THE CALCULATOR LIBRARY

All calculators

Free calculators for money, health, math, and everyday life. Find the right tool for your next question.

Always freeNo account neededFormulas explained
Student tools

Grades, finals & GPA

Check where you stand, work out what you need, and plan your next semester.

Calculate a grade from earned and possible points

Plan, save, and make more informed money decisions.

Finance

Explore finance

Retirement

Mortgage and Real Estate

Auto

Investment

Other

Tax and Salary

Understand your health and everyday wellness goals.

Health & fitness

Explore health & fitness

Fitness

Other

Pregnancy

Work through the numbers, one clear step at a time.

Math

Explore math

Geometry

Statistics

Arithmetic and Number Theory

Useful tools for life's little questions and big projects.

Everyday

Explore everyday

Date and Time

Internet

Everyday Utility

Housing/Building

Various Measurements/Units

Weather

Entertainment/Anecdotes

Electronics/Circuits

Transportation

Spin wheels

Leave a little to chance.

Pick a name, settle a choice, or find your next idea with a spin.

Explore spin wheels
Time & clocks

Make time work for you.

Plan a call, check a date, or focus on what comes next.

Explore time tools

Choosing an online calculator

Start with the quantity you want to find and the information you already know. Financial calculators model money over time; health calculators provide limited reference estimates; math tools solve numerical relationships; everyday tools handle dates, units, and practical quantities. Each tool shows its supported inputs and method so you can check whether it fits the problem.

Read the formula and worked example before comparing results. Use matching units and time periods, and keep assumptions visible when trying another scenario. A calculation can be mathematically correct while still answering a different question from the one you intended.

Compare the questions

Choose a methodInputsMethod
Compound Interest Calculator

Savings growth

  • Starting amount ($)
  • Regular contribution ($)
  • Contribution frequency
  • Nominal annual return (%)
  • Time horizon (years)
  • Compounding per year
  • Contribution timing
  • Tax rate on annual interest (%)
  • Annual inflation assumption (%)

Each period: balance grows at the equivalent periodic rate, then a contribution is added (or added first for beginning-of-period deposits).

How it works
BMI Calculator

Adult BMI

  • Measurement system
  • Weight (kg)
  • Height (cm)
  • Age (years)

BMI = weight in kilograms / (height in meters)².

How it works
Percentage Calculator

Percentage of a number

  • Percentage (%)
  • Number

Result = percentage ÷ 100 × number.

How it works
Date Calculator

Between two dates

  • Start date
  • End date
  • Include end date

Calendar-day difference uses date-only values, independent of daylight-saving changes.

How it works