MultiKit

Unit Converter: Length, Weight, Temperature, Area, Volume and More

  • Free
  • No sign-up
  • Runs in your browser
  • Version 1.0.2
  • Last updated 2026-10-25
Report a problem

Pick a kind, type a value and a unit, and see it in every other unit of that kind at once.

Results keep 8 significant digits, or as many as the number you typed. US units (cup, gallon, fluid ounce) are the US definitions.

Everything you enter is processed in your browser and is never sent to a server.

How to use

  1. Choose the kind of quantity, such as length or temperature.
  2. Type the value and choose the unit it is in. All the other units of that kind update as you type.
  3. Press Copy next to the result you need.

Examples

1 inch
→ 2.54 centimeters
100 degrees Celsius
→ 212 degrees Fahrenheit
Temperatures need an offset, not just a multiplication, and the tool handles it.
1 mile
→ 1.609344 kilometers

How it works

Conversions are done by the open-source js-quantities library, which keeps each unit as an exact multiple of a base unit (meter, kilogram, second, kelvin) and handles the offsets of temperature scales. Every unit in the list is checked to belong to the right kind, and every pair of units of a kind is checked by converting there and back, which should return the starting number.

Results are rounded to 8 significant digits for display. Some of the library’s constants, such as the tablespoon, are rounded themselves, so their ratios (3 teaspoons to a tablespoon) are right only to about 9 digits, and showing 8 keeps that noise out of sight.

Sources

Frequently asked questions

Are the conversions exact?
They use the official definitions: an inch is exactly 2.54 centimeters, a pound exactly 0.45359237 kilograms and a mile exactly 1,609.344 meters. The results are shown with 8 significant digits, or as many as the number you typed.
Which gallon and cup does it use?
The US ones: a US gallon is 3.7854118 liters and a US cup about 236.59 milliliters. The UK (imperial) gallon is different and is not included, so use it only for US recipes and US fuel figures.
How is temperature converted?
Celsius, Fahrenheit and Kelvin are converted with their real formulas, such as F = C × 9/5 + 32, so 0 °C is 32 °F and -40 °C equals -40 °F.
Why are some units missing?
The list is kept to units people actually look up. For data sizes such as MB and GiB, use the data size converter. For Korean area units, the pyeong converter turns 평 into square meters and back.
Is anything sent anywhere?
No. The conversion runs in your browser.

Guides

Version history
  • 1.0.2 — Makes the search title and description state the supported task, key formats and privacy benefit more clearly.
  • 1.0.1 — Fixes a narrow screen keeping a label and its own field on the same line, instead of wrapping them apart (Value's label on one line, its box on the next).
  • 1.0.0 — First release.

Last updated: