Unit Converter

Convert between metric and US units in one place: length, weight, volume, temperature, area, speed and digital storage. Results update as you type.

Result
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All conversions

How to use the unit converter

  1. Choose the type of measurement, such as Length or Temperature.
  2. Enter a value and pick the unit you are converting from and to.
  3. The answer appears instantly, along with the same value in every other unit of that type.

Common conversions

FromToMultiply by
InchesCentimeters2.54
FeetMeters0.3048
MilesKilometers1.609344
PoundsKilograms0.45359237
OuncesGrams28.3495
US gallonsLiters3.78541
US cupsMilliliters236.588
Square feetSquare meters0.092903
AcresHectares0.404686
Miles per hourKilometers per hour1.609344

Metric vs US customary units

The metric system is built on powers of 10: 1,000 meters in a kilometer, 100 centimeters in a meter. US customary units grew from older English measures, so the steps are irregular: 12 inches in a foot, 3 feet in a yard and 5,280 feet in a mile. Since 1959 US units have been officially defined in metric terms, which is why conversions like 1 inch = 2.54 cm are exact.

Temperature is different

Most units convert by multiplying, but temperature scales have different zero points. That is why 0 °C equals 32 °F rather than 0 °F. Kelvin starts at absolute zero (−273.15 °C), and one kelvin step is the same size as one degree Celsius.

Measuring a room or yard? Try the square footage calculator or the volume calculator.

Last reviewed October 2026.

Frequently asked questions

How many units can I convert between?

This converter covers 7 types of measurement (length, weight, volume, temperature, area, speed, digital storage) and 54 units in total, including both US customary and metric units.

Are US and UK gallons the same?

No. A US gallon is 3.785 liters, while an imperial (UK) gallon is 4.546 liters. The volume units in this converter, such as cups, pints, quarts and gallons, are US customary units.

Why does a 1 TB drive show less space on my computer?

Drive makers use decimal units, where 1 terabyte is 1,000,000,000,000 bytes. Many operating systems count in binary units (1 TiB = 1,099,511,627,776 bytes) but still label them TB, so a 1 TB drive shows about 931 GB. Pick the "1024" units here to match your computer.

How do I convert Celsius to Fahrenheit by hand?

Multiply by 9, divide by 5, then add 32. For example, 20 °C × 9 ÷ 5 + 32 = 68 °F. To go back, subtract 32, multiply by 5 and divide by 9.

How accurate are the conversions?

The converter uses exact international definitions, such as 1 inch = 2.54 cm and 1 pound = 0.45359237 kg. Results are shown with up to 8 significant digits.