3 mph to km/h — 3 miles per hour in kilometres per hour
Exact 3 × 1.609344 = 4.828032
3 miles per hour in other units
| Metres per second | 1.34112 | m/s |
|---|---|---|
| Kilometres per hour | 4.828032 | km/h |
| Feet per second | 4.4 | ft/s |
| Knots | 2.606929 | 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 3 × 1.609344 = 4.828032
In words: about five kilometres per hour.
What these units are
The mile per hour and the kilometre per hour are covered in the speed unit guide, along with every other unit on this page.
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 3 miles per hour in kilometres per hour?
3 miles per hour is 4.828032 kilometres per hour. The working is 3 × 1.609344 = 4.828032.
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.