What we do

What The Calc is a set of 12 free calculators and converters for everyday questions: percentages, BMI, daily calories, age, compound interest, GPA, tips and aspect ratios, plus converters for units, time zones, cooking measurements and currencies.

Every tool is available in English, Spanish, French, Chinese and Japanese. There is no sign-up and nothing to install. Results update as you type, so you can get an answer in seconds.

The site is private by design. Calculations run entirely in your browser, and the numbers you enter are never sent to our servers.

How we keep results accurate

Each tool uses published, widely accepted formulas and standard conversion factors, such as the World Health Organization's adult BMI categories, the Mifflin-St Jeor equation for calorie needs and exact definitions like 1 inch = 2.54 cm. The currency converter uses daily reference rates from central banks and other official sources.

Each tool page explains the formula it uses, so you can check how a result was reached.

A note on using the results

Our results are for general information only. Health tools give estimates, not medical advice, and finance tools give illustrations, not financial advice. For important decisions, check with a qualified professional.