Metric to imperial conversions

The conversions people need most are: 1 inch = 2.54 cm exactly, 1 kg ≈ 2.205 lb, 1 mile ≈ 1.609 km, 1 US gallon ≈ 3.785 litres, and °F = °C × 9/5 + 32. The chart below lists the rest, with quick rules for doing them in your head. For an exact answer, type the value into the free unit converter, which uses the official defined factors for length, weight, temperature, volume, area, speed, time and data size.

Most of the world uses the metric system. The US uses US customary units for everyday life, and the UK still uses miles, pints and stones alongside metric. So recipes, height and weight, road signs and product labels often need converting.

Length

From	To	Multiply by	Example
Centimetres	Inches	÷ 2.54	180 cm = 70.87 in
Inches	Centimetres	× 2.54	12 in = 30.48 cm
Metres	Feet	× 3.2808	2 m = 6.56 ft
Feet	Metres	× 0.3048	6 ft = 1.83 m
Metres	Yards	× 1.0936	100 m = 109.36 yd
Kilometres	Miles	× 0.62137	10 km = 6.21 mi
Miles	Kilometres	× 1.609344	26.2 mi = 42.16 km

The inch, foot, yard and mile are all defined exactly in metres (1 inch = 25.4 mm), so these conversions are exact, not estimates.

Height in feet and inches: the converter takes one unit at a time, so convert to inches first. 5 ft 10 in is 5 × 12 + 10 = 70 inches, and 70 inches is 177.8 cm. Going the other way, 180 cm is 70.87 inches, which is 5 feet (60 inches) with 10.87 inches left, so about 5 ft 11 in. A full chart is in height in feet and inches to cm.

Weight (mass)

From	To	Multiply by	Example
Kilograms	Pounds	× 2.20462	70 kg = 154.32 lb
Pounds	Kilograms	× 0.45359237	150 lb = 68.04 kg
Grams	Ounces	÷ 28.3495	100 g = 3.53 oz
Ounces	Grams	× 28.3495	8 oz = 226.8 g
Kilograms	Stone	÷ 6.35029	70 kg = 11.02 st

The UK often gives body weight in stone and pounds (1 stone = 14 lb). 70 kg is about 11 stone 0.3 lb, or 11 st 0 lb in everyday terms. For body weight and BMI, there's also a guide on calculating your BMI in metric or imperial.

Tons are a trap: a US ton is 2,000 lb (907.18 kg), a UK ton is 2,240 lb (1,016.05 kg), and a metric tonne is 1,000 kg. The converter lists all three.

Temperature

Temperature uses a formula, not a single factor:

• °C to °F: multiply by 9/5 (1.8), then add 32.
• °F to °C: subtract 32, then multiply by 5/9.

Celsius	Fahrenheit	What it is
−40 °C	−40 °F	Where the two scales meet
0 °C	32 °F	Water freezes
20 °C	68 °F	Room temperature
25 °C	77 °F	A warm day
37 °C	98.6 °F	Typical body temperature
100 °C	212 °F	Water boils at sea level
180 °C	356 °F	Common oven setting

Quick mental rule: double the Celsius and add 30. 20 °C gives 70 °F (the exact answer is 68). It's close enough for weather, not for cooking or medicine.

Volume

From	To	Multiply by	Example
Litres	US gallons	× 0.264172	50 L = 13.21 US gal
US gallons	Litres	× 3.785411784	1 US gal = 3.785 L
UK gallons	Litres	× 4.54609	1 UK gal = 4.546 L
US cups	Millilitres	× 236.588	1 cup = 236.6 ml
US tablespoons	Millilitres	× 14.787	1 tbsp = 14.8 ml
US teaspoons	Millilitres	× 4.929	1 tsp = 4.9 ml
US fluid ounces	Millilitres	× 29.574	12 fl oz = 354.9 ml
UK pints	Millilitres	× 568.26	1 pint = 568 ml

US and UK units share names but not sizes. A UK (imperial) gallon is about 20% bigger than a US gallon, and a UK pint is 568 ml against 473 ml for a US pint. The converter lists US and UK versions separately, so pick the one your recipe or label uses.

Area and speed

From	To	Multiply by	Example
Square metres	Square feet	× 10.7639	50 m² = 538.2 ft²
Square feet	Square metres	× 0.092903	1,000 ft² = 92.9 m²
Hectares	Acres	× 2.47105	2 ha = 4.94 acres
Acres	Square metres	× 4,046.86	1 acre = 4,046.9 m²
km/h	mph	× 0.62137	100 km/h = 62.1 mph
mph	km/h	× 1.609344	60 mph = 96.6 km/h

Flat and house sizes in India are usually quoted in square feet, while plans and much of the world use square metres, so the area conversion comes up a lot when comparing property.

Data size: MB vs MiB

The converter also handles data. A megabyte (MB) is 1,000,000 bytes, and a mebibyte (MiB) is 1,048,576 bytes. That's why a 500 GB drive shows up as about 465.66 GiB on some computers: nothing is missing, the units are different. The full story is in KB vs KiB and MB vs MiB.

Using the converter

Open the free unit converter:

1. Pick what you're converting: Length, Weight, Temperature, Volume, Area, Speed, Time or Data size.
2. Type a number in Value. Decimals and grouped numbers like 1,250 work.
3. Choose the From and To units. Press Swap to flip them.
4. Read the result and press Copy result.

Results update as you type and are shown to up to 10 decimal places, so you can round them as much as your task needs.

Convert yours now

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