Unit Converter
Enter a value once and see it converted to every unit in that category at the same time — no need to pick a "to" unit first. Covers length, weight, temperature, volume, area, speed, time, and data storage.
Metric, imperial, and why both still exist
Most of the world standardized on the metric system (meters, kilograms, liters) because its units scale by powers of ten, which makes conversion and calculation simple. The United States still primarily uses the U.S. customary system (inches, pounds, gallons), a close relative of the older imperial system Britain used before switching to metric — which is why the two aren't always identical (a US gallon and a UK gallon, for instance, are different sizes).
Frequently asked questions
How accurate are these conversions?
Length, weight, volume, area, and speed use the internationally defined exact conversion constants (for example, 1 inch = exactly 2.54 cm by international agreement since 1959), so those are exact to the precision shown. Time's "month" and "year" units are calendar averages (30.4375 and 365.25 days), since actual months and years vary in length.
What's the difference between kB and KiB?
kB (kilobyte) uses the decimal definition, 1,000 bytes, the same convention as kilometers or kilograms. KiB (kibibyte) uses the binary definition computers actually use internally, 1,024 bytes. The gap compounds at larger sizes: a "1 TB" hard drive (1012 bytes, decimal) shows up as roughly 931 GiB in an operating system that reports binary units, which is the usual explanation for a new drive "missing" storage.
Why do US and UK volume units differ?
The US customary gallon and the UK imperial gallon were standardized separately and are different sizes — a US gallon is about 3.79 liters, while a UK gallon is about 4.55 liters, roughly 20% larger. The same split applies to pints, quarts, and fluid ounces, which is why this converter lists US and UK volume units separately.
Is a US ton the same as a UK ton?
No. A US ("short") ton is 2,000 pounds, a UK ("long") ton is 2,240 pounds, and a metric tonne is 1,000 kg (about 2,204.6 pounds) — three different units that are easy to mix up because they share a name.
Why does temperature work differently from the other categories?
Every other category here is a straight multiplication (2 inches is always exactly 5.08 cm). Temperature scales also have different zero points — 0°C is 32°F, not 0°F — so converting between them takes an offset as well as a scale factor.