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Unit converter — length, mass, volume, area, speed, temperature

Convert a measurement to the units you need for a recipe, specification or comparison. Choose from length, mass, volume, area, speed and temperature, with the conversion factor or formula shown.

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Result—
1 m = 3.2808399 ft

Conversion factors follow widely used standards (NIST SP 811). Temperature conversions are exact identities.

Popular conversions

Open a conversion page for a reference chart, formula and worked examples.

Centimetres to Inches ×0.394 Inches to Centimetres ×2.54 Millimetres to Inches ×0.039 Inches to Millimetres ×25.4 Metres to Feet ×3.281 Feet to Metres ×0.305 Kilometres to Miles ×0.621 Miles to Kilometres ×1.609 Kilograms to Pounds ×2.205 Pounds to Kilograms ×0.454 Grams to Ounces ×0.035 Ounces to Grams ×28.35 Celsius to Fahrenheit Fahrenheit to Celsius Celsius to Kelvin Kelvin to Celsius Litres to US gallons ×0.264 US gallons to Litres ×3.785 Millilitres to US fluid ounces ×0.034 US fluid ounces to Millilitres ×29.574 Kilometres per hour to Miles per hour ×0.621 Miles per hour to Kilometres per hour ×1.609 Knots to Miles per hour ×1.151 Square metres to Square feet ×10.764 Square feet to Square metres ×0.093 Acres to Hectares ×0.405 Hectares to Acres ×2.471

How to use

  1. Pick a category — length, mass, volume, area, speed or temperature. This keeps unlike quantities, such as ounces of mass and fluid ounces of volume, separate.
  2. Enter a value and choose the unit you are converting from.
  3. Choose the target unit. The result updates instantly — there is no convert button.
  4. Use the swap button to exchange the units. It keeps the entered number, so enter the previous result as well if you want to check a round trip.

For example, 254 cm is 100 inches, while 20 °C is 68 °F. Temperature needs an offset: 20 × 9 ÷ 5 + 32 = 68. See NIST’s conversion tables for reference factors.

Questions

Which conversion factors do you use?

The tables use standard conversion factors, including exactly 0.3048 metres per international foot and 0.45359237 kilograms per pound. Some stored factors are rounded, such as 0.514444 m/s per knot. Temperature conversion includes the offset between scales, not just a multiplier.

Why are US and UK gallons different?

A US liquid gallon is 3.785411784 L, while an imperial gallon is 4.54609 L, about 20% larger. Select gal (US) or gal (UK) to match the source measurement. The same need to check the system applies to pints and fluid ounces.

Why can a small result display as zero?

Results show up to six decimal places. A smaller non-zero value can round to zero on screen and in copied output. Choose a smaller target unit if you need a readable value; the displayed digits do not establish the precision of the original measurement.

Can I convert millilitres to grams?

Not with a unit factor alone. Millilitres measure volume and grams measure mass; the relationship depends on the material’s density. Use an ingredient-specific conversion for food rather than treating every millilitre as a gram.

Examples and checks

Choose the measurement category, then the starting and destination units. An ounce of weight and a fluid ounce of volume are different measurements; this converter does not treat them as interchangeable.

Convert a length

Input or situation
254 centimetres to inches
Result
100 inches

One inch is exactly 2.54 centimetres, so 254 ÷ 2.54 = 100.

Convert a temperature

Input or situation
20 °C to °F
Result
68 °F

The calculation is 20 × 9 ÷ 5 + 32. The added 32 matters as well as the multiplication.

Before you use the result

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Read more

Guide Ounces vs fluid ounces: choose the scale or the measuring jug Convert ounces to grams and fluid ounces to millilitres, distinguish US and imperial measures, and check ambiguous recipe quantities before measuring. Guide US, UK and metric cups: which measure does your recipe need? Check a recipe's cup size, convert liquids into millilitres, and understand when a larger cup changes the proportions rather than just the batch size. Guide Why a cup of flour and a cup of honey are not the same weight Find a useful cups-to-grams estimate, check the ingredient and cup size, and avoid packing or sifting changes that alter a baking measurement.

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