One converter for the everyday six: length, weight, temperature, volume, area, and speed — 46 units, converted instantly as you type, using the exact factors from the international definitions rather than rounded approximations. The formula line shows the multiplier, so every result is checkable.
How to convert units
- Pick a category, then the from and to units — the common pair is preselected.
- Type your value; the result updates on every keystroke.
- ⇄ Swap flips the direction instantly.
- Check the grey line under the result: it shows
1 unit = …and the exact multiplier used.
Why “exact” is worth saying
Most unit factors aren’t measurements — they’re definitions. Since the 1959 International Yard and Pound Agreement, one inch is 25.4 mm, one foot is 0.3048 m, one pound is 0.45359237 kg, exactly, with zero uncertainty. Converters disagree only when they round those factors or mix up siblings: the US gallon (3.785 L) versus the UK imperial gallon (4.546 L) is the classic trap, which is why the two are separate, labeled units here. Cooking measurements (cups, tablespoons) use the US customary definitions — noted in the unit names — because that’s what most recipes mean.
Temperature plays by different rules
Celsius, Fahrenheit, and Kelvin differ by an offset, not just a scale factor — 0 °C sits at
32 °F, and the size of a degree differs too. That’s why temperature shows a formula
(°F = °C × 9⁄5 + 32) instead of a multiplier, and why the anchor points are worth memorizing:
water freezes at 0 °C / 32 °F, boils at 100 °C / 212 °F (at sea level), and −40° is the one
temperature where both scales agree.
Private by design
Conversions are computed on your device the moment you type — no lookup service, no request, no logging. It works offline once the page is loaded.