About

Online Calculators is a free collection of 210+ single-purpose calculators covering health, money, home improvement, cars, math, cooking and everyday life. The idea is simple: you have one specific question — what's my BMI, how many tiles do I need, what's 15% of 240 — and you should be able to get a straight, accurate answer in a few seconds without creating an account or downloading anything.

How the calculators work

Every calculator runs entirely in your browser using standard, published formulas (things like the Mifflin-St Jeor equation for calorie needs, or the standard loan amortization formula for mortgages). Nothing you type is sent to a server — the math happens on your device the moment you enter a number.

Accuracy

We aim for correct, standard formulas throughout, and note the source or method on calculators where it matters (for example, the Cooper test for VO2 max, or Naegele's rule for a pregnancy due date). That said, results are estimates for general informational purposes. For anything medical, financial, legal or safety-related, please confirm with a qualified professional before relying on the number.

Feedback

Found a calculator that needs fixing, or have an idea for one we're missing? Get in touch.