Unit Converter — Length, Weight, Temperature, Volume & More
Convert between every common unit — metric and imperial, cooking, data, pressure, energy, speed, fuel economy — instantly, in your browser.
1 in = 2.54 cm. Type with the keyboard or numpad; Enter swaps the units.
1 in in every length unit
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This free unit converter handles the conversions people actually search for — inches to centimetres, pounds to kilograms, Fahrenheit to Celsius, miles to kilometres, cups to millilitres, gigabytes to megabytes — and the ones they rarely find in one place: pressure, energy, power, angles, fuel economy, data transfer rates. Pick a category, type a number, and every other unit in that category is shown at once.
The conversion factors are the defined values where a definition exists (an inch is exactly 0.0254 metres; a pound is exactly 0.45359237 kilograms; a US gallon is exactly 3.785411784 litres) and the standard reference values otherwise. Temperature and fuel economy are not simple multiplications and are handled properly: 0 °C is 32 °F, and 30 mpg is 7.84 L/100 km. Everything runs in your browser.
How to use
- Choose a category — Length, Weight, Temperature, Volume, Area, Speed, Time, Data, Data rate, Pressure, Energy, Power, Angle, Fuel economy, Frequency or Force.
- Type a value in the From box and pick its unit. The To box updates instantly; use the ⇄ button (or press Enter) to swap direction.
- Below the converter, the value is shown in every unit of the category. Click any row to make it the target unit.
- On a phone the numeric keypad opens automatically; on a desktop, type and use the numpad as you would in a spreadsheet.
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54. The inch has been defined as 25.4 millimetres by international agreement since 1959, so the conversion is exact rather than approximate: multiply inches by 2.54 to get centimetres, and divide centimetres by 2.54 to get inches.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9. So 68 °F is (68 − 32) × 5/9 = 20 °C. To go the other way, multiply by 9/5 and add 32. Temperature is the one common conversion that is not a simple factor, because the scales start at different points — which is why this tool handles it separately.
What is the difference between a KB and a KiB, or a GB and a GiB?
KB, MB and GB use powers of 1000 (1 GB = 1,000,000,000 bytes) — the standard used by drive manufacturers and the SI system. KiB, MiB and GiB use powers of 1024 (1 GiB = 1,073,741,824 bytes) — what operating systems traditionally report. The gap is why a '1 TB' drive shows as about 931 GiB. Both are available here.
Which gallon and pint does the converter use?
Both. US customary units (US gallon = 3.785 L, US pint = 473 mL, US fluid ounce = 29.57 mL) and imperial UK units (UK gallon = 4.546 L, UK pint = 568 mL, UK fluid ounce = 28.41 mL) are listed separately, because a UK pint is 20% larger than a US pint and mixing them up is the most common volume mistake.
How is fuel economy converted between mpg and L/100 km?
They are reciprocals, not multiples: mpg measures distance per fuel, L/100 km measures fuel per distance. The formula is L/100 km = 235.21 ÷ mpg (US gallons) or 282.48 ÷ mpg (UK gallons). So 30 US mpg ≈ 7.84 L/100 km and 40 UK mpg ≈ 7.06 L/100 km.
Is my data sent anywhere?
No. All conversions are computed in your browser. There is no account, no upload and nothing to install.
The conversions people search for most
• Length: 1 inch = 2.54 cm · 1 foot = 30.48 cm · 1 mile = 1.609 km · 1 metre = 3.281 feet.
• Weight: 1 kg = 2.2046 lb · 1 lb = 453.6 g · 1 stone = 6.35 kg · 1 oz = 28.35 g.
• Temperature: 0 °C = 32 °F · 100 °C = 212 °F · 37 °C = 98.6 °F · −40 is the same on both scales.
• Volume (cooking): 1 US cup = 236.6 mL · 1 tbsp = 14.79 mL · 1 tsp = 4.93 mL · 1 US fl oz = 29.57 mL.
• Speed: 100 km/h = 62.14 mph · 1 knot = 1.852 km/h.
• Data: 1 GB = 1000 MB · 1 GiB = 1024 MiB · 8 bits = 1 byte · 100 Mbps = 12.5 MB/s.
Why some conversions are exact and others are not
Most imperial-to-metric factors are exact by definition. In 1959 the inch, foot, yard, mile and pound were all redefined in terms of metric units, so 1 inch = 0.0254 m and 1 lb = 0.45359237 kg with no rounding. The US gallon (231 cubic inches) and UK gallon (4.54609 L) are also exact.
Energy and power factors are defined by convention rather than physics: a calorie is 4.184 J by definition, a BTU is usually taken as 1055.056 J, and mechanical horsepower is 745.7 W. This converter uses those standard values, which are the ones in engineering references and government tables.
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