About Length Converter
This length converter changes a measurement between ten units: millimetres, centimetres, metres, kilometres, micrometres, inches, feet, yards, miles and nautical miles. The factors are exact by definition, not rounded: an inch is 2.54 cm, a foot is 0.3048 m, a yard is 0.9144 m and a mile is 1.609344 km. In the other direction a metre is 3.28084 feet and a kilometre is 0.621371 miles. The result is shown to six decimal places with the factor for your pair, and a table underneath lists the same distance in every unit. It takes one number in one unit, so a height such as 5 ft 7 in needs to be entered as 67 inches.
Length conversion chart: one of each unit
Each row is the tool's output for a Value of 1 in that unit.
| 1 unit | Millimetres | Metres | Inches | Feet | Yards |
|---|---|---|---|---|---|
| 1 micrometre (µm) | 0.001 | 0.000001 | 0.000039 | 0.000003 | 0.000001 |
| 1 millimetre | 1 | 0.001 | 0.03937 | 0.003281 | 0.001094 |
| 1 centimetre | 10 | 0.01 | 0.393701 | 0.032808 | 0.010936 |
| 1 inch | 25.4 | 0.0254 | 1 | 0.083333 | 0.027778 |
| 1 foot | 304.8 | 0.3048 | 12 | 1 | 0.333333 |
| 1 yard | 914.4 | 0.9144 | 36 | 3 | 1 |
| 1 metre | 1,000 | 1 | 39.370079 | 3.28084 | 1.093613 |
| 1 kilometre | 1,000,000 | 1,000 | 39,370.07874 | 3,280.839895 | 1,093.613298 |
| 1 mile | 1,609,344 | 1,609.344 | 63,360 | 5,280 | 1,760 |
| 1 nautical mile | 1,852,000 | 1,852 | 72,913.385827 | 6,076.115486 | 2,025.371829 |
Thousands separators are added for reading; the Result line prints plain digits.
Miles to km and km to miles for road and race distances
| Miles | Kilometres | Kilometres | Miles |
|---|---|---|---|
| 0.5 | 0.804672 | 1 | 0.621371 |
| 1 | 1.609344 | 5 (a 5K) | 3.106856 |
| 3 | 4.828032 | 8 | 4.97097 |
| 5 | 8.04672 | 10 (a 10K) | 6.213712 |
| 10 | 16.09344 | 21.0975 (half marathon) | 13.109379 |
| 13.1 | 21.082406 | 30 | 18.641136 |
| 26.2 | 42.164813 | 42.195 (marathon) | 26.218757 |
| 30 | 48.28032 | 50 | 31.06856 |
| 50 | 80.4672 | 80 | 49.709695 |
| 60 | 96.56064 | 100 | 62.137119 |
| 70 | 112.65408 | 120 | 74.564543 |
| 100 | 160.9344 | 160.934 | 99.999751 |
The left pair and right pair are separate conversions. The same factors convert speed limits: 30, 50, 60 and 70 mph are about 48, 80, 97 and 113 km/h.
Height conversion: centimetres to inches and feet
The tool gives feet as a decimal. The last column splits the inches figure into feet and inches by hand.
| Centimetres | Inches | Decimal feet | Feet and inches |
|---|---|---|---|
| 150 cm | 59.055118 in | 4.92126 ft | 4 ft 11.1 in |
| 160 cm | 62.992126 in | 5.249344 ft | 5 ft 3.0 in |
| 165 cm | 64.96063 in | 5.413386 ft | 5 ft 5.0 in |
| 170 cm | 66.929134 in | 5.577428 ft | 5 ft 6.9 in |
| 175 cm | 68.897638 in | 5.74147 ft | 5 ft 8.9 in |
| 180 cm | 70.866142 in | 5.905512 ft | 5 ft 10.9 in |
| 185 cm | 72.834646 in | 6.069554 ft | 6 ft 0.8 in |
| 190 cm | 74.80315 in | 6.233596 ft | 6 ft 2.8 in |
Decimal feet are not feet and inches: 5.577428 ft is 5 ft 6.9 in, not 5 ft 5.8 in. To split it yourself, convert to inches, take off 12 for each whole foot and keep the remainder.
Distance converter for UK units: yards and miles to metres
UK road signs give distances in miles and yards, while maps, athletics and most of Europe use metres and kilometres.
| Imperial distance | Metres | Also equal to |
|---|---|---|
| 50 yards | 45.72 m | 150 feet |
| 100 yards | 91.44 m | 300 feet |
| 200 yards | 182.88 m | 600 feet |
| 300 yards | 274.32 m | 900 feet |
| 440 yards (quarter mile) | 402.336 m | 1,320 feet |
| 880 yards (half mile) | 804.672 m | 2,640 feet |
| 1,000 yards | 914.4 m | 0.568182 miles |
| 1,760 yards (1 mile) | 1,609.344 m | 5,280 feet |
Going the other way, 100 m is 109.36133 yards, 400 m is 437.445319 yards and 1,500 m is 1,640.419948 yards.
Worked length conversions
A height given in feet and inches
5 ft 7 in is 67 inches. Value 67, From Inch (in), To Centimetre (cm)
170.18 cm
The table underneath shows the same height as 1.7018 m and 5.583333 ft.
A ceiling height on a US plan
8 ft 6 in is 102 inches. Value 102, From Inch (in), To Metre (m)
2.5908 m
A marathon in miles
Value 42.195, From Kilometre (km), To Mile (mi)
26.218757 mi
The Rounded line gives the familiar 26.22 mi.
A sea distance
Value 200, From Nautical mile (nmi), To Kilometre (km)
370.4 km
One nautical mile is 1.852 km, so the conversion is exact.
A fraction of an inch in millimetres
Three quarters of an inch is 0.75. Value 0.75, From Inch (in), To Millimetre (mm)
19.05 mm
Enter fractions as decimals: 1/8 is 0.125, 1/4 is 0.25, 1/2 is 0.5.
A 3D-printing layer height in microns
Value 0.2, From Millimetre (mm), To Micrometre (µm)
200 µm
A micron is another name for the micrometre: one thousandth of a millimetre.
Why these conversion factors are exact
Imperial lengths are defined in terms of the metre, so nothing here is an approximation. Under the International Yard and Pound Agreement of 1959, the yard was fixed at exactly 0.9144 metres. Everything else follows: a foot is a third of a yard, so 0.3048 m; an inch is a thirty-sixth, so 25.4 mm; a mile is 1,760 yards, so 1,609.344 m.
The nautical mile belongs to a different family. It was originally one minute of arc of latitude and was standardised internationally in 1929 at exactly 1,852 metres. It remains the unit for sea and air navigation, and one nautical mile per hour is a knot.
Metric units differ only by powers of ten: 10 mm to a centimetre, 100 cm to a metre, 1,000 m to a kilometre, and 1,000 micrometres to a millimetre.
One caution: length factors must not be reused for area or volume. A metre is 3.28084 feet, but a square metre is 10.76391 square feet, because the factor is applied once for each dimension.
Limits to be aware of
- One number, one unit. Compound entries such as 5 ft 7 in or 1 mile 300 yards must be turned into a single unit first.
- Feet are returned as decimals, not as feet and inches, and inches are not shown as fractions such as 3/8.
- The units stop at the nautical mile. Furlongs, chains, fathoms, leagues, astronomical units and light years are not included.
- The foot is the international foot of 0.3048 m. The US survey foot, about 2 parts in a million longer, is not offered.
- Results have six decimal places; anything below 0.000001 appears in scientific notation, for example 1 mm in miles is 6.213712e-7 mi.
How to get your result
- 1
Type the measurement into the Value box.
- 2
Set From to the unit it is in, for example Mile (mi).
- 3
Set To to the unit you want, for example Kilometre (km).
- 4
Read the Result, and the Formula line for the length of one source unit in the target unit.
- 5
Look at the Same value in every unit table when you need the figure in several units, such as both metres and yards.