Speed Converter
Convert between mph, km/h, m/s, knots and more instantly. Type any value to update all fields simultaneously.
Common Speed Conversions
How many km/h in 1 mph?
1 mile per hour = 1.60934 kilometres per hour. To convert mph to km/h, multiply by 1.609. For a rough mental estimate, multiply by 1.6. So 60 mph ≈ 96.6 km/h, and 70 mph (UK motorway limit) ≈ 112.7 km/h.
What is a knot and how does it compare to mph?
A knot is 1 nautical mile per hour. 1 nautical mile = 1,852 metres (the length of 1 arc-minute of latitude). 1 knot ≈ 1.15078 mph or 1.852 km/h. Knots are used in aviation and maritime navigation because nautical miles directly relate to latitude, simplifying navigation calculations.
What is Mach 1 in mph?
Mach 1 (the speed of sound at sea level, 15°C) ≈ 340.29 m/s ≈ 761.2 mph ≈ 1,225 km/h. The speed of sound varies with altitude and temperature — at cruising altitude (~35,000 ft) it drops to about 295 m/s (660 mph), which is why aircraft Mach numbers matter more than absolute speeds at altitude.
Why does the UK still use mph for road speeds?
Despite the UK's official adoption of the metric system, road speed limits and speedometers remain in miles per hour under the Traffic Signs Regulations. This is retained largely due to cultural familiarity and the cost of changing road signage across the entire network. There is no current government plan to switch to km/h.