Miles per hour (mph) and Meters per second (m/s) explained
Miles per hour is the speed unit of US and UK road traffic, American weather reporting and most consumer-facing sports coverage in those countries. Meters per second is the SI coherent unit of speed and the one every physics equation expects: kinetic energy, momentum, drag and projectile motion all break if you feed them mph. Scientific and engineering work — wind tunnel data, ballistics, biomechanics, meteorological models — is done in m/s and only converted to mph for publication. That mismatch is exactly where the conversion is needed: taking a number from a news report or a speed limit sign and putting it into a calculation.
Formula and worked examples
m/s = mph × 0.44704The factor is 1,609.344 ÷ 3,600 = 0.44704, exactly. A 30 mph urban limit is 13.41 m/s. A 60 mph highway speed is 26.82 m/s. A 100 mph fastball travels at 44.7 m/s. Hurricane-force wind starts at 74 mph, which is 33.08 m/s — just above the 32.7 m/s threshold that defines force 12 on the Beaufort scale.
Miles per hour (mph) to Meters per second (m/s) conversion table
Common Miles per hour (mph) values converted to Meters per second (m/s). Every figure uses the same conversion factor as the calculator above.
| Miles per hour (mph) | Meters per second (m/s) |
|---|---|
| 1 | 0.44704 |
| 2 | 0.89408 |
| 5 | 2.2352 |
| 10 | 4.4704 |
| 20 | 8.9408 |
| 50 | 22.352 |
| 100 | 44.704 |
Where you will use this
Physics and engineering homework
Kinetic energy is ½mv² with v in m/s. A 1,500 kg car at 60 mph carries ½ × 1500 × 26.82² ≈ 539 kJ. Using 60 directly instead of 26.82 overstates the energy by a factor of five.
Reading wind speed data
US forecasts give wind in mph while meteorological models and engineering wind loads use m/s. A 45 mph gust is 20.1 m/s, the number a structural load table will be indexed on.
Sports performance analysis
Baseball pitch speeds, tennis serves and sprint splits are broadcast in mph but analysed in m/s. A 10-second 100 m sprint averages 10 m/s, or 22.37 mph, which puts televised pitch speeds in useful perspective.