KMH to MPH conversion

Kilometers per hour to miles per hour

Speed limits, car speedometers and weather reports use km/h in most of the world and mph in the United States and the United Kingdom. Since a mile is 1.609344 km, 1 km/h = 0.621371 mph: divide the km/h figure by 1.609, or multiply it by 0.6214.

Mental shortcut

Take five eighths, or halve the number and add a quarter of it: 100 km/h → 50 + 12.5 = 62.5 mph (62.1 exactly). Drivers who cross borders often memorise a few landmarks: 50 km/h is 31 mph, 80 is 50, 100 is 62, 120 is 75, 130 is 81.

• 30 km/h = 18.6 mph (a school zone)
• 50 km/h = 31.1 mph (a city street)
• 80 km/h = 49.7 mph
• 90 km/h = 55.9 mph
• 100 km/h = 62.1 mph
• 110 km/h = 68.4 mph
• 120 km/h = 74.6 mph
• 130 km/h = 80.8 mph (a French motorway)
• 200 km/h = 124.3 mph
• 300 km/h = 186.4 mph

Renting a car abroad

A rental car in Europe shows km/h; the limits on the signs are also km/h, so no conversion is needed to obey them — but a feel for what the numbers mean in mph helps you judge how fast traffic is moving. The reverse applies to Europeans driving in the US: a 65 mph interstate limit is 105 km/h.

Wind, weather and sport

Wind speeds are reported in km/h in Canada and Australia and in mph in the US. A 100 km/h gust is 62 mph — storm force. Tennis serves are shown in both units on broadcasts: a 200 km/h serve is 124 mph. Cyclists and runners track speed in km/h on metric apps and mph on American ones; a 5:00-per-kilometre running pace is 12 km/h, 7.5 mph.

Knots and meters per second

Sailors and pilots use knots: 1 knot is 1.852 km/h or 1.151 mph. Scientists use meters per second: 1 m/s is 3.6 km/h or 2.24 mph.