π Length Converter
Convert between metric and imperial lengths, with runner presets.
Converted Length
How to Use This Converter
Enter a length, pick the from and to units, and the converter shows the result plus the value in every other unit. Runner presets jump straight to common race distances.
Enter the length value. Negatives are allowed for temperature-style offsets like elevation change.
Choose the from and to units: mm, cm, m, km, inches, feet, yards, miles, or nautical miles.
Use presets for 5K, 10K, half marathon, marathon, or a 5'9" height conversion.
Scan the full table for the unit you actually need.
Exact Conversion Factors
Since 1959 the inch has been defined as exactly 2.54 centimeters, so inch-to-metric conversions are exact, not approximate. The mile (1,609.344 m) and yard (0.9144 m) derive from it. Going the other way produces repeating decimals, which is why 1 km = 0.621371 miles is rounded. For everyday use, the approximations 1 mile β 1.6 km, 1 km β 0.62 miles, 1 m β 3.28 ft, and 1 inch β 2.5 cm are plenty.
Worked Example
Marathon: 42.195 km to miles. 42.195 x 0.621371 = 26.2188 miles, the famous 26.2. A 5K: 5 x 0.621371 = 3.1069 miles. Height 5'9" = 69 inches: 69 x 2.54 = 175.26 cm. And 100 meters, the sprint distance: 100 / 0.9144 = 109.361 yards, just over a football field.
Where This Comes Up
Runners live in both systems: training plans in miles, race bibs in kilometers. Travelers convert road distances and hiking trail lengths. Home projects bounce between feet and meters for room dimensions, and fabric or DIY work needs inches to centimeters. The nautical mile belongs to aviation and sailing, where one minute of latitude equals one nautical mile and chart math stays simple.
Frequently Asked Questions
How many feet are in a mile?
5,280 feet. It comes from the old English furlong: 8 furlongs of 660 feet each. In metric that is 1,609.344 meters, or 1.609344 kilometers.
How many kilometers is a marathon?
42.195 kilometers, which is 26.219 miles. The distance was standardized for the 1908 London Olympics so the race could finish in front of the royal box. A half marathon is 21.0975 km (13.109 miles), a 10K is 10 km (6.214 miles), and a 5K is 5 km (3.107 miles).
What is the easiest way to convert inches to cm?
Multiply inches by 2.54. The inch is defined as exactly 2.54 centimeters, so the conversion is exact, not approximate. For a quick estimate, multiply by 2.5 and add a little.
What is the difference between a nautical mile and a regular mile?
A nautical mile is 1,852 meters (about 1.151 statute miles), defined as one minute of latitude. Pilots and sailors use it because it ties directly to charts. A statute (regular) mile is 1,609.344 meters.
How do I convert my height to centimeters?
Multiply feet by 30.48 and add inches times 2.54. At 5'9" (69 inches): 69 x 2.54 = 175.26 cm, usually rounded to 175 cm. Use the height preset in this converter to skip the math.