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To convert kilometers to miles, multiply by 0.621371. So 10 km = 6.214 miles, 42.195 km (marathon distance) = 26.219 miles, and 100 km = 62.137 miles. A useful mental shortcut: multiply km by 0.6 for a rough estimate — it's about 3% low but close enough for casual use.
The marathon is 42.195 km — famously described as 26.2 miles — illustrating how the same distance has different intuitive meanings across systems. European road signs show km, UK and US signs show miles. Runners choosing a GPS watch must understand which unit their training data uses.
Did you know? "Kilometer" literally means 1,000 meters (kilo = 1,000 in Greek). The kilometer became a standard international road measurement unit in the early 20th century. Only the UK, US, and a few other nations still use miles as the primary road distance unit.
Road trips in the UK and USA require miles, while navigation apps in Europe use kilometers. Running and cycling apps let users choose units, but race distances are internationally described in kilometers — knowing the mile equivalent helps American athletes set pace goals.