Unit conversions come up constantly, from recipes to engineering. These tools convert accurately between metric and imperial in both directions, using exact factors so the result is precise to the last decimal.
Every tool here is free, works instantly in your browser, and never stores the numbers you enter. They give reliable results for everyday use — treat anything high-stakes as a starting point and double-check with a professional.
Frequently asked questions
Yes. Every conversion calculator on OnlineCalculators.com is completely free, with no sign-up, account, or app required.
Yes. Each converter uses the internationally defined factor for that unit, so the result is accurate. Where a value is irrational (like inches to centimetres) we keep full precision before rounding the display.
No. Every calculation runs entirely in your browser — the figures you type are never sent to or stored on a server.