175 free calculators · none asks you to sign up
The right number, explained step by step
Type your numbers and get the result instantly — with the formula in the open, a chart, an example and the sources behind it.
- Tested formulas
- Cited sources
- No sign-up
What do you need to figure out?
Say it in your own words — we take you to the right tool.
Most popular
175 toolsMortgage
Calculate your monthly mortgage payment from the home price, down payment, interest rate and term — and see the full amortization: how much you pay in interest and how slowly the balance falls.
CalculateCompound Interest
See how compound interest grows your money over time, with an optional monthly contribution. Compare what you put in against what the interest adds.
CalculateBMI
Calculate your BMI (Body Mass Index), see the WHO classification and the healthy weight range for your height. Switch between metric (kg/cm) and imperial (lb/in).
CalculateSales Tax
Add sales tax to a price, or work backwards from a tax-inclusive total to find the price before tax. Enter any rate — it works for US sales tax, VAT or GST.
CalculatePercentage
Work out percentages three ways: what is X% of a number, what percent one number is of another, and finding the whole from a part and its percentage.
CalculateRatio
Simplify a ratio to its lowest terms, or solve a proportion to find a missing value. Enter two numbers to reduce A:B, or add a third to solve A:B = C:?.
CalculateInches → cm
Convert inches to centimeters instantly. Multiply by 2.54 — the relation is exact. Works both ways, with a quick reference table for common inch sizes.
CalculateCurrency Converter
Convert between the US dollar, euro, pound, yen and other major currencies. Use the reference rates for a quick estimate, or enter today rate for an exact figure.
CalculateRunning Pace
Find your running pace per mile and per kilometer from a distance and a finish time, plus your speed — and predicted times for the 5K, 10K, half and full marathon.
CalculateGPA
Calculate your GPA on the 4.0 scale from your letter grades and credit hours. Enter grades like A, B+, A- and the credits for each course to get a credit-weighted GPA.
Calculate