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Financial decisions, made visible

Calculate the money.
Understand the tradeoff.

663 free calculators. Borrowing, mortgages, investing, retirement, fixed income, freelance work, business, taxes and household money. Results carry the formula, the assumptions, the limitations, the comparisons and the source trail.

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FINANCIAL RECORD / INVESTINGLIVE
Projected future value$300,851$10,000 start + $500 monthly · 7% · 20 years
Contributions$130,000
Est. growth$170,851
FormulaVisible
InputsPrivate
663working calculators
42money categories
100%formula visibility
0results behind a form

Beyond money

Calculators for health, math, home projects and daily life

Browse all 42 categories →
01

BMI Calculator

Calculate body mass index from height and weight.

02

Age Calculator

Calculate exact age in years and total days lived from a birth date.

03

Fraction Calculator

Add, subtract, multiply or divide two fractions and get the answer in lowest terms plus its decimal value.

04

Percentage Calculator

Calculate what percentage one number represents of another.

05

Paint Calculator

Estimate the gallons of paint a room needs from its size, doors, windows and coats.

06

MPG Calculator

Calculate miles per gallon, fuel cost per mile and liters per 100 km from a fill-up.

07

Time Card Calculator

Calculate hours worked and pay for a shift from start time, end time and unpaid break.

08

Sleep Calculator

Find bedtimes that let you wake at the end of a sleep cycle, from your wake-up time.

09

Electricity Cost Calculator

Calculate the kilowatt-hours and cost of running any appliance from its wattage, hours and your rate.

10

Tip Calculator

Calculate a tip, the final bill and an even per-person split for a group.

11

Length Converter Calculator

Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards and miles.

12

Trapezoid 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 →
  1. 01Freddie Mac PMMSWeekly national mortgage survey benchmarks.
  2. 02U.S. TreasuryOfficial daily par-yield curve observations.
  3. 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.

01

Loans & Payments

Compare payments, borrowing costs, terms and payoff strategies.

15 calculators02

Mortgage & Home

Estimate affordability, monthly ownership cost, equity and refinance tradeoffs.

45 calculators03

Investing & Returns

Model compounding, growth, income and investment returns.

55 calculators04

Retirement

Translate future spending into portfolio, contribution and income targets.

48 calculators05

Savings & Banking

Plan savings goals, reserves, yields, CDs and time to goal.

9 calculators06

Debt & Credit

Understand payoff time, interest, utilization and consolidation.

14 calculators07

Taxes & Paycheck

Create educational estimates for federal tax and take-home pay.

22 calculators08

Auto Finance

Compare vehicle payments, leases, depreciation and running costs.

18 calculators09

Real Estate Investing

Evaluate rental income, operating performance and leverage.

19 calculators10

Business Finance

Calculate margins, break-even volume, liquidity and runway.

62 calculators11

Education & Student Loans

Model student debt, college savings and education economics.

18 calculators12

Everyday Money

Handle percentages, discounts, pay conversions and inflation.

12 calculators13

Bonds & Fixed Income

Price bonds, compare yields and measure interest-rate sensitivity.

16 calculators14

Freelance & Self-Employed

Price independent work, plan taxes and replace employee benefits.

13 calculators15

Startup & SaaS

Model recurring revenue, retention, acquisition economics and ownership dilution.

14 calculators16

Household & Life

Plan insurance, healthcare, childcare, budgets and major life transitions.

24 calculators17

Body Composition

Estimate BMI, body fat, lean mass and other body-composition measures.

11 calculators18

Energy & Nutrition

Estimate calorie needs, macronutrient targets and energy expenditure.

9 calculators19

Fitness & Performance

Estimate training loads, heart-rate zones and pace.

7 calculators20

Clinical Estimates

Educational estimates for kidney function and blood alcohol concentration.

9 calculators21

Algebra & Arithmetic

Solve equations, simplify fractions and ratios, and work with exponents, roots and logs.

22 calculators22

Geometry

Calculate area, volume, surface area and distance for common shapes.

30 calculators23

Statistics & Probability

Calculate averages, spread, combinations, probability and confidence intervals.

13 calculators24

Number Theory & Precision

Calculate factors, multiples, scientific notation and measurement error.

9 calculators25

Date & Time

Calculate age, date differences, day of the week and countdowns.

6 calculators26

Unit Conversion

Convert length, weight, temperature, volume, speed and tire sizes.

19 calculators27

Home & Construction

Estimate material, tile, roofing and square footage for a project.

17 calculators28

Science & Electronics

Calculate circuits, density, molarity and voltage drop.

16 calculators29

Weather

Calculate wind chill, heat index and dew point using the official National Weather Service formulas.

5 calculators30

Plumbing

Size pipe, flow, drainage and water heating for common residential plumbing tasks.

6 calculators31

HVAC

Estimate duct sizing, airflow, equipment tonnage and static pressure for heating and cooling systems.

5 calculators32

Electrical Trade

Size conduit, wire, transformers and boxes using standard NEC reference calculations.

5 calculators33

Concrete & Masonry

Estimate concrete, rebar, block and footing quantities for common construction projects.

5 calculators34

Carpentry

Calculate rafter, stair, framing and decking dimensions for common carpentry projects.

6 calculators35

Machining

Calculate feeds, speeds, tap drill sizes and thread engagement for machine shop work.

4 calculators36

Craft & Sewing

Estimate yarn, fabric, binding and pattern-scaling quantities for knitting, crochet and sewing projects.

6 calculators37

Networking & Technology

Calculate IP subnets, password entropy, file transfer time and digital storage conversions.

7 calculators38

Physics & Mechanics

Work out speed, force, energy, motion, waves and gas behavior from the standard physics formulas.

14 calculators39

Time & Clock

Work out sleep times, hours worked, time differences, time zones and military time.

8 calculators40

Cooking & Kitchen

Scale recipes, compare pan sizes, dial in a coffee ratio and price a serving.

4 calculators41

Energy & Utilities

Price appliance electricity, EV charging and fuel economy, and size a battery for a load.

8 calculators42

Lawn & Garden

Order mulch, topsoil, gravel, sand, seed and sod, and plan fertilizer and watering for a yard.

8 calculators

Popular starting points

Answer the next money question

View all 663 tools →
Loans & Payments

Loan Payment Calculator

Calculate the monthly payment and total interest for a fixed-rate installment loan.

Open calculator →
Mortgage & Home

Mortgage Payment Calculator

Estimate principal, interest, property tax, insurance and HOA in one monthly figure.

Open calculator →
Investing & Returns

Compound Interest Calculator

Project future value from a starting investment, monthly contributions and return.

Open calculator →
Retirement

Retirement Savings Calculator

Project an existing retirement balance plus monthly contributions.

Open calculator →
Debt & Credit

Credit Card Payoff Calculator

Estimate payoff time and interest for a card balance and fixed payment.

Open calculator →
Taxes & Paycheck

Take-Home Pay Calculator

Estimate annual and monthly take-home pay after entered deductions.

Open calculator →
Auto Finance

Auto Loan Calculator

Calculate monthly payment and total interest on a vehicle loan.

Open calculator →
Real Estate Investing

Cap Rate Calculator

Calculate rental capitalization rate from income, vacancy, expenses and value.

Open calculator →

Trust is part of the answer

Every result has an audit trail

Free Calculators Online separates arithmetic from interpretation. A number never has to be taken on faith here. Each page shows the formula that produced its result. Every input is defined in plain language. The worked example runs on prefilled values, not an assumed average. Limitations are stated where the model stops being a reasonable approximation. Sources are cited at the definition or rule level, not as a general endorsement. A review date shows when the calculation was last checked. Core formulas are also recomputed a second, independently coded way, a month-by-month simulation checked against a closed-form loan payment, for example, so a shared error in one implementation cannot pass unnoticed through the other. Nothing here is financial, tax or legal advice: the site publishes arithmetic and its assumptions, and leaves the decision itself to the reader holding their own numbers.

Read the methodology →
  1. 01DefineScope, units, timing and assumptions are explicit.
  2. 02CalculateDeterministic formulas are tested at normal and boundary inputs.
  3. 03CompareSaved scenarios and sensitivity checks expose the important lever.
  4. 04VerifySources, limitations, update date and correction route stay visible.

Real numbers, not screenshots

What the most-used calculators return

Each row is the figure that calculator produces at its own prefilled inputs, computed by the formula published on its page.

Worked-example results from eight of the 663 Free Calculators Online calculators.
CalculatorWorked-example inputsReturnsResult
Loan Payment CalculatorLoan amount $25,000, Annual interest rate 7.5%, Loan term 5.0 yearsMonthly payment$501
Mortgage Payment CalculatorHome price $425,000, Down payment $85,000, Mortgage rate 6.5%Estimated monthly housing cost$2,816
Compound Interest CalculatorStarting amount $10,000, Monthly contribution $500, Expected annual return 7.0%Future value$300,851
Retirement Savings CalculatorStarting amount $20,000, Monthly contribution $800, Expected annual return 7.0%Future value$1,138,307
Credit Card Payoff CalculatorCard balance $8,000, Card APR 22.9%, Monthly payment $300Months to payoff37.6 months
Take-Home Pay CalculatorAnnual 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 Loan CalculatorLoan amount $35,000, Annual interest rate 6.5%, Loan term 6.0 yearsMonthly payment$588
Cap Rate CalculatorAnnual gross rental income $48,000, Vacancy and credit loss 5.0%, Annual operating expenses $15,000Capitalization rate6.8%

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

Start from the tool, a specific question, a comparison or a concept: every path lands on a calculator with its formula and sources on show.

01

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.

02

Comparison 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.

03

Questions, answered

Direct answers to common money questions, each stating the formula it comes from and the figure that formula produces.

04

Financial guides

Plain-language background on the formulas, definitions, risks and tradeoffs behind the calculators.

05

Glossary

Defined financial terms, each pointing to the calculator that puts it to work.

06

Frequently asked questions

How the calculators work, what happens to the numbers you enter, and how the arithmetic is verified.

07

Radius 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.

Put a number behind your next decision.

Find your calculator