Instant Unit Converter — free live unit converter

Every unit stores a single conversion factor relative to a shared base unit (e.g. grams for weight, seconds for time). When you type in any field, the value is converted to that base and then propagated to every other field in real time — no dropdowns, no submit button needed.

Linear conversions (length, weight, area, volume, time) use internationally-defined exact factors (e.g. 1 inch = 2.54 cm exactly). Results are displayed rounded to 8 significant figures in full decimal notation. Number-system conversions (binary, octal, hex) use BigInt arithmetic so there is zero precision loss even for very large integers.

Unlike length or weight, temperature scales have both different zero points and different step sizes. Internally, Kelvin is used as the base: input is first converted to Kelvin, then projected to every other scale. The formulas are: °C = K − 273.15 and °F = (K − 273.15) × 9/5 + 32.

Binary (base 2), Octal (base 8), Decimal (base 10), and Hexadecimal (base 16). Hex input is case-insensitive. If you type an invalid digit for the selected base the field turns red and other fields stay clear until the input is valid.

Completely free, no account needed. All conversions run entirely in your browser — no data is ever sent to a server. The conversion math itself works fully offline after the page loads.

Yes. The tab bar scrolls horizontally on small screens, unit cards stack into a single column, and numeric inputs use inputmode=decimal to trigger the number keypad on iOS and Android.