How to Convert km/h to mph (and mph to km/h)

Renting a car abroad, reading a spec sheet, or watching a race in the "wrong" units? Converting between km/h and mph is simple once you know the factor. Here's how.

The exact conversion

1 mile = 1.609 km, so: mph → km/h: multiply by 1.609, and km/h → mph: divide by 1.609 (or multiply by 0.621). For exact figures, use the speed converter.

The mental shortcut

km/h to mph ≈ multiply by 0.6; mph to km/h ≈ multiply by 1.6. So 100 km/h ≈ 60 mph, and 60 mph ≈ 96 km/h. Close enough to read a speedometer or judge a speed limit at a glance.

Common speed limits

30 mph ≈ 48 km/h (town), 60 mph ≈ 97 km/h, 70 mph ≈ 113 km/h (UK motorway), 100 km/h ≈ 62 mph, 120 km/h ≈ 75 mph (European highway). Handy when driving somewhere new.

Why two systems exist

The US and UK (for road speeds) use miles per hour; most of the world uses kilometres per hour. Rental cars, GPS apps and imported vehicles can show either, which is where conversion trips people up.

More conversions

Need distances too? The length converter handles km, miles, metres and feet. For physics-style problems, the speed–distance–time calculator solves for any of the three.