Unit Converter

Convert length, weight, temperature, volume, time, speed, and area between metric, US, and imperial units. Instant, client-side.

Runs in your browser — nothing uploaded
1 m equals
1,000 mm
Millimeter
100 cm
Centimeter
0.001 km
Kilometer
39.37008 in
Inch
3.28084 ft
Foot
1.093613 yd
Yard
0.000621371 mi
Mile
0.000539957 nmi
Nautical mile

A single converter for the everyday units you keep looking up — kilograms to pounds, kilometres to miles, Celsius to Fahrenheit, litres to gallons, and the rest. Pick a category, type a value, see everything else at once.

Private by design — your data never leaves your device

How to use it

No account, no upload — it all happens on your device.

1
Pick the category — length, weight, temperature, and so on.
2
Choose the source unit and type a value.
3
Pick the target unit. The converted value updates instantly, and the full conversion table below shows every other unit.

Quick reference

The conversions people search for most.

  • 1 inch = 2.54 centimetres
  • 1 foot = 30.48 centimetres
  • 1 mile = 1.609 kilometres
  • 1 pound = 0.4536 kilograms
  • 1 ounce = 28.35 grams
  • 0 °C = 32 °F (water freezes)
  • 100 °C = 212 °F (water boils at sea level)
  • 1 US gallon = 3.785 litres
  • 1 acre = 4047 square metres
  • 1 knot = 1.852 km/h

A note on units

Temperature is the trickiest category because the conversion is affine, not multiplicative. Celsius and Fahrenheit share no common zero; Kelvin offsets from Celsius by 273.15; Rankine offsets from Fahrenheit by 459.67. We use the exact formulas rather than approximations so 0 °C lands precisely on 32 °F.

For time, "month" is treated as 30 days and "year" as 365 days. Calendar-accurate dates need a different tool — see the Unix Timestamp Converter for those.

US and Imperial gallons are different sizes — the imperial gallon (UK) is roughly 20% larger than the US gallon. Both are available so you don't have to guess which one a recipe or spec sheet means.

Frequently asked

Which categories are supported?
Length, weight, temperature, volume, time, speed, and area. Each category has the units you reach for most often — SI metric plus the common US/Imperial units.
How accurate are the conversions?
Inside-browser arithmetic, no rounding to a fixed number of decimals. The displayed precision adapts to the size of the result; small numbers show more decimals, large numbers fewer. For temperature, exact affine formulas are used (no lossy lookup tables).
Is anything sent to a server?
No. Every conversion runs as plain JavaScript in your browser. Values you type never leave your device.

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