A length converter changes a distance from one unit to another, such as meters to feet or miles to kilometers. Formula: in = cm / 2.54; ft = m / 0.3048. 1 meter is 3.2808 feet, and 1 inch is exactly 2.54 centimeters.
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How to use the length converter
- Enter the value.
- Choose the unit to convert from.
- Choose the unit to convert to.
- Read the converted length.
How the length converter works
The length converter supports 19 units, from nanometers and micrometers to kilometers, miles and nautical miles, plus inches, feet, yards and others. It converts your value to meters using each unit’s defined factor, then from meters to the target unit, and shows up to 12 significant digits. Because the US customary units are defined exactly in terms of the meter, the conversions are exact except for the final rounding.
Exact definitions
Since 1959 the international inch has been exactly 2.54 centimeters. That makes the foot exactly 0.3048 meters, the yard exactly 0.9144 meters, and the mile exactly 1,609.344 meters. The international nautical mile is exactly 1,852 meters. The meter itself is defined by the distance light travels in a vacuum in 1/299,792,458 of a second. NIST publishes these values.
Length converter worked example
To convert 1 meter to feet, divide by 0.3048: 1 ÷ 0.3048 = 3.280839895 feet. A height of 5 feet 10 inches is 70 inches, and 70 × 2.54 = 177.8 centimeters. A 10 km race is 6.2137 miles, and a marathon of 42.195 km is about 26.2188 miles. The length converter gives these instantly.
| Value | To | Result |
|---|---|---|
| 1 m | ft | 3.280839895 |
| 1 in | cm | 2.54 (exact) |
| 1 mi | km | 1.609344 (exact) |
| 5 ft 10 in | cm | 177.8 |
| 10 km | mi | 6.213711922 |
| 42.195 km | mi | 26.218757 |
Feet and inches
Heights and room sizes are often given in feet and inches. Convert to a single unit before using the length converter: multiply feet by 12 and add the inches, then convert the inches. To go back, divide inches by 12; the whole number is feet and the remainder is inches. For example, 180 cm ÷ 2.54 = 70.87 inches, which is 5 feet 10.87 inches.
The US survey foot
Older US land surveys used the US survey foot, defined as 1200/3937 meters, which is about two parts per million longer than the international foot. The difference is about 3.2 millimeters per kilometer. NIST and other agencies retired the survey foot for new work at the end of 2022. For everyday measurements the difference is irrelevant, but it matters in large-scale mapping.
Choosing precision
The converter shows many digits, but your answer is only as precise as your measurement. A tape measure reading to the nearest millimeter does not justify six decimal places in inches. Round the output to match the input; for construction, the nearest sixteenth of an inch or the nearest millimeter is usually enough. Use the length converter’s full precision for engineering calculations, and round only at the end.
Everyday length converter examples
A 55-inch television is measured diagonally and is about 139.7 centimeters. A 6-foot sofa is 182.88 centimeters. A road sign that says 50 miles means about 80.47 kilometers, and a 5 km run is about 3.11 miles. Paper sizes differ by country too: US letter paper is 8.5 by 11 inches, or 215.9 by 279.4 millimeters, while A4 is 210 by 297 millimeters. Each of these takes one step.
Very small and very large lengths
Scientists measure wavelengths of light in nanometers and cells in micrometers; a human hair is roughly 50 to 100 micrometers across. At the other end, nautical miles and kilometers cover travel distances. Choose the unit that keeps the number readable, typically between 0.1 and 1,000.
Tips
- Remember 1 inch = 2.54 cm exactly.
- Convert feet and inches to one unit first.
- Use nautical miles only for marine and air navigation.
- Round to the precision of your measurement.
Related converters and calculators
Related calculators:
- cm to feet: height
- Inches to cm: inches
- Unit converter: all units
- SI prefix converter: prefixes
Sources
NIST: SI units – length; NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically.
Formula and method
Target = value × factor(source) ÷ factor(target); factors are in meters.
Your value is multiplied by the source unit factor and divided by the target unit factor (both expressed in the base unit). Results are shown rounded; the calculation uses full precision.
Questions about this calculator
How many feet in a meter?
About 3.28084.
Is 1 inch exactly 2.54 cm?
Yes, by definition since 1959.
How many km in a mile?
1.609344 exactly.
What is a nautical mile?
Exactly 1,852 meters.
What was the US survey foot?
A slightly longer foot retired for new work after 2022.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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