MPH to KM/H: The Complete Guide
Miles per hour (mph) is used for speed limits and vehicle speedometers in the US, UK, and a few other countries. Kilometres per hour (km/h) is used everywhere else. Converting between them is essential when driving abroad or importing vehicles.
The Conversion Formula
km/h = mph × 1.60934Quick mental estimate: multiply by 1.6, or add 60% of the mph value.
Speed Limit Reference Table
- 20 mph = 32.2 km/h
- 30 mph = 48.3 km/h
- 40 mph = 64.4 km/h
- 50 mph = 80.5 km/h
- 60 mph = 96.6 km/h
- 70 mph = 112.7 km/h (UK motorway)
- 100 mph = 160.9 km/h
Driving Abroad
UK speed signs are in mph; France, Germany, and most of Europe use km/h. A hire car speedometer in Germany showing 120 km/h is about 75 mph. The fastest legal road in Europe (some German autobahn sections) has no speed limit — but advisory signs typically say 130 km/h (81 mph).
Convert any speed instantly: Free mph to km/h converter
Complete Reference Table
- 20 mph = 32.2 km/h (urban zone)
- 30 mph = 48.3 km/h
- 40 mph = 64.4 km/h
- 60 mph = 96.6 km/h
- 70 mph = 112.7 km/h (UK motorway limit)
- 75 mph = 120.7 km/h (US highway)
- 100 mph = 160.9 km/h
- 120 mph = 193.1 km/h
Why This Conversion Matters
Speed limits are expressed in mph in the US and UK, and in km/h everywhere else. When driving a hire car in Europe with a US or UK driving licence, failing to understand that a "100" sign means 100 km/h (62 mph), not 100 mph, is both a legal and safety issue. Similarly, vehicle specifications from US manufacturers list top speed and performance figures in mph, while European reviews express the same figures in km/h. F1 and motorsport coverage frequently uses both units, and understanding the relationship helps appreciate the speeds involved. A car reaching 200 km/h is doing 124 mph.
Common Mistakes
- Using the 1.6 approximation for navigation: At highway speeds, the difference between 1.6 and 1.60934 is small but adds up over long distances. For GPS or navigation, always use exact values.
- Misreading speedometers: Many cars sold internationally show both mph and km/h on the speedo. Drivers sometimes misread the outer scale — always verify which scale is active via the dashboard display.
- Wind speed units: Weather forecasts may report wind in mph, km/h, knots, or m/s. These are all different and not interchangeable without conversion. 1 knot = 1.852 km/h ≠ 1 mph (1.609 km/h).
Frequently Asked Questions
How many km/h is 60 mph?
60 mph = 96.561 km/h, often rounded to 96.6 km/h. This is why 100 km/h speed limits (common in Europe) correspond closely to 62 mph, making them roughly equivalent to a 60 mph UK road.
What is the speed of sound in mph and km/h?
The speed of sound in dry air at 20°C is approximately 343 m/s, which equals 1,235 km/h or 767 mph. Aircraft that travel faster than this are said to be supersonic (above Mach 1).
Why do the UK and US still use mph?
Both countries installed road infrastructure using miles before metrication became a global standard, and the cost and disruption of replacing all road signage has been deemed prohibitive. The UK uses km/h only in scientific and some transport contexts; all road signs remain in mph.