Length Converter
Length converter for metric and imperial distances — millimeters up to miles.
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles and nautical miles in one place. Enter a value, choose the two units and read the result instantly. All factors are the exact internationally agreed values.
Popular Length Conversions
- Centimeter to Inch
- Inch to Centimeter
- Meter to Foot
- Foot to Meter
- Kilometer to Mile
- Mile to Kilometer
- Millimeter to Inch
- Inch to Foot
- Foot to Inch
- Centimeter to Foot
- Meter to Yard
- Foot to Centimeter
All Length Units
| Unit | Symbol | Definition |
|---|---|---|
| Millimeter | mm | One thousandth of a meter, the SI base unit of length. |
| Centimeter | cm | One hundredth of a meter — a common everyday metric unit. |
| Meter | m | The SI base unit of length, originally defined from the Earth's meridian and now fixed by the speed of light. |
| Kilometer | km | One thousand meters. |
| Inch | in | A US customary and imperial unit equal to exactly 25.4 millimeters, with 12 inches to a foot. |
| Foot | ft | A US customary and imperial unit equal to exactly 12 inches or 0.3048 meters. |
| Yard | yd | A US customary and imperial unit equal to 3 feet or 0.9144 meters. |
| Mile | mi | A US customary and imperial unit equal to 5,280 feet or 1,609.344 meters. |
| Nautical Mile | nmi | Defined as exactly 1,852 meters, based on one minute of latitude along a meridian. |
How length conversion works
The metre is the base unit of length. Since 1983 it has been defined as the distance light travels in a vacuum in 1/299,792,458 of a second. Every imperial and US customary length unit is defined from the metre, not the other way round:
1 foot = 12 in = 0.3048 m (exact)
1 yard = 3 ft = 0.9144 m (exact)
1 mile = 5,280 ft = 1,609.344 m (exact)
1 nautical mile = 1,852 m (exact)
To convert, multiply by the factor shown on each unit's row. Inches to centimetres: multiply by 2.54. Centimetres to inches: divide by 2.54. Kilometres to miles: multiply by 0.621371. Feet to metres: multiply by 0.3048.
Height chart: centimetres to feet and inches
| Centimetres | Inches | Feet and inches |
|---|---|---|
| 150 cm | 59.055 in | 4 ft 11.1 in |
| 155 cm | 61.024 in | 5 ft 1 in |
| 160 cm | 62.992 in | 5 ft 3 in |
| 165 cm | 64.961 in | 5 ft 5 in |
| 170 cm | 66.929 in | 5 ft 6.9 in |
| 175 cm | 68.898 in | 5 ft 8.9 in |
| 180 cm | 70.866 in | 5 ft 10.9 in |
| 185 cm | 72.835 in | 6 ft 0.8 in |
| 190 cm | 74.803 in | 6 ft 2.8 in |
So a person who is 170 cm tall is 5 ft 6.9 in. To go the other way, 5 ft 10 in is (5 × 12 + 10) × 2.54 = 177.8 cm.
Distances: kilometres and miles
| Kilometer (km) | Mile (mi) |
|---|---|
| 1 km | 0.621371 mi |
| 5 km | 3.10686 mi |
| 10 km | 6.21371 mi |
| 21.0975 km | 13.1094 mi |
| 42.195 km | 26.2188 mi |
| 100 km | 62.1371 mi |
| 500 km | 310.686 mi |
Mental shortcut: miles ≈ kilometres × 0.6, or multiply by 5 and divide by 8. 100 km is about 62 miles (exact: 62.14).
Where each unit is used
- Millimetres and centimetres: engineering drawings, tailoring, screen and phone dimensions, body measurements.
- Metres and kilometres: building plans, running tracks, road distances and signs in Pakistan and most of the world.
- Inches and feet: screen sizes (TVs, monitors, phones), human height, tyre and pipe sizes, and plot and room dimensions in South Asia and the US.
- Yards and miles: road distances and speed limits in the US and UK; cloth is still sold by the yard in many Pakistani markets.
- Nautical miles: aviation and shipping. One nautical mile was originally one minute of latitude, and a speed of one nautical mile per hour is one knot.
Common mistakes to avoid
- Nautical vs statute mile. A nautical mile (1,852 m) is about 15% longer than a statute mile (1,609.344 m). Never swap them in flight or marine calculations.
- US survey foot. It differs from the international foot by about 2 parts per million, which matters only in large-scale surveying. NIST retired it from 1 January 2023, so use the international foot unless a legacy survey says otherwise.
- Mixing mm and cm. 25 mm is 2.5 cm, not 25 cm. Always write the unit next to the number when marking cuts or ordering materials.
- Rounding too early. Inches to millimetres is exact at 25.4. Do not round to 25 for precision work.
Exact conversion factors
| Unit | Symbol | Exact factor |
|---|---|---|
| Millimeter | mm | 1 mm = 0.001 m |
| Centimeter | cm | 1 cm = 0.01 m |
| Meter | m | 1 m = 1 m |
| Kilometer | km | 1 km = 1000 m |
| Inch | in | 1 in = 0.0254 m |
| Foot | ft | 1 ft = 0.3048 m |
| Yard | yd | 1 yd = 0.9144 m |
| Mile | mi | 1 mi = 1609.344 m |
| Nautical Mile | nmi | 1 nmi = 1852 m |
Sources: BIPM, The International System of Units (SI Brochure); NIST Special Publication 811 and Handbook 44.
Frequently Asked Questions
How many centimetres are in an inch?
1 inch is exactly 2.54 centimetres (25.4 mm). To convert inches to cm, multiply by 2.54.
How many feet are in a metre?
1 metre is 3.28084 feet, or about 3 ft 3.37 in.
How do I convert km to miles?
Multiply kilometres by 0.621371. For example 10 km = 6.2137 miles.
How many cm is 5 feet 7 inches?
5 ft 7 in is 67 inches, which is 170.18 cm.
How many kilometres is a mile?
1 mile is exactly 1.609344 kilometres.
What is the difference between a mile and a nautical mile?
A statute mile is 1,609.344 m. A nautical mile is 1,852 m, defined from one minute of latitude, and is used in aviation and at sea.
How many millimetres are in an inch?
Exactly 25.4 millimetres, fixed by the 1959 international yard and pound agreement.
All Length Conversions
Choose a starting unit to see every conversion available from it.