It converts a value from one unit to another — kilometers to miles, kilograms to pounds, Celsius to Fahrenheit, gigabytes to megabytes, and so on. Pick a category, type a number, and the result updates instantly.
How do I use it?
Pick a category at the top (Length, Weight, Temperature, etc.).
Type a number in the From box and choose its unit.
Choose the unit you want in the To box — the answer appears as you type.
You can also type into the To box to convert in reverse, or hit ⇅ Swap to flip the two units.
What can it convert?
Eleven categories: Length, Weight / Mass, Temperature, Area, Volume, Speed, Time, Digital storage, Pressure, Energy, and Angle. Each category has all the everyday units plus a handful of specialist ones.
Accuracy
How accurate are the results?
Conversions use exact, internationally-defined factors wherever they exist — for example 1 inch = 0.0254 m, 1 pound = 0.45359237 kg, and 1 US gallon = 3.785411784 L are all exact by definition. Results are shown to 8 significant figures, so extremely large or small numbers switch to scientific notation (e.g. 1.23e-5).
US or Imperial gallons?
The Volume category lists both. Plain "US gallon", "US quart", "US pint", "US cup", "US fluid ounce", "tablespoon" and "teaspoon" are US customary units. "Imperial gallon" is the UK gallon (4.54609 L). Pick whichever matches your recipe or spec.
KB vs KiB — what's the difference?
In Digital storage, KB / MB / GB / TB are decimal (powers of 1000, as drive manufacturers use), while KiB / MiB / GiB / TiB are binary (powers of 1024, as operating systems often report). That 1000-vs-1024 gap is why a "1 TB" drive shows up as about 931 GiB.
How are Month and Year handled in Time?
A month is treated as 30 days and a year as 365 days for a quick estimate. Calendar months and leap years vary, so use those two with that in mind.
Privacy & offline use
Where is my data stored?
Nowhere. Every calculation happens in your browser using plain JavaScript — nothing is sent to a server. The page loads once and then works entirely on your device.
Does it need an internet connection?
Only to load the page the first time. After that the math runs locally, so it keeps working even on a flaky connection.
