Meters per second to kilometers per hour converter

How to convert m/s to km/h

Multiply meters per second by 3.6: km/h = m/s × 3.6. So 10 m/s is 36 km/h, 25 m/s is 90 km/h, and 343 m/s, about the speed of sound in air at 20 °C, is 1,234.8 km/h. The factor is exact and works for any speed.

Why the factor is 3.6

An hour has 3,600 seconds and a kilometer has 1,000 meters. Moving 1 meter every second covers 3,600 m in an hour, which is 3.6 km, so 1 m/s is exactly 3.6 km/h (NIST SP 811, Appendix B).

Multiply by 4, then take off a tenth

For mental math, multiply by 4 and subtract a tenth of the result: 10 m/s × 4 = 40, and 40 − 4 = 36 km/h. The shortcut is exact, because 4 − 0.4 = 3.6.

m/s to km/h chart

Where m/s figures come from

• Wind reports: many weather services give wind speed in m/s. A 15 m/s wind is 54 km/h.
• Physics answers: SI calculations return speeds in m/s. A ball thrown at 20 m/s is moving at 72 km/h, which is easier to picture.
• Sprint times: 100 m in 10 seconds averages 10 m/s, or 36 km/h.

From speed to distance

Speed times time gives distance once the time units match. At a steady 10 m/s, 30 seconds covers 10 × 30 = 300 meters. With km/h you would first have to turn the 30 seconds into hours, which is why per-second speeds suit short intervals.

Common mistakes

• Dividing by 3.6. That converts km/h to m/s and turns 10 m/s into 2.78 instead of 36. The km/h figure is always the larger one.
• Reading m/s² as m/s. Meters per second squared measure acceleration, a change in speed each second; use the acceleration converter.
• Using 3.6 for meters per minute. One meter per minute is 60 m per hour, or 0.06 km/h.
• Expecting mph. For miles per hour, multiply m/s by about 2.237 instead, or use the speed converter.

Related speed conversions

Use the km/h to m/s converter for the reverse, and mph to km/h for road speeds from the US or UK.