Speed Converter
Convert between metres per second, kilometres per hour, miles per hour, knots, feet per second and Mach. Results update as you type. Last updated: June 2026.
Best for: Converting kilometres per hour to miles per hour when reading a foreign spec sheet, and translating metres per second for physics homework
Limitations: Covers common speed units rather than aviation or nautical specialist measures beyond knots
Best suited for: Students and travellers reading figures quoted in an unfamiliar unit system
Popular Speed Conversions
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Speed Reference Points
Mach number is the ratio of speed to the local speed of sound. It varies with air temperature and altitude. The value of 340.29 m/s used here is for dry air at sea level at 15°C.
Frequently Asked Questions
How many mph is 100 km/h?
100 km/h = 62.14 mph. To convert km/h to mph, multiply by 0.621371. To convert mph back to km/h, multiply by 1.60934. The typical highway speed limit of 100 km/h is just over 62 mph.
What is a knot in km/h?
1 knot = 1.852 km/h exactly. A knot is one nautical mile per hour. Nautical miles are used in maritime and aviation navigation because they relate directly to degrees of latitude on Earth's surface.
What is Mach 1 in km/h?
Mach 1 is approximately 1, 235 km/h (767 mph) at sea level and 15°C. The speed of sound changes with air temperature and altitude. Commercial aircraft cruise at roughly Mach 0.85, and the Concorde flew at Mach 2.
How do I convert km/h to m/s?
Divide by 3.6. Since 1 km = 1, 000 m and 1 hour = 3, 600 seconds, the factor is 1, 000 / 3, 600 = 1/3.6. Example: 72 km/h ÷ 3.6 = 20 m/s. To go the other way, multiply m/s by 3.6.
What is 60 mph in km/h?
60 mph × 1.60934 = 96.56 km/h. A quick mental check: 60 mph is just under 100 km/h. The exact factor is 1.60934 km per mile.
How Does the Speed Converter Work?
Speed conversions combine a length conversion with a time conversion, so the converter reduces your input to metres per second before converting out. Doing it in one step avoids the error that creeps in when people convert the distance and the time separately and round at each stage. Because both components have exact definitions, the resulting factors are exact too.
The base units involved are defined in the BIPM SI Brochure.
Common Speed Conversions and When You Need Them
Driving is the common case. Speed limits are posted in kilometres per hour across most of the world and in miles per hour in the United States and the United Kingdom, and 100 km/h is about 62 mph. Hire cars and imported vehicles often display the unfamiliar one.
Running and cycling pace is the second, where a pace in minutes per kilometre has to be reconciled with a speed in miles per hour. Aviation and sailing are the third, using knots, where one knot is one nautical mile per hour or about 1.852 km/h. Wind speed reporting is the fourth, mixing metres per second in scientific use with km/h in forecasts.
What Are the Standard Speed Measurements?
The metre per second is the SI coherent derived unit for speed, following directly from the metre and the second. The kilometre per hour is widely used but not coherent, being 1/3.6 of a metre per second. The knot is defined as exactly one nautical mile per hour, and since the nautical mile is exactly 1,852 metres, one knot is exactly 0.514444 metres per second recurring.