Financial decisions, made visible
Free online calculators for money, health, math and home projects
Calculate the money. Understand the tradeoff.
582 free calculators for loans, mortgages, investing, retirement, taxes, business, health, math, conversions and home projects. Each result shows its formula, the assumptions behind it, its limits and the sources it follows.
Beyond money
Calculators for health, math, home projects and daily life
BMI Calculator
Calculate body mass index from height and weight.
↗02Age Calculator
Calculate exact age in years and total days lived from a birth date.
↗03Fraction Calculator
Add, subtract, multiply or divide two fractions and get the answer in lowest terms plus its decimal value.
↗04Percentage Calculator
Calculate what percentage one number represents of another.
↗05Paint Calculator
Estimate the gallons of paint a room needs from its size, doors, windows and coats.
↗06MPG Calculator
Calculate miles per gallon, fuel cost per mile and liters per 100 km from a fill-up.
↗07Time Card Calculator
Calculate hours worked and pay for a shift from start time, end time and unpaid break.
↗08Sleep Calculator
Find bedtimes that let you wake at the end of a sleep cycle, from your wake-up time.
↗09Electricity Cost Calculator
Calculate the kilowatt-hours and cost of running any appliance from its wattage, hours and your rate.
↗10Tip Calculator
Calculate a tip, the final bill and an even per-person split for a group.
↗11Length Converter Calculator
Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards and miles.
↗12Trapezoid Area Calculator
Calculate the area and midsegment of a trapezoid from its two parallel bases and its height.
↗Current benchmarks
Official mortgage and Treasury rates
Use dated Freddie Mac survey averages and U.S. Treasury yields as research benchmarks, then replace them with the actual lender quote or market price for your decision.
Open the current rate center →- 01Freddie Mac PMMSWeekly national mortgage survey benchmarks.
- 02U.S. TreasuryOfficial daily par-yield curve observations.
- 03Dated dataSource date and retrieval status stay visible.
Start with your decision
A complete calculator library
Estimate the outcome, reverse-plan the target, compare scenarios and move directly to the next useful calculation.
Loans & Payments
Compare payments, borrowing costs, terms and payoff strategies.
10 calculators↗02Mortgage & Home
Estimate affordability, monthly ownership cost, equity and refinance tradeoffs.
34 calculators↗03Investing & Returns
Model compounding, growth, income and investment returns.
45 calculators↗04Retirement
Translate future spending into portfolio, contribution and income targets.
38 calculators↗05Savings & Banking
Plan savings goals, reserves, yields, CDs and time to goal.
6 calculators↗06Debt & Credit
Understand payoff time, interest, utilization and consolidation.
9 calculators↗07Taxes & Paycheck
Create educational estimates for federal tax and take-home pay.
21 calculators↗08Auto Finance
Compare vehicle payments, leases, depreciation and running costs.
13 calculators↗09Real Estate Investing
Evaluate rental income, operating performance and leverage.
19 calculators↗10Business Finance
Calculate margins, break-even volume, liquidity and runway.
56 calculators↗11Education & Student Loans
Model student debt, college savings and education economics.
12 calculators↗12Everyday Money
Handle percentages, discounts, pay conversions and inflation.
12 calculators↗13Bonds & Fixed Income
Price bonds, compare yields and measure interest-rate sensitivity.
13 calculators↗14Freelance & Self-Employed
Price independent work, plan taxes and replace employee benefits.
11 calculators↗15Startup & SaaS
Model recurring revenue, retention, acquisition economics and ownership dilution.
13 calculators↗16Household & Life
Plan insurance, healthcare, childcare, budgets and major life transitions.
22 calculators↗17Body Composition
Estimate BMI, body fat, lean mass and other body-composition measures.
11 calculators↗18Energy & Nutrition
Estimate calorie needs, macronutrient targets and energy expenditure.
9 calculators↗19Fitness & Performance
Estimate training loads, heart-rate zones and pace.
7 calculators↗20Clinical Estimates
Educational estimates for kidney function and blood alcohol concentration.
9 calculators↗21Algebra & Arithmetic
Solve equations, simplify fractions and ratios, and work with exponents, roots and logs.
21 calculators↗22Geometry
Calculate area, volume, surface area and distance for common shapes.
29 calculators↗23Statistics & Probability
Calculate averages, spread, combinations, probability and confidence intervals.
13 calculators↗24Number Theory & Precision
Calculate factors, multiples, scientific notation and measurement error.
9 calculators↗25Date & Time
Calculate age, date differences, day of the week and countdowns.
5 calculators↗26Unit Conversion
Convert length, weight, temperature, volume, speed and tire sizes.
19 calculators↗27Home & Construction
Estimate material, tile, roofing and square footage for a project.
16 calculators↗28Science & Electronics
Calculate circuits, density, molarity and voltage drop.
16 calculators↗29Weather
Calculate wind chill, heat index and dew point using the official National Weather Service formulas.
5 calculators↗30Plumbing
Size pipe, flow, drainage and water heating for common residential plumbing tasks.
6 calculators↗31HVAC
Estimate duct sizing, airflow, equipment tonnage and static pressure for heating and cooling systems.
5 calculators↗32Electrical Trade
Size conduit, wire, transformers and boxes using standard NEC reference calculations.
5 calculators↗33Concrete & Masonry
Estimate concrete, rebar, block and footing quantities for common construction projects.
4 calculators↗34Carpentry
Calculate rafter, stair, framing and decking dimensions for common carpentry projects.
6 calculators↗35Machining
Calculate feeds, speeds, tap drill sizes and thread engagement for machine shop work.
4 calculators↗36Craft & Sewing
Estimate yarn, fabric, binding and pattern-scaling quantities for knitting, crochet and sewing projects.
6 calculators↗37Networking & Technology
Calculate IP subnets, password entropy, file transfer time and digital storage conversions.
7 calculators↗38Physics & Mechanics
Work out speed, force, energy, motion, waves and gas behavior from the standard physics formulas.
14 calculators↗39Time & Clock
Work out sleep times, hours worked, time differences, time zones and military time.
6 calculators↗40Cooking & Kitchen
Scale recipes, compare pan sizes, dial in a coffee ratio and price a serving.
4 calculators↗41Energy & Utilities
Price appliance electricity, EV charging and fuel economy, and size a battery for a load.
8 calculators↗42Lawn & Garden
Order mulch, topsoil, gravel, sand, seed and sod, and plan fertilizer and watering for a yard.
4 calculators↗Popular starting points
Answer the next money question
Loan Payment & Amortization Calculator
Calculate the monthly payment and total interest for a fixed-rate installment loan.
Mortgage Payment Calculator
Estimate principal, interest, property tax, insurance and HOA in one monthly figure.
Compound Interest & Future Value Calculator
Project balances from an opening sum and month-end deposits; compare future value, growth and contributions.
Retirement Goal Calculator
Estimate the portfolio required to cover a retirement spending gap.
Loan Payoff and Term Calculator
Reverse-solve payoff months from principal, annual rate and monthly payment.
Take-Home Pay Calculator
Estimate annual and monthly take-home pay after entered deductions.
Auto Lease Calculator
Estimate a lease payment from capitalized cost, residual and money factor.
Cap Rate Calculator
Calculate rental capitalization rate from income, vacancy, expenses and value.
Compare the cost as well as the payment
A smaller loan installment can come from spreading repayment over more months, even when principal and interest rate are unchanged, so judge the monthly saving alongside lifetime interest and any fees that the loan comparison includes. Check the repayment term first.
Compare two loan offers →Real numbers, not screenshots
Worked examples for common calculations
Each row is the figure that calculator produces at its own prefilled inputs, computed by the formula published on its page.
| Calculator | Worked-example inputs | Returns | Result |
|---|---|---|---|
| Loan Payment & Amortization Calculator | Loan amount $25,000, Annual interest rate 7.5%, Loan term 5.0 years | Monthly payment | $501 |
| Mortgage Payment Calculator | Home price $425,000, Down payment $85,000, Mortgage rate 6.5% | Estimated monthly housing cost | $2,816 |
| Compound Interest & Future Value Calculator | Starting amount $10,000, Monthly contribution $500, Expected annual return 7.0% | Future value | $300,851 |
| Retirement Goal Calculator | Desired annual retirement spending $80,000, Expected annual fixed income $30,000, Initial withdrawal rate 4.0% | Target retirement portfolio | $1,250,000 |
| Loan Payoff and Term Calculator | Amount borrowed $25,000, Annual interest rate 7.5%, Monthly payment $550 | Estimated payoff term | 54.0 months |
| Take-Home Pay Calculator | Annual gross salary $85,000, Federal effective tax rate 14.0%, State/local effective tax rate 5.0% | Estimated monthly take-home pay | $4,696 |
| Auto Lease Calculator | Negotiated vehicle price $42,000, Capitalized-cost reduction $3,000, Residual value $24,000 | Estimated monthly lease payment | $614 |
| Cap Rate Calculator | Annual gross rental income $48,000, Vacancy and credit loss 5.0%, Annual operating expenses $15,000 | Capitalization rate | 6.8% |
Open any calculator to replace these inputs with your own. Nothing is gated and no account is required.
Ways in
Whichever way you think about the decision
Choose a tool, a specific question, a comparison or a concept: every path lands on a calculator with its formula and sources on show.
Worked money questions
Computed answers to specific questions: the payment on a $350,000 mortgage at 6.5%, what a deposit grows to: each reproducible from the numbers shown.
↗02Comparison calculators
Hold a decision constant and put two alternatives on the same timeline: rent vs buy, 15- vs 30-year, Roth vs traditional and more.
↗03Calculators by category
Each category page lists its calculators with their worked-example results and answers the common questions for that topic, from loan rates to unit conversions.
↗04Financial guides
Plain-language background on the formulas, definitions, risks and tradeoffs behind the calculators.
↗05Glossary
Defined financial terms, each pointing to the calculator that puts it to work.
↗06Frequently asked questions
How the calculators work, what happens to the numbers you enter, and how the arithmetic is verified.
↗07Radius map calculator
Search an address or click the map, set a radius, and see the covered area and diameter instantly.
↗No account. No sales pitch.