Convert between metric and imperial length units instantly — millimeters, centimeters, meters, kilometers, inches, feet, yards, miles and nautical miles. Enter a value, choose your starting unit, and pick what you want to convert it to.
Quick reference
- 1 inch = 2.54 cm (exact)
- 1 foot = 30.48 cm
- 1 yard = 0.9144 m
- 1 mile = 1.609344 km
- 1 nautical mile = 1.852 km
- 1 cm = 0.393701 in
- 1 m = 3.28084 ft
- 1 km = 0.621371 mi
Length conversions come up constantly: following a recipe written in imperial units, checking a product’s dimensions before buying, or converting a road sign distance. The table below covers the conversions people look up most often.
How to convert length units
Every length unit is a fixed multiple of the meter, so any conversion works the same way: convert to meters, then to the unit you want. The key definitions are exact: 1 inch = 2.54 cm, 1 foot = 12 inches = 30.48 cm, 1 yard = 3 feet = 0.9144 m and 1 mile = 1,760 yards = 1.609344 km.
Example: to convert a height of 170 cm to feet and inches, divide by 2.54 to get 66.93 inches. Divide by 12 to get 5 feet, with 6.93 inches left over — so 170 cm is about 5 ft 7 in.
Frequently asked questions
How many centimeters are in an inch?
Exactly 2.54. The inch was defined as 2.54 cm by international agreement in 1959, so this conversion is exact rather than an approximation.
How do I convert kilometers to miles?
Multiply kilometers by 0.621371 (or divide by 1.609344). For a quick mental estimate, multiply by 0.6 — so 10 km is roughly 6 miles (6.21 exactly).
Is a nautical mile the same as a mile?
No. A nautical mile is 1,852 meters, while a standard (statute) mile is 1,609.344 meters. Nautical miles are used at sea and in aviation because one nautical mile corresponds to one minute of latitude.