mph to km/h — convert miles per hour to kilometres per hour
Exact 1 × 1.609344 = 1.609344
1 mile per hour in other units
| Metres per second | 0.44704 | m/s |
|---|---|---|
| Kilometres per hour | 1.609344 | km/h |
| Feet per second | 1.466667 | ft/s |
| Knots | 0.86897624 | kn |
mph to km/h at a glance
| Miles per hour | Kilometres per hour |
|---|---|
| 1 mph | 1.609344 km/h |
| 2 mph | 3.218688 km/h |
| 3 mph | 4.828032 km/h |
| 5 mph | 8.04672 km/h |
| 10 mph | 16.09344 km/h |
| 20 mph | 32.18688 km/h |
| 25 mph | 40.2336 km/h |
| 50 mph | 80.4672 km/h |
| 100 mph | 160.9344 km/h |
| 250 mph | 402.336 km/h |
| 500 mph | 804.672 km/h |
| 1,000 mph | 1,609.34 km/h |
How to convert miles per hour to kilometres per hour
Multiply by 1.609344 — one mile per hour is 1.609344 kilometres per hour. 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 1 × 1.609344 = 1.609344
In words: about two kilometres per hour.
Questions
How many kilometres per hour are in a mile per hour?
One mile per hour is 1.609344 kilometres per hour. This figure is exact — it comes from the definition of the unit, not a measurement.
What is 1 mile per hour in kilometres per hour?
1 mile per hour is 1.609344 kilometres per hour. The working is 1 × 1.609344 = 1.609344.
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.