Miles to Kilometers Converter

1 mile equals exactly 1.609344 kilometers. The figure is fixed, not rounded: the 1959 international yard and pound agreement defined the yard as exactly 0.9144 meters, which makes the statute mile (1,760 yards) exactly 1,609.344 meters. The US, UK, Canada, Australia, New Zealand, and South Africa all adopted that definition together, so every modern conversion table uses the same value.

The mile traces back to the Roman mille passus (a thousand paces) and entered English law as the 5,280-foot statute mile. The US inherited the unit and retained it after the 1975 Metric Conversion Act made metric adoption voluntary. Miles remain prominent on roads in the US and UK, while most countries use kilometers.

25 mph = 40 km/h (school zones), 35 mph = 56 km/h (residential), 45 mph = 72 km/h (urban arterials), 55 mph = 88 km/h (older interstate limit, still common in rural states), 65 mph = 105 km/h (most interstates), 70 mph = 113 km/h (rural interstates), and 75 mph = 121 km/h (parts of Texas, Utah, Wyoming). Exact factor: multiply mph by 1.609344 for km/h, or by 1.6 for a close mental estimate.

Multiply miles by 1.6 (or by 8/5) for a quick estimate. So 10 mi is roughly 16 km (exact: 16.09 km), 50 mi is about 80 km (exact: 80.47 km), and 100 mi is about 160 km (exact: 160.93 km). The shortcut undercounts by about 0.6 percent, which is close enough for driving distance and travel planning. For km to miles, divide by 1.6, or for higher accuracy multiply km by 0.6214.

A 5K race equals about 3.11 miles (3.10686), a 10K is 6.21 miles (6.21371), and a half marathon is 13.11 miles or exactly 21.0975 km. The official IAAF marathon distance is 42.195 km, which works out to 26.2188 miles, written colloquially as 26.2. The mile mark in a marathon (mile 1, mile 13, mile 26) is the standard landmark for US races, while metric races and international events use kilometer markers (5K, 10K, half-marathon split, 30K, 40K).