About Us

KitQuarter is a free library of online calculators for math, finance, health, dates, units and everyday life. Every tool runs entirely in your browser — no sign-up, no downloads, no waiting.

What we believe

A calculator should answer one question well and show its work. That is why every KitQuarter tool includes the exact formula it uses, a worked example with real numbers, and plain-language FAQs — so you can trust the result or verify it yourself.

How our calculators are built

• Real formulas, tested code. Each calculation is implemented from documented domain formulas and covered by automated unit tests for normal values, edge cases and invalid input.
• Validated input. Missing values, zero denominators and out-of-range numbers produce clear error messages — never a silently wrong answer.
• Private by design. Your numbers never leave your device. We don't require accounts and we don't sell data (see our privacy policy).

What's next

We publish new calculators every day — from percentage and loan calculators to BMI, age and unit converters. Browse the directory to see the full collection.

Get in touch

Found a bug, want a specific calculator, or spotted a wrong result? Contact us — we read every message sent to contact@kitquarter.com.