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Convert km/h, mph, and m/s — for driving, sport, and physics.
Convert speeds between kilometers per hour, miles per hour, and meters per second. Useful for driving abroad, running pace, cycling, and physics problems — with exact conversion factors.
Speed units split along the same cultural lines as distance: kilometers per hour dominate worldwide, miles per hour rule in the U.S. and UK, meters per second is the scientific standard, and knots (nautical miles per hour) govern aviation and shipping globally. The conversion factors: 1 mph = 1.609344 km/h; 1 m/s = 3.6 km/h = 2.23694 mph; 1 knot = 1.852 km/h = 1.15078 mph. Because time units are identical on both sides, speed conversion is a single multiplication — simpler than it looks.
The highest-value conversions are the ones that keep you legal and safe. Driving abroad: a 130 km/h French motorway limit is 80.8 mph, while an American 65 mph limit is 104.6 km/h — over a 100 km/h limit, a ticketable difference. Aviation: approach speeds in knots convert to roughly 1.15 times the number in mph. Weather: a 100 km/h wind is 62.1 mph, the threshold of violent-storm force on the Beaufort scale (storm force begins at 89 km/h). Athletics: sprint speeds in m/s (a 10 m/s 100 m runner is moving at 36 km/h) versus road-race pacing in min/km.
Remember that converting speed does not convert pace: runners think in minutes per kilometer, which is the reciprocal of speed, and converting between them needs division, not multiplication. This calculator converts speed units directly; for pace, use the pace calculator.
Every unit converts through meters per second with its exact factor: 1 km/h = 1/3.6 m/s, 1 mph = 0.44704 m/s. The result is value × factor[from] ÷ factor[to].
Multiply by 1.609344: 60 x 1.609344 = 96.5606, rounded to 96.6 km/h. So an American 60 mph zone is just under a 100 km/h limit — close enough that a driver used to kilometers can treat them as equivalent, but not identical. The reverse: 100 km/h / 1.609344 = 62.137 mph, which is why 100 km/h feels like 'about 60' to American drivers. For mental math, the 3-5-8 approximation works: 3 miles is about 5 km, 50 mph about 80 km/h, 80 mph about 130 km/h.
One meter per second equals 2.23694 mph, so 10 x 2.23694 = 22.369, or about 22.4 mph. Equivalently, 10 m/s x 3.6 = 36 km/h, then 36 / 1.609344 = 22.37 mph — same answer by a two-step route. For context, elite 100 m sprinters average just over 10 m/s (a 9.58 s world record is 10.44 m/s, or 23.35 mph), while a fast club runner's 5K pace of 3.3 m/s is only 7.4 mph. The m/s scale makes athletic comparisons intuitive in a way mph never does.
About 62.14 mph. Enter 100, choose km/h → mph — the exact factor is 1 km/h = 0.621371 mph.
Multiply by 3.6 — or use this tool. 10 m/s is exactly 36 km/h.
A knot is one nautical mile per hour (1.852 km/h). This converter covers km/h, mph, and m/s — the units used on roads and in most sports.