Unit Converters

4 free online tools — Convert between any units instantly

Convert between metric, imperial and US units for length, weight, temperature, area, volume, speed, time and data storage — with hundreds of direct pages for the pairs people actually search for, like kilograms to pounds and Celsius to Fahrenheit. Specialised converters cover cooking measurements by ingredient, Roman numerals and time zones.

Cooking Measurement Converter Convert cups, spoons, grams and ounces for the ingredient you are actually using — because a cup of flour and a cup of honey do not weigh the same. Roman Numeral Converter Convert any number to Roman numerals and any numeral to a number — with the bar notation above 3,999 and strict checking of malformed numerals. Time Zone Converter Pick a time in one zone and see it in as many others as you like, with the date shift and DST handled for you. Unit Converter Convert between hundreds of units across eight measurement categories.

Popular conversions

Length

mm → cm mm → m mm → km mm → in mm → ft mm → yd mm → mi cm → mm cm → m cm → km cm → in cm → ft cm → yd cm → mi

Weight

g → kg g → oz g → lb g → st kg → g kg → oz kg → lb kg → st oz → g oz → kg oz → lb oz → st lb → g lb → kg

Temperature

°C → °F °C → K °F → °C °F → K K → °C K → °F

Data

B → KB B → MB B → GB B → TB B → KiB B → MiB B → GiB B → bit KB → B KB → MB KB → GB KB → TB KB → KiB KB → MiB

Area

cm² → m² cm² → km² cm² → ha cm² → in² cm² → ft² cm² → ac cm² → mi² m² → cm² m² → km² m² → ha m² → in² m² → ft² m² → ac m² → mi²

Volume

ml → L ml → m³ ml → tsp ml → tbsp ml → fl oz ml → cup ml → pt ml → gal ml → gal UK L → ml L → m³ L → tsp L → tbsp L → fl oz

Speed

m/s → km/h m/s → mph m/s → kn km/h → m/s km/h → mph km/h → kn mph → m/s mph → km/h mph → kn kn → m/s kn → km/h kn → mph

Time

ms → s ms → min ms → h ms → d ms → wk ms → mo ms → yr s → ms s → min s → h s → d s → wk s → mo s → yr

Start here

  • The unit converter handles every unit in one place, with the formula shown.
  • The cooking converter turns cups into grams per ingredient, because a cup of flour and a cup of honey weigh very different amounts.
  • The Roman numeral converter goes both ways and explains why IIII is a clock-face exception.
  • The time zone converter compares several zones at once with correct daylight-saving offsets.

Exact factors, no rounding surprises

Conversion factors here are the defined values — an inch is exactly 25.4 mm, a pound exactly 0.45359237 kg — and results are shown to a sensible precision rather than a false fifteen decimals. Temperature is the one conversion that is not a simple multiplication: the offset between Celsius and Fahrenheit is why 0 °C is 32 °F, and the converter treats it correctly. For US versus imperial, remember that pints, gallons and fluid ounces differ between the two systems by up to 20%; the tools label which is which.

The long-tail pages

Each popular pair — metres to feet, kilometres to miles, grams to ounces, litres to gallons — has its own page with a direct answer, a worked example and a reference table, so a search lands on the conversion rather than a generic form. Browse them from the unit converter or the list below.