Since July 1, 1959, U.S. customary lengths have been defined exactly in metric units: 1 inch = 2.54 centimeters, so 1 foot = 0.3048 m, 1 yard = 0.9144 m and 1 mile = 1,609.344 m. NIST traces this to the 1959 international agreement that shortened the American yard slightly. Because the factors are exact, 6 feet is exactly 1.8288 meters, and a mile is exactly 1.609344 km.
This converter uses those exact definitions, plus the international nautical mile of 1,852 m used at sea and in aviation. Every result is also shown in all the other units.
How to use the length converter
- Enter the length. Decimals are fine; for 5 ft 9 in, enter 5.75 ft or 69 in.
- Choose the unit you have and the unit you want.
- Read the result, the one-unit factor and the table of equivalents.
Formula
Every unit is converted to meters first and then to the target unit, so any pair works with the same exact factors.
Worked example
Convert 6 feet to meters, and 10 km to miles.
- 6 ft × 0.3048 m/ft = 1.8288 m.
- 10 km = 10,000 m; 10,000 ÷ 1,609.344 = 6.2137 mi.
- A 5 ft 9 in person: 69 in × 2.54 = 175.26 cm.
Common length conversions
| From | To | Multiply by |
|---|---|---|
| inches | centimeters | 2.54 (exact) |
| centimeters | inches | 0.393701 |
| feet | meters | 0.3048 (exact) |
| meters | feet | 3.28084 |
| yards | meters | 0.9144 (exact) |
| miles | kilometers | 1.609344 (exact) |
| kilometers | miles | 0.621371 |
| nautical miles | kilometers | 1.852 (exact) |
The U.S. survey foot (1200/3937 m, about 0.3048006 m) was used for some land surveying and has been phased out in favor of the international foot; this converter uses the international foot. For areas and volumes, use the area converter and volume converter. For running distances, the pace calculator converts per-km and per-mile paces.
Height in feet and inches
Heights are usually written in feet and inches in the U.S. and in centimeters elsewhere. To convert, first turn the height into inches (feet × 12 + inches), then multiply by 2.54:
| Height | Inches | Centimeters |
|---|---|---|
| 5 ft 0 in | 60 | 152.4 |
| 5 ft 4 in | 64 | 162.6 |
| 5 ft 8 in | 68 | 172.7 |
| 6 ft 0 in | 72 | 182.9 |
| 6 ft 4 in | 76 | 193.0 |
Going from centimeters to feet and inches: divide by 2.54 for inches, then divide by 12; the whole number is feet and the remainder is inches. 170 cm = 66.93 in = 5 ft 6.9 in.
Mental shortcuts
- 1 meter is a little more than a yard (about 1.09 yd, or 39.37 in).
- 1 kilometer is about 0.6 mile; a 5K run is 3.1 miles and a 10K is 6.2 miles.
- 1 inch is about 2.5 cm; 1 foot is about 30 cm.
Shortcuts are fine for estimates; use the exact factors for building, sewing or engineering. For running distances and paces, try the pace calculator.
Caveats and assumptions
- Display is limited to 10 significant digits; the underlying factors are exact.
- Uses the international foot and mile, not the retired U.S. survey foot.
Frequently asked questions
How many centimeters are in an inch?
Exactly 2.54 centimeters, by the 1959 international definition.
How many feet are in a meter?
About 3.28084 feet. One foot is exactly 0.3048 m.
How many kilometers are in a mile?
Exactly 1.609344 km. One kilometer is about 0.621371 miles.
What is 6 feet in meters?
1.8288 meters.
What is a nautical mile?
Exactly 1,852 meters (about 1.15078 statute miles). It is used in navigation, and speed in nautical miles per hour is a knot.
How many inches are in a meter?
About 39.37 inches.
How many miles is a 5K?
About 3.107 miles (5 ÷ 1.609344).
How many feet are in a mile?
5,280 feet (1,760 yards).
How many centimeters are in a foot?
Exactly 30.48 centimeters.
How many meters is 100 yards?
91.44 meters.
Sources
- NIST — SI Units: Length (incl. the 1959 redefinition of the inch) — 1 in = 25.4 mm exactly; metric length units
- NIST SP 811 Appendix B.9 — Conversion factors — foot, yard, mile and survey-foot factors
- NIST — Unit Conversion — conversion resources
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.