculator
Annualize periodic standard deviation and compare return with volatility.
Asset Correlation Calculator
Calculate correlation from covariance and two asset standard deviations.
Portfolio Weighted Return Calculator
Calculate expected portfolio return from three asset weights and returns.
Two-Asset Portfolio Risk Calculator
Estimate portfolio volatility from weights, asset volatility and correlation.
Investment Withdrawal Calculator
Project ending balance, total withdrawals and years funded under inflation-adjusted withdrawals.
Stock Split Calculator
Calculate theoretical shares and price after a forward or reverse split.
Crypto Profit Calculator
Calculate gain and return using purchase cost, sale proceeds and fees.
Rule of 115 Calculator
Estimate the time required to triple money at a constant annual return.
P/E Ratio Calculator
Calculate a stock's price-to-earnings ratio and earnings yield from its price and earnings per share.
PEG Ratio Calculator
Calculate the PEG ratio by dividing the P/E ratio by expected earnings growth.
Dividend Payout Ratio Calculator
Calculate the share of earnings paid out as dividends and the share kept in the business.
Earnings Per Share (EPS) Calculator
Calculate earnings per share from net income, preferred dividends and average shares outstanding.
Market Cap and Enterprise Value Calculator
Calculate market capitalization and enterprise value from share price, shares, debt and cash.
Book Value Per Share Calculator
Calculate book value per share and the price-to-book ratio.
Graham Number Calculator
Calculate the Graham number and the margin of safety at the current price.
Option Profit Calculator
Calculate the profit, break-even price and return on a call or put option at expiration.
Position Size Calculator
Calculate how many shares to buy from account size, risk per trade and stop distance.
Risk Reward Ratio Calculator
Calculate the reward-to-risk ratio and the win rate needed to break even on a trade.
Kelly Criterion Calculator
Calculate the Kelly fraction of a bankroll to risk from your win chance and payoff.
Net Present Value (NPV) Calculator
Calculate the net present value and profitability index of an investment from its cash flows and discount rate.
Continuous Compounding Calculator
Calculate the balance when interest compounds continuously, with the effective annual rate.
Retirement
Translate future spending into portfolio, contribution and income targets.
Retirement Savings Calculator
Project an existing retirement balance plus monthly contributions.
Retirement Goal Calculator
Estimate the portfolio required to cover a retirement spending gap.
401(k) Employer Match Calculator
Calculate employee and employer contributions under a simple match formula.
IRA Growth Calculator
Project IRA growth from a current balance and ongoing contributions.
FIRE Number Calculator
Estimate a financial-independence portfolio from spending and withdrawal rate.
Retirement Withdrawal Calculator
Estimate first-year income from portfolio withdrawals plus fixed income.
Retirement Income Gap Calculator
Compare desired spending with fixed income and portfolio withdrawals.
RMD Calculator
Calculate a required minimum distribution from an entered IRS factor.
Inherited IRA RMD Calculator
Estimate a distribution from an inherited IRA using an entered factor.
QCD Tax Savings Calculator
Estimate tax avoided when a qualified charitable distribution replaces taxable RMD income.
Roth Conversion Calculator
Estimate current conversion tax and a projected future tax-rate advantage.
Roth Conversion Bracket-Fill Calculator
Estimate available room in a chosen tax bracket.
Backdoor Roth Pro-Rata Calculator
Estimate the taxable share of a conversion under the IRA pro-rata rule.
Traditional vs. Roth IRA Calculator
Compare modeled after-tax future values under current and future tax rates.
Social Security Break-Even Calculator
Estimate the age when a higher delayed benefit catches up with earlier claiming.
Pension Lump Sum vs. Annuity Calculator
Compare a pension stream’s present value with a lump-sum offer.
Early 401(k) Withdrawal Cost Calculator
Estimate cash received and future growth forgone after tax and penalty.
Medicare IRMAA Cliff Calculator
Measure distance to an entered IRMAA threshold and annual surcharge exposure.
Retirement Healthcare Cost Calculator
Project first-year and simple lifetime healthcare costs.
FIRE Calculator
Estimate a financial-independence target and years to reach it.
Lean FIRE Calculator
Estimate a target from a lean annual spending plan.
Fat FIRE Calculator
Estimate a target from a higher retirement spending plan.
Coast FIRE Calculator
Estimate the invested amount needed today to grow to a future target without new contributions.
Retirement Income Tax Calculator
Estimate spendable income from taxable, tax-free and fixed retirement income.
Retirement Monte Carlo Calculator
Stress-test a retirement withdrawal plan across 101 deterministic return paths.
Sequence of Returns Risk Calculator
Compare an identical market loss early versus late in a retirement withdrawal horizon.
72(t) SEPP Calculator
Estimate annual substantially equal periodic payments using two simplified methods.
Mega Backdoor Roth Capacity Calculator
Estimate potential after-tax plan contribution room below an entered overall limit.
Annuity Growth Calculator
Project an annuity’s future value from a starting balance and monthly contributions.
Annuity Payout Calculator
Estimate a level monthly payout, total payouts and modeled interest component.
Annuity Present Value Calculator
Calculate the present value of a level monthly annuity payment stream.
Immediate Annuity Calculator
Estimate a level payout from an amount annuitized over a selected period.
Social Security Claiming Age Calculator
Compare cumulative benefits from claiming at 62, full retirement age or 70.
Social Security Spousal Benefit Calculator
Estimate a potential spousal amount, top-up and combined household benefit.
Taxable Social Security Benefits Calculator
Estimate provisional income and the federal taxable share of Social Security benefits.
Multi-Year RMD Calculator
Project first-year and cumulative RMDs with a declining entered factor and balance growth.
First-Year RMD Timing Calculator
Estimate the income effect of taking a delayed first RMD and second RMD in the same year.
Retirement Withdrawal Order Calculator
Model taxable-first, tax-deferred-second and Roth-last withdrawals.
Required Retirement Contribution Calculator
Calculate annual and monthly employee saving needed to reach a retirement target.
Barista FIRE Calculator
Estimate the portfolio target after part-time and other dependable income.
Pension COLA Calculator
Project a pension’s final-year payment and cumulative income with an annual COLA.
401(k) Contribution Calculator
Calculate employee, employer and unused overall plan contribution capacity.
403(b) Contribution Calculator
Calculate employee, employer and unused overall 403(b) plan capacity.
Roth IRA Contribution Calculator
Project the value, growth and current after-tax cash cost of an eligible Roth IRA contribution.
Traditional IRA Deduction Calculator
Estimate the current tax effect of a fully or partially deductible IRA contribution.
Inherited IRA 10-Year Distribution Calculator
Estimate a level annual withdrawal across an entered inherited-account distribution window.
Long-Term Care Cost Calculator
Project first-year and total long-term-care costs after inflation.
Early Retirement Health Insurance Calculator
Estimate the healthcare funding bridge between retirement and Medicare eligibility.
Savings & Banking
Plan savings goals, reserves, yields, CDs and time to goal.
Savings Growth Calculator
Project account growth from an opening balance and monthly deposits.
Savings Goal Calculator
Calculate the monthly deposit needed to reach a future balance.
APY Calculator
Convert a nominal rate and compounding frequency into effective annual yield.
CD Savings Calculator
Estimate CD maturity value and interest from rate, term and compounding.
Emergency Fund Calculator
Estimate a reserve target from essential expenses and months of coverage.
Time to Save Calculator
Estimate months needed to reach a goal with regular deposits and growth.
Required Interest Rate Calculator
Calculate the annual return a lump sum needs to reach a target.
CD Ladder Calculator
Divide savings across CD maturity rungs and estimate interest.
Millionaire Calculator
Estimate years, contributions and growth required to reach a target balance.
Debt & Credit
Understand payoff time, interest, utilization and consolidation.
Credit Card Payoff Calculator
Estimate payoff time and interest for a card balance and fixed payment.
Credit Card Interest Calculator
Estimate monthly card interest and the share of your payment that reduces principal.
Balance Transfer Calculator
Estimate promotional-period balance and savings after transfer fees.
Debt Consolidation Calculator
Compare a consolidation loan with current weighted debt.
Credit Utilization Calculator
Calculate revolving utilization across balances and limits.
Debt-to-Income Calculator
Calculate required monthly debt as a share of gross monthly income.
Debt-Free Date Calculator
Estimate months remaining on fixed-rate debt at a chosen payment.
Credit Card Minimum Payment Calculator
Estimate payoff time when payments follow a percentage-based minimum.
Credit Card Payment Calculator
Calculate the monthly payment required to clear a balance by a target date.
Debt Payoff Date Calculator
Calculate the payment required for a chosen payoff horizon.
Debt Snowball vs. Avalanche Calculator
Simulate highest-rate-first and smallest-balance-first payoff strategies across three debts.
Debt Avalanche Calculator
Calculate payoff time and compare interest with a smallest-balance-first strategy.
Debt Snowball Calculator
Calculate payoff time and compare interest with a highest-rate-first strategy.
Rule of 78 Calculator
Calculate the interest refund when a precomputed loan is paid off early under the Rule of 78.
Taxes & Paycheck
Create educational estimates for federal tax and take-home pay.
2026 Federal Income Tax Calculator
Estimate 2026 U.S. ordinary income tax using published brackets and deductions.
Take-Home Pay Calculator
Estimate annual and monthly take-home pay after entered deductions.
Self-Employment Tax Calculator
Estimate self-employment tax from net profit and an entered rate.
Capital Gains Tax Calculator
Estimate taxable gain and tax from proceeds, basis, costs and rate.
Sales Tax Calculator
Calculate sales tax and final price from a pre-tax amount and rate.
Property Tax Calculator
Estimate annual and monthly property tax from value and local assumptions.
Tax-Equivalent Yield Calculator
Convert a tax-exempt yield into a comparable taxable yield.
State Income Tax Calculator
Estimate state income tax using a state-specific deduction and rate you enter.
State Retirement Income Tax Calculator
Estimate state tax on Social Security, pension, retirement withdrawals and other income.
State Estate Tax Calculator
Estimate state estate tax from an entered exemption, deductions and tax rate.
Inheritance Tax Calculator
Estimate inheritance tax from the transfer value, applicable exemption and entered rate.
Bonus Take-Home Calculator
Estimate net bonus and withholding from entered federal, state and payroll rates.
Overtime Pay Calculator
Calculate weekly and annual gross pay using regular and overtime hours.
Paycheck Calculator
Estimate gross pay, deductions and net pay for any pay frequency.
Marriage Tax Penalty or Bonus Calculator
Compare a simplified joint federal estimate with two single-filer estimates.
QBI Deduction Calculator
Estimate a simplified qualified business income deduction and tax effect.
Tax Withholding Calculator
Project full-year withholding and a potential refund or balance due.
Tax Refund or Amount Due Calculator
Compare projected tax with full-year withholding to estimate refund or balance.
Federal Estate Tax Calculator
Estimate taxable estate and federal estate tax using an entered exemption and rate.
Reverse Sales Tax Calculator
Find the price before tax and the tax amount from a total that already includes sales tax.
Gross Pay Calculator
Calculate gross pay per period and per year from an hourly rate, regular hours and overtime.
PTO Accrual Calculator
Calculate paid time off earned per pay period and the balance available so far.
Auto Finance
Compare vehicle payments, leases, depreciation and running costs.
Auto Loan Calculator
Calculate monthly payment and total interest on a vehicle loan.
Auto Affordability Calculator
Estimate an affordable amount financed from payment, rate and term.
Auto Lease Calculator
Estimate a lease payment from capitalized cost, residual and money factor.
Lease vs. Buy Calculator
Compare lease outlay with purchase payments and resale value.
Auto Depreciation Calculator
Estimate future vehicle value at a constant annual depreciation rate.
Auto Refinance Calculator
Estimate payment savings and fee break-even from a lower loan rate.
Fuel Cost Calculator
Estimate monthly and annual fuel spending from miles, economy and price.
Auto Negative Equity Calculator
Calculate negative equity and a replacement vehicle’s starting financed amount.
Vehicle Total Cost of Ownership Calculator
Combine depreciation, interest, fuel, insurance, maintenance and fees.
Lease Mileage Calculator
Calculate total allowed miles, excess miles and expected mileage charges.
Lease Money Factor Calculator
Convert a lease money factor to approximate APR and back again.
Car Sales Tax & Fees Calculator
Estimate taxable price, sales tax and drive-out price after trade credit and incentives.
EV vs. Gas Fuel Savings Calculator
Compare annual gasoline and electricity costs and premium payback.
20/4/10 Car Affordability Calculator
Test 20% down, a four-year payment and a 10% gross-income transportation target.
Auto Loan Payoff Calculator
Reverse-solve auto-loan payoff time, remaining interest and payoff total from a monthly payment.
Trade-In Equity Calculator
Calculate trade equity or negative equity and its effect on replacement financing.
Cash Back vs Low Interest Calculator
Compare taking a cash-back rebate with your own loan against the dealer's low promotional rate.
Trip Cost Calculator
Estimate the fuel and total cost of a road trip, and each traveler's share.
Real Estate Investing
Evaluate rental income, operating performance and leverage.
Cap Rate Calculator
Calculate rental capitalization rate from income, vacancy, expenses and value.
Cash-on-Cash Return Calculator
Calculate annual cash flow as a percentage of cash invested.
Rental Cash Flow Calculator
Estimate cash flow after vacancy, operating costs and debt service.
Net Operating Income Calculator
Calculate property NOI and operating expense ratio before financing.
DSCR Calculator
Calculate debt-service coverage and cash flow after loan payments.
Gross Rent Multiplier Calculator
Calculate property price as a multiple of annual gross rent.
Break-Even Occupancy Calculator
Calculate occupancy needed to cover operating costs and debt service.
Rental Property ROI Calculator
Combine cash flow, principal paydown and appreciation relative to cash invested.
House Flip Calculator
Estimate flip profit, return on cost and a target maximum purchase price.
BRRRR Calculator
Estimate refinance proceeds, cash left in the deal and post-refinance cash return.
Rental Property Depreciation Calculator
Estimate depreciable basis, annual depreciation and a simplified tax effect.
1031 Exchange Boot Calculator
Estimate realized gain, replacement equity and potential taxable boot.
Price per Square Foot Calculator
Calculate property price per square foot and compare with a benchmark.
Rent Increase Calculator
Calculate new rent, effective rent and annual revenue change.
Rental Vacancy Loss Calculator
Calculate potential rent, vacancy loss and effective rental income.
Property Management Fee Calculator
Estimate management, leasing and fixed fees as a share of rent.
Rental Yield Calculator
Calculate gross and net rental yield from price, annual rent and expenses.
1% Rule Calculator
Check whether a rental's monthly rent reaches 1 percent of its price, and the shortfall if not.
Land Acreage Calculator
Calculate the acres in a rectangular lot from its length and width in feet.
Business Finance
Calculate margins, break-even volume, liquidity and runway.
Gross Margin Calculator
Calculate gross profit and margin from revenue and cost of goods sold.
Markup Calculator
Calculate markup on cost and gross profit per unit from cost and selling price.
Business Break-Even Calculator
Calculate units and revenue needed to cover fixed and variable costs.
Profit Margin Calculator
Calculate net profit and margin from revenue and expenses.
Working Capital Calculator
Calculate working capital and current ratio from short-term assets and liabilities.
Burn Rate & Runway Calculator
Calculate monthly net cash burn and the estimated months of operating runway remaining.
ROAS Calculator
Calculate return on ad spend and contribution after media cost.
Business Loan Payment Calculator
Estimate a fixed-rate business loan payment and total interest.
Quick Ratio Calculator
Compare quick assets with current liabilities.
Cash Ratio Calculator
Compare cash resources with current liabilities.
Cash Conversion Cycle Calculator
Combine inventory, receivable and payable days into a cash operating cycle.
Days Sales Outstanding Calculator
Estimate receivable days from annual credit sales and average receivables.
Inventory Turnover Calculator
Calculate inventory turns and average days held.
Contribution Margin Calculator
Calculate contribution margin and operating profit after fixed costs.
Operating Leverage Calculator
Estimate operating-income sensitivity to a sales change.
EBITDA Multiple Valuation Calculator
Estimate enterprise and equity value from EBITDA and a selected multiple.
SDE Business Valuation Calculator
Estimate small-business value from seller’s discretionary earnings and a multiple.
Discounted Cash Flow Calculator
Estimate enterprise value from growing cash flow and a terminal value.
Ecommerce Profit Calculator
Estimate profit after product, fulfillment, platform and advertising costs.
Employee Cost Calculator
Estimate first-year and monthly loaded employee cost.
Payment Processing Fee Calculator
Estimate percentage and fixed processing fees and net transaction proceeds.
Invoice Late Fee Calculator
Estimate a late fee and total amount due from an entered monthly and fixed charge.
Current Ratio Calculator
Calculate current ratio, working capital and liability coverage.
EBITDA Margin Calculator
Calculate EBITDA margin and an implied enterprise value at an entered multiple.
Gross Profit Calculator
Calculate gross profit, gross margin and cost of goods sold.
Return on Assets Calculator
Calculate profit as a percentage of average assets.
Return on Equity Calculator
Calculate profit as a percentage of average equity.
Return on Invested Capital Calculator
Calculate operating profit as a percentage of invested capital.
Accounts Receivable Aging Calculator
Calculate weighted receivable age and the over-60-day balance share.
Accounts Payable Turnover Calculator
Calculate payables turnover and days payable outstanding.
Days Payable Outstanding Calculator
Calculate average supplier-payment days from purchases and payables.
Working Capital Requirement Calculator
Estimate cash tied in the operating cycle after available credit.
Business DSCR Calculator
Calculate business debt-service coverage, cushion and debt capacity at a target ratio.
Equipment Lease vs. Buy Calculator
Compare lease cost with financed purchase cost after residual value.
Contractor vs. Employee Cost Calculator
Compare contractor fees with salary, benefits, payroll burden and employee overhead.
Economic Order Quantity Calculator
Calculate EOQ, annual order count and modeled ordering-plus-holding cost.
Inventory Reorder Point Calculator
Calculate lead-time demand, safety stock and an inventory reorder point.
Inventory Carrying Cost Calculator
Estimate annual and monthly capital, storage and inventory-risk costs.
Target Margin Pricing Calculator
Calculate required selling price, contribution and break-even units.
Pallet / Box Loading Calculator
Estimate boxes per pallet and volume utilization from pallet and box dimensions.
Straight-Line Depreciation Calculator
Calculate yearly and monthly straight-line depreciation from cost, salvage value and useful life.
Double Declining Balance Depreciation Calculator
Calculate depreciation, book value and accumulated depreciation for any year under the double-declining-balance method.
GDP Calculator
Calculate gross domestic product from consumption, investment, government spending, exports and imports.
Debt-to-Equity and Debt Ratio Calculator
Calculate debt-to-equity, the debt ratio and the equity multiplier from assets and liabilities.
Interest Coverage Ratio Calculator
Calculate how many times operating income covers interest expense.
Asset Turnover Calculator
Calculate revenue earned per dollar of average assets.
Operating Margin Calculator
Calculate operating margin, operating income and gross margin from revenue, costs and expenses.
Cost of Goods Sold (COGS) Calculator
Calculate cost of goods sold from beginning inventory, purchases and ending inventory.
DuPont Analysis Calculator
Break return on equity into profit margin, asset turnover and the equity multiplier.
Employee Turnover Rate Calculator
Calculate the turnover rate from separations and the average headcount.
Net Promoter Score Calculator
Calculate the net promoter score from counts of promoters, passives and detractors.
Marketing Metrics Calculator
Calculate click-through rate, cost per click, cost per thousand impressions and cost per conversion.
Profit Goal Calculator
Calculate the units and revenue needed to reach a profit goal from fixed costs, price and variable cost.
Sum-of-the-Years'-Digits Depreciation Calculator
Calculate depreciation, book value and accumulated depreciation for any year under the sum-of-the-years'-digits method.
Units of Production Depreciation Calculator
Calculate depreciation from how much an asset is used, rather than how many years have passed.
OEE (Overall Equipment Effectiveness) Calculator
Calculate overall equipment effectiveness from availability, performance and quality.
Takt Time Calculator
Calculate takt time from available production time and customer demand.
Safety Stock Calculator
Calculate safety stock and the reorder point from service level, demand variation and lead time.
Little's Law Calculator
Calculate the average number of items in a system from the arrival rate and the time each spends there.
Conversion Rate Calculator
Calculate conversion rate, revenue per visitor and revenue per conversion.
A/B Test Significance Calculator
Test whether the gap between two conversion rates is likely to be real, with the z-score and p-value.
Overhead Rate Calculator
Calculate the overhead rate on labor cost and the overhead per labor hour.
Education & Student Loans
Model student debt, college savings and education economics.
Student Loan Payment Calculator
Calculate payment and interest for a fixed-rate student loan.
Student Loan Payoff Calculator
Estimate student-loan payoff time and remaining interest at a chosen monthly payment.
Student Loan Refinance Calculator
Estimate break-even and savings from a lower refinance rate.
529 Plan Growth Calculator
Project college savings from a balance and monthly deposits.
College Savings Goal Calculator
Calculate monthly savings needed for a future education target.
Student Loan Interest Capitalization Calculator
Estimate accrued interest and balance after capitalization.
Education ROI Calculator
Estimate simple ROI and payback from education cost and earnings increase.
GPA Calculator
Calculate unweighted and weighted GPA from a list of course grades and credit hours.
Grade Target Calculator
Calculate the score needed on remaining coursework to reach a target final grade.
College Cost Calculator
Project a multi-year college cost after education inflation.
Student Budget Calculator
Set a target for one budget category from monthly resources.
529 State Tax Benefit Calculator
Estimate a state deduction or credit benefit from a 529 contribution.
Income-Driven Repayment Calculator
Estimate a monthly federal student-loan payment from discretionary income assumptions.
Parent PLUS Loan Calculator
Estimate payment, total interest and origination fee on Parent PLUS borrowing.
PSLF Calculator
Project balance, payment count and out-of-pocket payments to a forgiveness point.
Scholarship Impact Calculator
Calculate annual net cost, gift aid and remaining borrowing need.
Student Loan Consolidation Rate Calculator
Calculate a weighted rate and total balance across three student loans.
Test Score Percentage Calculator
Calculate a test score as a percentage and how many correct answers a target score needs.
Everyday Money
Handle percentages, discounts, pay conversions and inflation.
Percentage Calculator
Calculate what percentage one number represents of another.
Percentage Change Calculator
Calculate absolute and percentage change between two values.
Discount Calculator
Calculate sale price, tax and savings from a percentage discount.
Tip Calculator
Calculate a tip, the final bill and an even per-person split for a group.
Salary to Hourly Calculator
Convert annual salary into hourly and monthly gross pay.
Pay Raise Calculator
Calculate new annual pay and monthly increase from a raise.
Inflation Calculator
Project the future nominal cost and purchasing-power loss of today’s spending.
Real Wage Calculator
Calculate a pay change after inflation.
VAT Calculator
Estimate a VAT amount and tax-inclusive price using an entered local rate.
Prorated Rent Calculator
Calculate rent for a partial month from the monthly rent, the days in the month and the days occupied.
Unit Price Comparison Calculator
Compare the unit price of two package sizes and see how much the cheaper one saves.
TV Size Calculator
Calculate a screen's width, height and area from its diagonal size and aspect ratio.
Bonds & Fixed Income
Price bonds, compare yields and measure interest-rate sensitivity.
Bond Price Calculator
Price a plain fixed-rate bond from coupon, yield and maturity.
Yield to Maturity Calculator
Estimate the yield that discounts a bond’s cash flows to market price.
Bond Current Yield Calculator
Compare annual coupon income with a bond’s market price.
Bond Duration Calculator
Estimate modified duration and DV01 for a plain fixed-rate bond.
DV01 Calculator
Estimate dollar price sensitivity to a one-basis-point yield move.
Treasury Bill Calculator
Calculate investment yield and bank-discount yield for a T-bill.
Bond Ladder Calculator
Divide an investment across ladder rungs and estimate annual interest.
Muni vs. Taxable Bond Calculator
Compare a taxable after-tax yield with a municipal tax-equivalent yield.
Real Yield Calculator
Estimate return after an inflation assumption.
Yield to Call Calculator
Estimate yield to call from bond price, coupons, call price and call date.
Bond Convexity Calculator
Estimate bond convexity, price and a duration-plus-convexity yield-shock approximation.
Zero-Coupon Bond Calculator
Calculate the purchase price and accretion of a zero-coupon bond.
Callable Bond Calculator
Estimate yield to the first call date and the call premium or discount.
Bond Portfolio Duration Calculator
Calculate weighted modified duration and DV01 for a three-bond portfolio.
Bond Coupon Reinvestment Calculator
Project coupon income and reinvestment growth through maturity.
TIPS Inflation Adjustment Calculator
Estimate inflation-adjusted TIPS principal and final-year coupon.
Freelance & Self-Employed
Price independent work, plan taxes and replace employee benefits.
W-2 vs. 1099 Calculator
Compare employee compensation with contractor revenue after expenses and extra tax.
Freelance Hourly Rate Calculator
Calculate an hourly rate that covers compensation, benefits, overhead and taxes.
Contractor Rate Calculator
Translate a salary target into a sustainable contractor rate.
Billable Hours Calculator
Calculate billable hours and utilization required for a revenue target.
Project Profitability Calculator
Estimate project profit and margin after labor and direct expenses.
Quarterly Estimated Tax Calculator
Estimate the payment needed across remaining quarterly installments.
Estimated Tax Safe Harbor Calculator
Estimate additional prepayment needed to reach an entered prior-year safe harbor.
Home Office Deduction Calculator
Estimate deduction and tax savings from an eligible business-use share.
Business Mileage Deduction Calculator
Estimate a mileage deduction and possible tax savings.
Freelancer Benefits Gap Calculator
Estimate the revenue needed to replace salary, benefits and overhead.
Commission Calculator
Calculate commission and total compensation from sales, rate and base pay.
Payment Gross-Up Calculator
Calculate the gross payment needed to deliver a desired net amount.
Solo 401(k) Contribution Calculator
Estimate maximum solo 401(k) contribution capacity from self-employment profit and age.
Startup & SaaS
Model recurring revenue, retention, acquisition economics and ownership dilution.
MRR & ARR Calculator
Calculate ending monthly recurring revenue and annual recurring revenue.
Net Revenue Retention Calculator
Calculate NRR and GRR from expansion, contraction and churn.
LTV:CAC Calculator
Estimate customer lifetime value and the LTV-to-CAC ratio.
CAC Payback Calculator
Estimate how many months of customer gross profit recover acquisition cost.
SaaS Churn Calculator
Calculate monthly customer churn and a simple implied customer lifetime.
Pre-Money & Post-Money Valuation Calculator
Calculate investor and existing-holder ownership after a priced round.
Startup Dilution Calculator
Estimate ownership dilution from a new investment round.
SAFE Conversion Calculator
Estimate conversion valuation and ownership from a SAFE cap or discount.
Convertible Note Calculator
Estimate accrued note value and conversion ownership under a cap or discount.
MRR Growth Calculator
Calculate ending MRR, net new MRR and net growth rate.
Gross Revenue Retention Calculator
Calculate recurring-revenue retention before expansion.
SaaS Rule of 40 Calculator
Add annual recurring-revenue growth and profitability margin.
SaaS Magic Number Calculator
Compare annualized net new recurring revenue with prior-quarter sales and marketing spend.
Option Pool Dilution Calculator
Calculate new pool shares and existing-holder dilution at a target pool percentage.
Household & Life
Plan insurance, healthcare, childcare, budgets and major life transitions.
Stay-at-Home vs. Childcare Calculator
Estimate the annual cash-flow advantage of working after childcare and job costs.
Life Insurance Needs Calculator
Estimate additional life insurance need after assets and existing coverage.
HSA Tax Savings Calculator
Estimate tax savings and net cost of an HSA contribution.
FSA Tax Savings Calculator
Estimate tax savings and net cost of an FSA election.
Health Insurance Plan Cost Calculator
Estimate expected and worst-case annual health-plan cost.
Emergency Fund Depletion Calculator
Estimate how long a reserve lasts with monthly inflows, outflows and yield.
Sinking Fund Calculator
Calculate the monthly deposit needed for a known future expense.
Net Worth Calculator
Calculate total household assets less mortgage and other liabilities.
50/30/20 Budget Calculator
Calculate a target amount for a selected budget category.
Subscription Cost Calculator
Calculate annual subscription spending and its long-term opportunity cost.
Cost of Living Calculator
Estimate the salary needed to preserve purchasing power across two cost indexes.
Moving Cost Calculator
Estimate cash needed for transport, deposits, overlap and setup after reimbursements.
Job Offer Total Compensation Calculator
Estimate annual offer value from salary, bonus, equity, benefits and job costs.
Severance Runway Calculator
Estimate months of essential spending covered by net severance and reserves.
Paid Leave Income Gap Calculator
Estimate lost take-home pay, leave benefits and the remaining funding gap.
Maternity Leave Calculator
Estimate the household funding gap during maternity or parental leave.
Childcare Break-Even Salary Calculator
Calculate the gross salary required to cover childcare and work-related costs.
Disability Insurance Needs Calculator
Estimate the monthly income-replacement gap after employer and other benefits.
Wedding Budget Calculator
Build a wedding budget with contingency and calculate monthly savings required.
Income-Based Shared Expense Calculator
Split a shared monthly expense in proportion to two incomes.
Roommate Rent Split Calculator
Split rent using private-room size and an equal common-space allocation.
Savings Rate Calculator
Calculate savings rate, monthly savings and remaining spending.
Salary Negotiation Calculator
Calculate first-year compensation change across salary, bonus, equity and benefits.
Unemployment Runway Calculator
Estimate how long cash reserves last after unemployment income and other inflows.
Body Composition
Estimate BMI, body fat, lean mass and other body-composition measures.
BMI Calculator
Calculate body mass index from height and weight.
Body Fat Percentage Calculator
Estimate body fat percentage and lean mass using the U.S. Navy circumference method.
Ideal Weight Calculator
Estimate a reference body weight from height using the Devine formula.
Lean Body Mass Calculator
Estimate lean body mass and fat mass using the Boer formula.
Waist-to-Hip Ratio Calculator
Calculate waist-to-hip and waist-to-height ratio from body measurements.
Body Surface Area Calculator
Calculate body surface area using the Mosteller and Du Bois formulas.
Pregnancy Weight Gain Calculator
Estimate recommended total and to-date pregnancy weight gain by pre-pregnancy BMI.
Due Date Calculator
Estimate a pregnancy due date and conception date from the first day of the last menstrual period.
Conception Date Calculator
Estimate a conception date and the equivalent last-menstrual-period date from a known or estimated due date.
Healthy Weight Range Calculator
Find the weight range that corresponds to a BMI of 18.5 to 24.9 at your height.
Weight to Reach a Target BMI Calculator
Find the weight that matches a target BMI at your height and how far you are from it.
Energy & Nutrition
Estimate calorie needs, macronutrient targets and energy expenditure.
BMR Calculator
Calculate basal metabolic rate using the Mifflin-St Jeor equation.
TDEE Calculator
Calculate total daily energy expenditure from BMR and activity level.
Calorie Goal Calculator
Calculate a target daily calorie intake and estimated weekly weight change.
Macronutrient Calculator
Calculate protein, carbohydrate and fat targets from a calorie goal and diet style.
Protein Intake Calculator
Calculate a daily protein target from body weight and training goal.
Calories Burned Calculator
Estimate calories burned from activity, duration and body weight using MET values.
Weight Loss Time Calculator
Estimate the weeks needed to reach a goal weight at a steady daily calorie deficit.
Carbohydrate Intake Calculator
Convert daily calories into a range of grams of carbohydrate using the Dietary Guidelines share of calories.
Fat Intake Calculator
Convert daily calories into a range of grams of fat, with a ceiling for saturated fat.
Fitness & Performance
Estimate training loads, heart-rate zones and pace.
One-Rep Max Calculator
Estimate a one-repetition maximum from a completed set using the Epley formula.
Target Heart Rate Calculator
Calculate a target training heart-rate zone using the Karvonen method.
Running Pace Calculator
Calculate pace per mile and speed from distance and time.
VO2 Max Calculator
Estimate VO2 max from the distance covered in a 12-minute run using the Cooper test formula.
Wilks Score Calculator
Calculate a Wilks score to compare powerlifting strength across different bodyweights.
Max Heart Rate Calculator
Estimate maximum heart rate by age with the Tanaka formula and the older 220 minus age rule.
Steps to Miles Calculator
Convert a step count into miles and kilometers from your stride length.
Clinical Estimates
Educational estimates for kidney function and blood alcohol concentration.
GFR Calculator
Estimate kidney function (eGFR) from creatinine, age and sex using the 2021 CKD-EPI equation.
BAC Calculator
Estimate blood alcohol concentration from drinks, body weight and elapsed time using the Widmark formula.
Creatinine Clearance Calculator
Estimate creatinine clearance from age, weight and serum creatinine using the Cockcroft-Gault equation.
Ovulation Calculator
Estimate the ovulation date, fertile window and next period from your last period and cycle length.
Pregnancy Week Calculator
Find how many weeks and days pregnant you are from the first day of your last period.
Cholesterol (LDL) Calculator
Estimate LDL, non-HDL cholesterol and the total-to-HDL ratio from a standard lipid panel.
Mean Arterial Pressure Calculator
Calculate mean arterial pressure and pulse pressure from a blood pressure reading.
IVF Due Date Calculator
Estimate a due date from an embryo transfer date and the age of the embryo at transfer.
Period Calculator
Predict the next three period start dates from the last period and your cycle length.
Algebra & Arithmetic
Solve equations, simplify fractions and ratios, and work with exponents, roots and logs.
Quadratic Formula Calculator
Solve ax² + bx + c = 0 for both roots.
Fraction Simplifier Calculator
Reduce a fraction to lowest terms using the greatest common factor.
Exponent Calculator
Calculate base raised to an exponent, including negative and fractional exponents.
Root Calculator
Calculate the nth root of any value, including cube and higher roots.
Logarithm Calculator
Calculate the logarithm of a value in any base.
Ratio Simplifier Calculator
Reduce a ratio to its lowest whole-number terms.
Rounding Calculator
Round a value to a chosen number of decimal places.
Weighted Average Calculator
Calculate an average where each value counts by a different weight.
2x2 Matrix Determinant Calculator
Calculate the determinant and trace of a 2x2 matrix.
3x3 Matrix Determinant Calculator
Calculate the determinant and trace of a 3x3 matrix using cofactor expansion.
Scientific Calculator
A full scientific keypad for trig, log, exponent, root, factorial and memory calculations.
Fraction Calculator
Add, subtract, multiply or divide two fractions and get the answer in lowest terms plus its decimal value.
Decimal to Fraction Calculator
Turn a decimal into the closest fraction under a denominator limit you choose.
Arithmetic Sequence Calculator
Find the last term and the sum of an arithmetic sequence from its first term, common difference and length.
Geometric Sequence Calculator
Find the last term and the sum of a geometric sequence from its first term, common ratio and length.
Percent Difference Calculator
Calculate the percent difference between two values, measured against their average.
Proportion Calculator
Solve a proportion a ÷ b = c ÷ x for the unknown value.
Roman Numeral Calculator
Convert a whole number from 1 to 3,999 into a Roman numeral.
Completing the Square Calculator
Rewrite a quadratic in vertex form and find the vertex from its three coefficients.
Dot Product Calculator
Calculate the dot product, the angle and the cross product magnitude of two 3D vectors.
Mixed Number to Improper Fraction Calculator
Convert a mixed number into an improper fraction and a decimal.
Exponential Growth Calculator
Calculate the ending value, the doubling time and the total growth for a steady percentage change per period.
Geometry
Calculate area, volume, surface area and distance for common shapes.
Rectangle Area & Perimeter Calculator
Calculate the area and perimeter of a rectangle.
Circle Area & Circumference Calculator
Calculate the area and circumference of a circle from its radius.
Triangle Area (Heron's Formula) Calculator
Calculate a triangle's area and perimeter from its three side lengths.
Pythagorean Theorem Calculator
Calculate the hypotenuse of a right triangle from its two legs.
Sphere Volume & Surface Area Calculator
Calculate the volume and surface area of a sphere from its radius.
Cylinder Volume & Surface Area Calculator
Calculate the volume and surface area of a cylinder.
Cone Volume & Surface Area Calculator
Calculate the volume and total surface area of a cone.
Distance & Slope Calculator
Calculate the distance and slope between two points on a plane.
Trapezoid Area Calculator
Calculate the area and midsegment of a trapezoid from its two parallel bases and its height.
Parallelogram Area Calculator
Calculate the area and perimeter of a parallelogram from its base, height and slanted side.
Rectangular Prism Volume Calculator
Calculate the volume, surface area and space diagonal of a box from its length, width and height.
Triangle Third Side Calculator
Find the third side, area and perimeter of a triangle from two sides and the angle between them.
Arc Length and Sector Area Calculator
Calculate arc length, sector area and chord length from a circle's radius and central angle.
Ellipse Area Calculator
Calculate the area and approximate perimeter of an ellipse from its two semi-axes.
Pyramid Volume Calculator
Calculate the volume and surface area of a rectangular pyramid from its base and height.
Right Triangle Calculator
Calculate the hypotenuse, both acute angles and the area of a right triangle from its two legs.
Aquarium Volume Calculator
Calculate an aquarium's volume in gallons and liters, and the weight of the water it holds.
Annulus Area Calculator
Calculate the area, width and edge length of a ring from its outer and inner radius.
Regular Polygon Calculator
Calculate the area, perimeter, apothem and interior angle of a regular polygon from its sides and side length.
Rhombus Area Calculator
Calculate the area, side and perimeter of a rhombus from its two diagonals.
Hemisphere Volume Calculator
Calculate the volume, curved surface and total surface of a hemisphere from its radius.
Cone Frustum Calculator
Calculate the volume, slant height and surface area of a truncated cone from its two radii and height.
Capsule Volume Calculator
Calculate the volume and surface area of a capsule from its radius and straight length.
Triangular Prism Volume Calculator
Calculate the volume of a triangular prism from the triangle's base and height and the prism's length.
Law of Sines Calculator
Find the two unknown sides and the third angle of a triangle from two angles and one side.
Cube Calculator
Calculate the volume, surface area, face diagonal and space diagonal of a cube from its side.
Equilateral Triangle Calculator
Calculate the area, height, perimeter and inscribed circle radius of an equilateral triangle from its side.
Trigonometry Calculator
Calculate the sine, cosine and tangent of an angle in degrees.
Golden Ratio Calculator
Split a length into the golden ratio from the longer part, the shorter part or the whole.
Midpoint Calculator
Find the midpoint and the distance between two points on a plane.
Statistics & Probability
Calculate averages, spread, combinations, probability and confidence intervals.
Mean & Median Calculator
Calculate the mean and median of six values.
Standard Deviation Calculator
Calculate population and sample standard deviation for six values.
Range & Midrange Calculator
Calculate the range and midrange of six values.
Permutation & Combination Calculator
Calculate permutations and combinations for choosing r items from n.
Simple Probability Calculator
Calculate the probability and odds of a simple event.
Z-Score Calculator
Calculate a z-score and its approximate percentile under a normal distribution.
Confidence Interval Calculator
Calculate a confidence interval around a sample mean.
Sample Size Calculator
Calculate the sample size needed for a target margin of error and confidence level.
Binomial Probability Calculator
Calculate the chance of exactly k successes, and of k or fewer, in n independent trials.
Normal Distribution Probability Calculator
Calculate the probability that a normally distributed value falls between two limits.
P-Value from Z-Score Calculator
Calculate the p-value for a z-score in a left-tailed, right-tailed or two-tailed test.
Expected Value Calculator
Calculate the expected value of a bet or decision from its chance of winning, the amount won and the amount lost.
Bayes' Theorem Calculator
Calculate the chance of a condition after a positive or a negative test from prevalence, sensitivity and false positive rate.
Number Theory & Precision
Calculate factors, multiples, scientific notation and measurement error.
GCF & LCM Calculator
Calculate the greatest common factor and least common multiple of two numbers.
Prime Factorization Calculator
Calculate the number of distinct prime factors and the largest prime factor of a value.
Scientific Notation Calculator
Convert a value into mantissa-and-exponent scientific notation.
Percent Error Calculator
Calculate the percent error between an experimental and a theoretical value.
Number Base Converter Calculator
Convert a decimal number into binary, hexadecimal and octal at the same time.
Factorial Calculator
Calculate n factorial for a whole number up to 170 and count its trailing zeros.
Modulo Calculator
Find the remainder and whole-number quotient when one number is divided by another.
Fibonacci Calculator
Find the nth Fibonacci number, the ratio to the term before it and the sum of the first n terms.
Prime Number Calculator
Find the smallest prime factor of a number, and the nearest primes above and below it.
Date & Time
Calculate age, date differences, day of the week and countdowns.
Age Calculator
Calculate exact age in years and total days lived from a birth date.
Date Difference Calculator
Calculate the number of days and weeks between two dates.
Day of the Week Calculator
Find what day of the week any date falls on, and its day of the year.
Day Counter Calculator
Count down the days and weeks until a target date.
Add Days to a Date Calculator
Add or subtract days and weeks from any date and see the resulting date and weekday.
Business Days Calculator
Count the weekdays between two dates, plus the calendar days and weekend days.
Unit Conversion
Convert length, weight, temperature, volume, speed and tire sizes.
Length Converter Calculator
Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards and miles.
Weight Converter Calculator
Convert between grams, kilograms, pounds, ounces, stone and metric tons.
Volume Converter Calculator
Convert between milliliters, liters, US gallons, quarts, cups and fluid ounces.
Speed Converter Calculator
Convert between meters per second, km/h, mph and knots.
Temperature Converter Calculator
Convert between Celsius, Fahrenheit and Kelvin.
Tire Size Comparison Calculator
Compare overall diameter between two tire sizes and estimate speedometer error.
Currency Converter Calculator
Convert an amount between currencies using a live, dated exchange rate.
Area Converter Calculator
Convert between square inches, square feet, square yards, square meters, acres, hectares, square kilometers and square miles.
Time Converter Calculator
Convert between seconds, minutes, hours, days, weeks and years.
Energy Converter Calculator
Convert between joules, kilojoules, kilocalories, watt-hours, kilowatt-hours, BTU and foot-pounds.
Pressure Converter Calculator
Convert between pascals, kilopascals, bar, PSI, atmospheres, mmHg and inches of mercury.
Power Converter Calculator
Convert between watts, kilowatts, mechanical horsepower, metric horsepower and BTU per hour.
Height Converter Calculator
Convert a height between feet and inches and centimeters in either direction.
Angle Converter Calculator
Convert between degrees, radians, gradians, arcminutes, arcseconds and turns.
Data Rate Converter Calculator
Convert between bits and bytes per second, from bps to gigabytes per second.
Force Converter Calculator
Convert between newtons, kilonewtons, pounds-force, kilograms-force, ounces-force and dynes.
Torque Converter Calculator
Convert between newton-meters, pound-feet, pound-inches and kilogram-force meters.
Frequency Converter Calculator
Convert between hertz, kilohertz, megahertz, gigahertz and revolutions per minute.
Fuel Economy Converter Calculator
Convert between US miles per gallon, imperial miles per gallon, liters per 100 km and kilometers per liter.
Home & Construction
Estimate material, tile, roofing and square footage for a project.
Concrete, Gravel & Mulch Calculator
Estimate the volume and bag count needed for concrete, gravel, mulch or topsoil.
Tile Flooring Calculator
Estimate the number of tiles needed for a room, including a waste allowance.
Roofing Calculator
Estimate roofing squares needed from footprint and roof pitch.
Square Footage Calculator
Calculate area in square feet and square yards from length and width.
Cut-List / Sheet Nesting Calculator
Estimate the number of full sheets needed to cut a set of pieces, including a waste allowance.
Fastener Pilot & Clearance Hole Reference Calculator
Look up the recommended pilot and clearance hole size for a wood screw gauge and wood type.
Pool Volume Calculator
Calculate a pool's volume in gallons, cubic feet and liters from its size and average depth.
Paint Calculator
Estimate the gallons of paint a room needs from its size, doors, windows and coats.
Fence Calculator
Estimate the posts, pickets and rails a fence needs from its length and layout.
Drywall Calculator
Estimate how many drywall sheets a room needs from its area, sheet size and waste allowance.
Paver Calculator
Estimate how many pavers cover an area from the paver size and a waste allowance.
Wallpaper Calculator
Estimate the rolls of wallpaper a room needs from its size, openings and waste.
Carpet Calculator
Estimate square yards and roll length of carpet needed for a room.
Rainwater Harvesting Calculator
Estimate the gallons of rainwater a roof can collect from its area and the rainfall.
Cubic Yard Calculator
Calculate cubic yards, cubic feet and cubic meters from a length, a width and a depth in feet.
Cubic Feet Calculator
Calculate cubic feet, liters and gallons from a length, a width and a height in any common unit.
Flooring Calculator
Calculate the boxes of flooring needed to cover a room from its size, the box coverage and a waste allowance.
Science & Electronics
Calculate circuits, density, molarity and voltage drop.
Ohm's Law Calculator
Calculate voltage and power from current and resistance.
Density Calculator
Calculate density and specific gravity from mass and volume.
Molarity Calculator
Calculate the molar concentration of a solution from moles and volume.
Voltage Drop Calculator
Estimate voltage drop and power loss over a wire run.
Dilution Calculator
Calculate the stock volume and diluent needed to reach a target concentration.
pH Value Calculator
Calculate pH and pOH from a hydrogen ion concentration.
Half-Life Calculator
Calculate the amount remaining, the share remaining and the decay constant after a given time.
Series and Parallel Resistor Calculator
Calculate the combined resistance of up to three resistors in series and in parallel.
LED Resistor Calculator
Calculate the current-limiting resistor for an LED and the next standard E12 value.
Watts to Amps Calculator
Convert watts to amps for a given voltage, power factor and single-phase or three-phase supply.
Resistor Color Code Calculator
Read a four-band resistor's value and tolerance range from its color bands.
Voltage Divider Calculator
Calculate the output voltage and current of a two-resistor voltage divider.
RC Time Constant Calculator
Calculate the time constant, cutoff frequency and settling time of a resistor-capacitor circuit.
Combined Gas Law Calculator
Find the final volume of a gas after its pressure and temperature change.
Percent Yield Calculator
Calculate the percent yield of a reaction from the actual and theoretical yield.
PPM Concentration Calculator
Convert a mass of solute in a volume of water to parts per million and parts per billion.
Weather
Calculate wind chill, heat index and dew point using the official National Weather Service formulas.
Wind Chill Calculator
Calculate the wind chill "feels-like" temperature using the official NWS formula.
Heat Index Calculator
Calculate the heat index "feels-like" temperature from air temperature and humidity.
Dew Point Calculator
Calculate dew point and the temperature-dew point spread from temperature and humidity.
Heating & Cooling Degree Days Calculator
Calculate heating and cooling degree days from an average daily temperature using the standard 65°F base.
Snow-to-Liquid Ratio Calculator
Estimate snowfall from liquid precipitation using an entered snow-to-liquid ratio.
Plumbing
Size pipe, flow, drainage and water heating for common residential plumbing tasks.
Pipe Volume Calculator
Calculate the volume of water held in a pipe run from its diameter and length.
Flow Rate (GPM) Calculator
Calculate gallons per minute from pipe diameter and flow velocity.
Drain Slope Calculator
Calculate the drop needed along a drain run at a chosen slope.
Drainage Fixture Unit (DFU) Calculator
Total the drainage fixture units for a group of fixtures and estimate the minimum drain size.
Water Heater Sizing Calculator
Estimate a storage tank size from household size, or a required flow rate for a tankless unit.
Pipe Friction & Pressure Loss Calculator
Estimate pressure loss along a pipe run using the Hazen-Williams equation.
HVAC
Estimate duct sizing, airflow, equipment tonnage and static pressure for heating and cooling systems.
Duct Sizing Calculator
Estimate the round duct diameter needed for an airflow at a target friction rate.
CFM / Air Changes Per Hour Calculator
Calculate required airflow from room volume and a target air-change rate.
HVAC BTU/Tonnage Rough Sizing Calculator
Estimate a rough cooling load and equipment tonnage from square footage and climate zone.
Static Pressure Calculator
Add supply-side and return-side readings to find total external static pressure.
SEER Upgrade Savings Calculator
Estimate annual operating-cost savings from upgrading to a higher-SEER system.
Electrical Trade
Size conduit, wire, transformers and boxes using standard NEC reference calculations.
Conduit Fill Calculator
Calculate conduit fill percentage from conductor and conduit areas.
Wire Ampacity Sizing Calculator
Look up a conductor's base ampacity and apply a derating factor.
Transformer Sizing Calculator
Calculate primary and secondary full-load current from a transformer's KVA rating.
Three-Phase Power Calculator
Calculate real and apparent power from three-phase voltage, current and power factor.
Electrical Box Fill Calculator
Calculate required box volume from conductors, devices, grounds and clamps.
Concrete & Masonry
Estimate concrete, rebar, block and footing quantities for common construction projects.
Concrete Volume & Bag Calculator
Calculate concrete volume and the number of bagged-mix bags needed for a slab or footing.
Rebar Calculator
Calculate total rebar length and weight for a rectangular reinforcing grid.
Concrete Block (CMU) Calculator
Estimate the number of standard 8x16 blocks and mortar bags for a wall.
Mortar Mix Calculator
Calculate mortar volume and bags needed for a given number of brick or block units.
Footing Size Calculator
Estimate the minimum footing width from load and allowable soil bearing pressure.
Carpentry
Calculate rafter, stair, framing and decking dimensions for common carpentry projects.
Rafter Length Calculator
Calculate common rafter length and roof angle from run and pitch.
Stair Stringer Calculator
Calculate the number of risers and stringer length from total rise, target riser and tread.
Roof Pitch & Angle Calculator
Convert a roof pitch (rise per 12) into a slope angle and percent grade.
Board Feet Calculator
Calculate board feet per board and for a full order from dimensional lumber sizes.
Joist Span Reference Calculator
Estimate a rough maximum joist span from nominal depth, spacing and a grade adjustment.
Deck Material Calculator
Estimate decking boards and joist count from deck dimensions and board spacing.
Machining
Calculate feeds, speeds, tap drill sizes and thread engagement for machine shop work.
Feeds and Speeds Calculator
Calculate spindle speed and feed rate from surface speed, tool diameter, chip load and flute count.
Tap Drill Size Calculator
Calculate the tap drill diameter for a target percent of thread engagement.
Thread Engagement Calculator
Calculate percent thread engagement from major diameter, TPI and the actual drilled hole size.
Surface Speed Calculator
Calculate surface speed (SFM) from workpiece diameter and spindle RPM.
Craft & Sewing
Estimate yarn, fabric, binding and pattern-scaling quantities for knitting, crochet and sewing projects.
Yarn Requirement Calculator
Estimate total yardage and skeins needed for a knit or crochet project from its dimensions and gauge.
Knitting & Crochet Gauge Calculator
Convert a pattern's stitch count for your own gauge and a target finished width.
Fabric Yardage Calculator
Estimate fabric yardage needed for a garment from pattern pieces, fabric width and a waste allowance.
Quilt Backing & Binding Calculator
Estimate backing and binding fabric yardage from quilt dimensions.
Pattern Scaling Calculator
Calculate a photocopier scale percentage and a resized pattern-piece dimension.
Seam Allowance Calculator
Calculate the cut size of a patch from its finished size and seam allowance, and total fabric needed.
Networking & Technology
Calculate IP subnets, password entropy, file transfer time and digital storage conversions.
Subnet Calculator
Calculate the network address, broadcast address and usable host count for an IPv4 address and CIDR prefix.
Password Entropy Calculator
Estimate a password's entropy in bits and the average time to crack it at a chosen attack speed.
Download Time Calculator
Estimate transfer time from a file size and connection speed, in either decimal or binary units.
Storage Converter Calculator
Convert between bits, bytes, kilobytes, kibibytes, megabytes, mebibytes and their gigabyte and terabyte equivalents.
Aspect Ratio Calculator
Reduce a width and height to their aspect ratio and find the height at a new width.
PPI (Pixels Per Inch) Calculator
Calculate a screen's pixel density and pixel pitch from its resolution and diagonal size.
Bandwidth and Data Usage Calculator
Estimate monthly data use from a bitrate and the hours you stream or transfer each day.
Physics & Mechanics
Work out speed, force, energy, motion, waves and gas behavior from the standard physics formulas.
Horsepower Calculator
Calculate horsepower and kilowatts from torque and engine speed.
Speed, Distance and Time Calculator
Calculate average speed from distance and travel time.
Kinetic Energy Calculator
Calculate kinetic energy and momentum from mass and speed.
Newton's Second Law Force Calculator
Calculate force in newtons and pounds-force from mass and acceleration.
Uniform Acceleration Calculator
Calculate final speed, distance and average speed under constant acceleration.
Hooke's Law Calculator
Calculate a spring's force and stored energy from its spring constant and stretch.
Ideal Gas Law Calculator
Calculate the pressure of a gas from its amount, temperature and volume.
Gravitational Potential Energy Calculator
Calculate the potential energy of a mass raised to a height.
Work and Power Calculator
Calculate the work done by a force over a distance, and the power if you know the time.
Wavelength and Frequency Calculator
Convert the frequency of a radio or light wave into its wavelength and period.
Projectile Motion Calculator
Calculate the range, maximum height and flight time of a projectile from its launch speed and angle.
Free Fall Calculator
Calculate the fall time and impact speed of an object dropped from a height.
Centripetal Force Calculator
Calculate the inward force and acceleration needed to move a mass around a curve.
Pendulum Period Calculator
Calculate the period and frequency of a pendulum from its length.
Time & Clock
Work out sleep times, hours worked, time differences, time zones and military time.
Sleep Calculator
Find bedtimes that let you wake at the end of a sleep cycle, from your wake-up time.
Time Card Calculator
Calculate hours worked and pay for a shift from start time, end time and unpaid break.
Time Duration Calculator
Calculate the hours and minutes between two times of day, including across midnight.
Add Time Calculator
Add hours and minutes to a time of day and see the resulting time and how many days later it falls.
Time Zone Calculator
Convert a time between two time zones, with a setting for daylight saving in each.
Military Time Converter Calculator
Convert a time between 12-hour AM and PM and 24-hour military time.
Hours and Minutes to Decimal Calculator
Convert hours and minutes into decimal hours for a timesheet or an invoice.
Decimal Hours to Time Calculator
Convert decimal hours into hours and minutes.
Cooking & Kitchen
Scale recipes, compare pan sizes, dial in a coffee ratio and price a serving.
Recipe Scaling Calculator
Scale an ingredient amount from the servings in a recipe to the servings you want.
Baking Pan Size Calculator
Compare two pan sizes and find the multiplier that keeps the batter depth the same.
Coffee to Water Ratio Calculator
Calculate grams of ground coffee from the water you are brewing and your chosen ratio.
Recipe Cost Per Serving Calculator
Calculate the cost of one serving from total ingredient cost, servings and an overhead allowance.
Energy & Utilities
Price appliance electricity, EV charging and fuel economy, and size a battery for a load.
Electricity Cost Calculator
Calculate the kilowatt-hours and cost of running any appliance from its wattage, hours and your rate.
EV Charging Cost Calculator
Estimate monthly charging cost and cost per mile for an electric vehicle at home rates.
MPG Calculator
Calculate miles per gallon, fuel cost per mile and liters per 100 km from a fill-up.
Battery Runtime Calculator
Estimate how many hours a battery can run a load from its amp-hours, voltage and usable share.
Solar Panel Output Calculator
Estimate a solar array's daily and yearly energy from panels, wattage, sun hours and losses.
Solar Payback Calculator
Estimate the payback period and 25-year net savings of a solar system after incentives.
LED Bulb Savings Calculator
Calculate yearly electricity savings from swapping older bulbs for LEDs.
Generator Size Calculator
Estimate the generator wattage needed from running watts and the largest starting surge.
Lawn & Garden
Order mulch, topsoil, gravel, sand, seed and sod, and plan fertilizer and watering for a yard.
Mulch Calculator
Calculate the cubic yards and the bags of mulch needed to cover a bed at a chosen depth.
Topsoil Calculator
Calculate the cubic yards, bags and tons of topsoil needed for a lawn, a garden or a raised bed.
Gravel Calculator
Calculate the cubic yards and tons of gravel needed to cover a path, a driveway or a bed.
Sand Calculator
Calculate the cubic yards and tons of sand needed under pavers or in a play area.
Grass Seed Calculator
Calculate the pounds and bags of grass seed needed for a lawn from its area and a seeding rate.
Lawn Fertilizer Calculator
Calculate the pounds and bags of fertilizer needed to apply a set amount of nitrogen to a lawn.
Sod Calculator
Calculate the number of sod rolls needed to cover a lawn, with a waste allowance.
Lawn Watering Calculator
Calculate the gallons and sprinkler minutes needed to give a lawn a chosen depth of water.
Beyond a single formula
Interactive tools
Not every useful tool fits a single numeric formula. This one uses an interactive map instead.