Length Converter
Convert between inches, centimetres, feet, metres, miles and kilometres.
Convert from:
| Unit | Amount |
|---|---|
| Inches | — in |
| Centimetres | — cm |
| Feet | — ft |
| Metres | — m |
| Miles | — mi |
| Kilometres | — km |
Length conversion matters most where metric and imperial systems meet — in construction, sport, travel, and international trade. The metric system covers most of the world, but inches, feet, and miles remain the everyday standard in the United States and, for road distances, the United Kingdom.
Quick reference
- 1 inch = 2.54 cm (exactly)
- 1 foot = 30.48 cm = 12 inches
- 1 metre = 3.281 feet ≈ 39.37 inches
- 1 mile = 1.609 km = 5,280 feet
- 1 km = 0.6214 miles ≈ 3,281 feet
- 1 nautical mile = 1.852 km
- Quick mental check: 5 miles ≈ 8 km (actual ratio is 1:1.609)
Real-world distances
| Distance | Metric | Imperial |
|---|---|---|
| Marathon | 42.195 km | 26.2 miles |
| Half marathon | 21.1 km | 13.1 miles |
| 1 mile | 1.609 km | 5,280 ft |
| 1 nautical mile | 1.852 km | — |
| Football pitch (length) | 100–110 m | 109–120 yd |
| Standard athletics track | 400 m | 437 yd |
When do you need this?
- Reading US product dimensions (screens, furniture, lumber) listed in inches or feet
- Following a running plan that mixes miles and kilometres
- Checking room or plot sizes on international property listings
- Converting a recipe that specifies dough thickness in inches
- Working out how far a nautical mile is in land kilometres
- Comparing your height in cm against a chart that shows feet and inches
Understanding the units
Inch
The inch (in) is the base small unit of the imperial system, originally derived from the width of a human thumb. It is used extensively in the United States and United Kingdom for everyday measurements — screen sizes, paper, pipe diameters, and tyre widths all commonly use inches.
Centimetre
One hundredth of a metre. The centimetre (cm) is the standard small unit across metric countries and is used in medicine, engineering, and clothing. It maps cleanly to inches: 2.54 cm = 1 inch exactly, by international definition since 1959.
Foot
Twelve inches make one foot (ft). It remains the standard unit for height in the United States and is widely used in aviation — altitude is still measured in feet internationally, regardless of which measurement system a country otherwise uses.
Metre
The metre (m) is the SI base unit of length, defined since 1983 as the distance light travels in a vacuum in 1/299,792,458 of a second. It is the everyday unit of room size, athletics track lengths, and most engineering work outside the US.
Mile
One mile equals exactly 1,609.344 metres. Road signs in the US, UK, and Liberia show distances in miles. The unit traces back to the Roman mille passuum — a thousand paces.
Kilometre
One thousand metres. The kilometre (km) is the standard unit for road distances in most of the world. It is also commonly used in weather reports (visibility), running events, and cycling.
Common mistakes
- Confusing feet with metres when reading property listings — 1,000 sq ft is only about 93 m², a big difference
- Using 1.6 as the miles-to-km conversion instead of 1.609 — adds up over long distances
- Mixing up a nautical mile (1.852 km) with a statute mile (1.609 km) in navigation contexts
- Converting a height like 5′11″ by treating 5.11 as a decimal — the correct conversion is (5 × 30.48) + (11 × 2.54) = 180.34 cm
- Assuming UK road signs show kilometres — they still use miles
Which should you use?
For global communication — use metric (metres, kilometres). It's the international standard in science, medicine, and most industries.
For US audiences — use feet, inches, and miles. Construction, real estate, and consumer products in the US are still overwhelmingly imperial.
For aviation — altitude uses feet universally. Horizontal distances in aviation use nautical miles.
For running — decide based on your event. Road races in the US often use miles; most international races use kilometres.
Frequently asked questions
How many cm in an inch?
There are exactly 2.54 centimetres in one inch. This has been the international standard since 1959. To convert inches to cm, multiply by 2.54. To go the other way, divide by 2.54.
How many feet in a metre?
One metre is approximately 3.281 feet. To convert metres to feet, multiply by 3.281. To convert feet to metres, multiply by 0.3048. The exact value is 1 foot = 0.3048 m.
How many kilometres in a mile?
One mile equals exactly 1.60934 kilometres. To convert miles to km, multiply by 1.609. To convert km to miles, multiply by 0.6214. A quick mental shortcut: 5 miles ≈ 8 km.
How do I convert 5 feet 11 inches to centimetres?
Convert each part separately, then add. 5 feet × 30.48 = 152.4 cm; 11 inches × 2.54 = 27.94 cm. Total: 180.34 cm. Never treat a height like 5′11″ as the decimal 5.11 before converting — that gives a wrong result.
How many inches in a foot?
There are exactly 12 inches in one foot, and 3 feet in one yard. One yard equals 36 inches or 91.44 centimetres.
How many countries still use miles instead of kilometres?
Only three countries primarily use miles for road distances: the United States, the United Kingdom, and Liberia. The rest of the world uses kilometres. The UK uses metric for most purposes but keeps miles for road signs.
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