Speed converter
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Other units
- Meter per second (m/s) 1
- Kilometer per hour (km/h) 3.6
- Mile per hour (mph) 2.236936
- Foot per second (ft/s) 3.28084
- Knot (kn) 1.943844
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Reviewed on by the Skala Convert team
Speed converts through meters per second. Divide km/h by 3.6 to get m/s; one mph is exactly 1.609344 km/h, and one knot is exactly 1.852 km/h.
How is a speed conversion calculated?
Convert to meters per second, then to the target unit. One kilometer per hour is 1,000 m in 3,600 s, so km/h ÷ 3.6 = m/s. At 100 km/h a car covers 27.8 meters every second — a useful number to keep in mind when thinking about following distance, since even a one-second reaction time means nearly 28 meters traveled before braking begins.
Where does the knot come from?
From a rope. Sailors measured speed by throwing a wooden “log” overboard on a line knotted at regular intervals and counting how many knots ran out in a fixed time. Today a knot is one nautical mile per hour, exactly 1,852 m per hour, or about 1.15 mph. Ships and aircraft use knots because the nautical mile ties distance to latitude on navigation charts.
Is Mach a unit of speed?
Not a fixed one, which is why it is not in this converter. Mach 1 is the speed of sound in the surrounding air, and that depends on temperature: about 343 m/s in air at 20 °C, and noticeably less in the cold air where airliners cruise. The speed of light, by contrast, is exactly 299,792,458 m/s, because the meter has been defined from it since 1983.
For road speeds the two directions people search most are mph to km/h and km/h to mph.
Frequently asked questions
How do I convert km/h to m/s?
Divide by 3.6. 90 km/h is 25 m/s.
How many km/h is one mph?
Exactly 1.609344 km/h.
Is a knot faster than a mile per hour?
Yes. One knot is about 1.151 mph, because a nautical mile is longer than a statute mile.
How fast is the speed of light in km/h?
About 1.08 billion km/h — exactly 299,792,458 m/s.