20 mph to m/s — 20 miles per hour in metres per second
Exact 20 ÷ 2.236936 = 8.9408
20 miles per hour in other units
| Metres per second | 8.9408 | m/s |
|---|---|---|
| Kilometres per hour | 32.18688 | km/h |
| Feet per second | 29.333333 | ft/s |
| Knots | 17.379525 | kn |
mph to m/s at a glance
| Miles per hour | Metres per second |
|---|---|
| 1 mph | 0.44704 m/s |
| 2 mph | 0.89408 m/s |
| 3 mph | 1.34112 m/s |
| 5 mph | 2.2352 m/s |
| 10 mph | 4.4704 m/s |
| 20 mph | 8.9408 m/s |
| 25 mph | 11.176 m/s |
| 50 mph | 22.352 m/s |
| 100 mph | 44.704 m/s |
| 250 mph | 111.76 m/s |
| 500 mph | 223.52 m/s |
| 1,000 mph | 447.04 m/s |
How to convert miles per hour to metres per second
Multiply by 0.44704 — one mile per hour is 0.44704 metres per second. That factor is exact: it comes from the definition of the units rather than from a measurement, so it will not change and does not need rounding.
Working 20 ÷ 2.236936 = 8.9408
In words: about nine metres per second.
What these units are
The mile per hour and the metre per second are covered in the speed unit guide, along with every other unit on this page.
Questions
How many metres per second are in a mile per hour?
One mile per hour is 0.44704 metres per second. This figure is exact — it comes from the definition of the unit, not a measurement.
What is 20 miles per hour in metres per second?
20 miles per hour is 8.9408 metres per second. The working is 20 ÷ 2.236936 = 8.9408.
What is a knot?
One nautical mile per hour — and a nautical mile is one minute of latitude, fixed at exactly 1,852 metres. That is the whole point of it: a ship making 10 knots for six hours has covered one degree of latitude, which you can read straight off a chart without converting anything.
Why do sailors and pilots say "knots" and not "knots per hour"?
Because the "per hour" is already inside the word. A knot is a speed, not a distance, so "knots per hour" would be an acceleration. The name comes from the knotted rope once paid out behind a ship and counted against a sand glass.
What's the quick way to convert mph to km/h in my head?
Multiply by 1.6, or add 60%. For the other direction, take away a third and then a little more. Fifty mph is 80 km/h, 60 is 97, 70 is 113 — worth remembering if you drive across a border where the signs change.
Why isn't Mach on this page?
Because it is not a fixed unit. Mach 1 is the local speed of sound, which falls as air gets colder — around 1,235 km/h at sea level but closer to 1,062 km/h in the stratosphere where airliners cruise. A single conversion factor would be wrong nearly everywhere.