About Length Conversion
Length is one of the most commonly converted measurements. Whether you're working on a construction project, following an international recipe, or reading scientific data, converting between metric and imperial length units is essential. Our calculator uses official conversion factors for maximum accuracy.
How length conversion works
Every unit in this converter is defined as an exact number of meters. Since the international yard and pound agreement of 1959, one inch is exactly 2.54 centimeters, which fixes the rest of the US customary system: a foot is 0.3048 m, a yard is 0.9144 m and a mile is 1,609.344 m.
To convert, multiply by the first unit's length in meters and divide by the second unit's. The converter does this in one step, so feet to inches, miles to kilometers and millimeters to yards all use the same exact factors.
Worked example: height in feet and inches
To turn 5 ft 10 in into centimeters, first make it all inches: 5 × 12 + 10 = 70 in. Then multiply by 2.54: 70 × 2.54 = 177.8 cm. Going the other way, divide centimeters by 2.54 to get inches, then divide by 12 for feet.
Quick estimates
These rounded figures are close enough for everyday use:
- 1 meter is about 3.28 feet, or 39.37 inches
- 1 foot is about 30.5 centimeters
- 1 kilometer is about 0.62 miles, so 10 km is about 6.2 miles
- 1 mile is about 1.61 kilometers
- 1 inch is exactly 25.4 millimeters
Units that look alike but differ
A nautical mile is 1,852 meters, about 15% longer than a statute mile, and it is used at sea and in aviation. Older US land records may use the US survey foot, which is about 2 parts per million longer than the international foot. NIST retired it at the end of 2022, and this converter uses the international foot.