Length Converter
Convert a length between millimeters, centimeters, meters, kilometers, inches, feet, yards and miles — with the exact conversion factor and a quick reference table.
Conversions use exact defined factors (1 in = 25.4 mm exactly).
Formula and calculation
Worked example
To convert 1 ft to cm: feet go to meters at 0.3048, then meters to centimeters at 100, so the result is 30.48. The factor line reads 1 ft = 30.48 cm.
Exact vs. rounded conversions
Metric–imperial length conversions are exact because the units are defined in terms of each other: since 1959, one inch is exactly 25.4 mm, so a foot is exactly 304.8 mm and a mile exactly 1.609344 km. That means “1 m = 3.28084 ft” is a rounding of a number that has infinitely many digits, not an approximation of the physical world. When a conversion matters (machining, surveying, aviation), use the exact fractions this tool applies rather than memory-rounded values.
What the results mean
- 1 ft =
- Your value converted to the target unit, using exact conversion factors (1 inch is defined as exactly 25.4 mm).
- Conversion factor
- The one-to-one factor for this conversion, so you can repeat the arithmetic by hand: value × factor = result.
- Reverse
- The factor in the opposite direction — handy when you need to convert back later.
Frequently asked questions
How many centimeters are in a foot?
Exactly 30.48 — because a foot is defined as 304.8 mm. Going the other way, one centimeter is 0.0328 feet. The converter shows both directions.
How do I convert miles to kilometers?
Multiply miles by 1.609344: 10 miles is 16.09344 km. The factor is exact because the mile is defined as 1.609344 km in international agreements. For a quick mental estimate, multiply by 1.6 and add half a percent.
What is my height in centimeters?
Multiply your height in inches by 2.54, or convert feet-and-inches directly: 5 ft 9 in is 69 inches, which is 175.26 cm. Use the converter for exact values.
Why does 1 meter show as 3.280839895 feet?
Because 1 ÷ 0.3048 has infinitely many digits — the trailing decimal expansion is the exact value rounded for display, not a different measurement. Four to six significant digits are enough for nearly any practical purpose.