Why the definitions matter
Most converters give you a number without telling you which standard produced it. That is fine for metres to feet, and dangerous for gallons, cups, ounces and storage sizes — where two legitimate standards differ by up to 20%.
Mensura states its assumptions on every page. Where a unit has competing definitions, the tool says which one it uses and why, so you can tell whether that matches your source.
Everything runs in your browser
No account, no upload, no server round trip. Calculations happen locally, which means they work offline once the page has loaded and your inputs never leave your device.
Exact factors, honest precision
Conversions use exact definitions — an inch is 25.4 mm by international agreement, a pound is 453.59237 g — so results are reproducible rather than approximated.