Calculators that give you the number, then explain it
Every tool here loads instantly, shows the formula it used, and follows up with a plain guide to the numbers you just entered. Nothing you type leaves your browser.
30 calculators and converters, plus 611 date questions answered directly.
Browse by category
Date & Time
Work out a date, an age, or the hours between two times.
Finance & Loans
Payments, interest, payoff dates and what a loan really costs.
Home & Construction
Materials, quantities and quotes for work around the house.
Math & Statistics
Percentages, fractions and the arithmetic behind them.
Education & Grades
Course grades, exam scores and what you still need.
Sizes & Units
Convert between measurement systems without guessing.
Auto & Travel
Fuel economy, running costs and the price of a journey.
Health & Fitness
The formula is on the page
Every tool states the maths it used, so you can check it rather than trust it.
Your numbers stay with you
The calculators run in your browser. Nothing you enter is sent to us, stored or logged.
Written for after the answer
Each page explains what the figure means, where it goes wrong, and when not to rely on it.
Every tool
- Age Calculator
- Amortization Calculator
- BMI Calculator
- BMR Calculator
- Body Fat Calculator
- Bra Size Calculator
- BTU Calculator
- Concrete Calculator
- Credit Card Payoff Calculator
- Final Grade Calculator
- Fraction Calculator
- Gas Mileage Calculator
- Gravel Calculator
- Home Equity Loan Calculator
- Hours Calculator
- Lease Calculator
- Mulch Calculator
- One Rep Max Calculator
- Pace Calculator
- Percent Off Calculator
- Percentage Calculator
- Retirement Calculator
- Roman Numeral Converter
- Roofing Calculator
- Salary Calculator
- Shoe Size Conversion
- Square Footage Calculator
- Stair Calculator
- Tile Calculator
- Time Calculator