Free online calculators for finance, health, math & more
Instant results, clear explanations, mobile-friendly design. Everything you need to run the numbers — in one place.
Calculator categories
Pick a category and dive into dozens of tools.
Financial
Mortgages, loans, investments, retirement and everyday money math.
15 calculators
Health & Fitness
BMI, calories, macros, pregnancy and fitness planning tools.
11 calculators
Math
Percentages, fractions, statistics, geometry and scientific tools.
11 calculators
Conversions
Length, weight, temperature, currency and unit converters.
10 calculators
Start with these
Our most-loved calculators — accurate, fast, and beautifully simple.
Mortgage Calculator
Estimate monthly mortgage payments with taxes and insurance.
Compound Interest Calculator
See the power of compounding over time.
BMI Calculator
Calculate your Body Mass Index instantly.
Percentage Calculator
Percent of, percent change, and percent increase.
Length Converter
Convert between meters, feet, inches, miles and more.
What people are using now
Mortgage Calculator
Estimate monthly mortgage payments with taxes and insurance.
Loan Calculator
Calculate monthly payments for any fixed-rate loan.
Compound Interest Calculator
See the power of compounding over time.
BMI Calculator
Calculate your Body Mass Index instantly.
Calorie Calculator
Find your daily calorie needs based on activity.
Percentage Calculator
Percent of, percent change, and percent increase.
Length Converter
Convert between meters, feet, inches, miles and more.
Weight Converter
Convert kg, lb, oz, stones and grams.
Temperature Converter
Convert Celsius, Fahrenheit and Kelvin.
Recently added
Savings Calculator
Reach your savings goal with a monthly plan.
ROI Calculator
Calculate return on investment as a percentage.
Water Intake Calculator
Daily water target based on weight and activity.
Currency Converter
Convert between major world currencies.
Instant results
Every calculator updates as you type. No 'submit' button, no waiting.
No sign-up
Nothing tracked, nothing stored. Numbers stay in your browser.
Formulas explained
Each tool shows the exact math so you can trust the answer.
Guides that make the numbers make sense
Every calculation on CalcHub has a plain-English explainer. Understand mortgages, compound growth, BMI, and unit conversions in minutes.
Read the blogHow mortgage payments really work
The amortization formula, in plain English.
Compound interest, visualized
Why time matters more than rate.
What your BMI actually means
And what it doesn't.
The 5 unit conversions you'll always need
Metric ↔ Imperial cheat sheet.