Length Converter
Convert between metric and imperial lengths — millimeters to miles, feet to meters, inches to centimeters — using the exact international definitions of the inch (25.4 mm) and the mile (1,609.344 m). Results update as you type; exact factors shown.
One mile is 1.6093 kilometers — see the exact factor, not a rounded rule of thumb.
How the length converter works
Every length is converted through the meter, the SI base unit of length. The inch has been defined as exactly 25.4 mm since the 1959 international yard and pound agreement, so a foot is exactly 0.3048 m, a yard 0.9144 m and a statute mile 1,609.344 m. The nautical mile is 1,852 m by international definition.
The US uses customary units (US gallon, short ton, °F) in daily life; NIST SP 811 gives the exact SI factors.
Common length conversions
| From | To | Units |
|---|---|---|
| 1 km | 0.6214 mi | kilometer to miles |
| 1 mi | 1.6093 km | mile to kilometers |
| 1 m | 3.2808 ft | meter to feet |
| 1 ft | 0.3048 m | foot to meters |
| 1 in | 2.54 cm | inch to centimeters |
| 1 cm | 0.3937 in | centimeter to inchs |
| 100 m | 109.3613 yd | meters to yards |
| 1 nmi | 1.852 km | nautical mile to kilometers |
| 5 km | 3.1069 mi | kilometers to miles |
| 10 mi | 16.0934 km | miles to kilometers |
Units in this converter and their exact factors
| Unit | Symbol | One unit in meters |
|---|---|---|
| millimeter | mm | 0.001 meter |
| centimeter | cm | 0.01 meter |
| meter | m | 1 meter |
| kilometer | km | 1,000 meter |
| inch | in | 0.0254 meter |
| foot | ft | 0.3048 meter |
| yard | yd | 0.9144 meter |
| mile | mi | 1,609.344 meter |
| nautical mile | nmi | 1,852 meter |
FAQFrequently asked questions about length conversion
How many centimeters are in an inch?
Exactly 2.54 cm. The inch was fixed at 25.4 mm by international agreement in 1959, so the conversion is exact, not approximate.
How many kilometers are in a mile?
One statute mile is exactly 1.609344 km. Five miles are a little over 8 km; ten kilometers are about 6.2 miles.
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 — about 15% longer. Nautical miles are used at sea and in aviation because one equals one minute of latitude.
How many feet are in a meter?
About 3.2808 feet. Exactly, 1 m = 1 / 0.3048 ft = 3.280839895… ft.
Are these conversions exact?
Yes for every imperial unit here: inch, foot, yard and mile are all defined as exact multiples of the meter. Only the displayed rounding is approximate.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Institute of Standards and Technology (NIST) — United States's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.