Mph to km/h
One mph equals 1.609344 km/h. Type any number and the answer appears as you type — the maths happens in your browser.
The same value in every unit
| Unit | Value |
|---|
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Common values
| mph | km/h |
|---|---|
| 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 |
| 15 mph | 24.14016 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 |
| 500 mph | 804.672 km/h |
| 1000 mph | 1609.344 km/h |
How to use
- Enter the number of mph in the field.
- The result in km/h updates on every keystroke.
- Use the table below for the values people look up most often.
Formula and reverse conversion
The formula
To convert by hand: km/h = mph × 1.609344. Going back the other way, one km/h is 0.6213711922 mph.
Where the odd number comes from
The factor is not a round number because the imperial units are defined through the metric ones by international agreement: an inch is exactly 25.4 mm and a pound is exactly 0.45359237 kg. Everything else follows from those definitions.
km/h = mph × 1.609344
Frequently asked questions
How many km/h are in one mph?
One mph is 1.609344 km/h.
How do I convert mph to km/h?
Multiply by the factor: km/h = mph × 1.609344.
Is the result exact?
The factors are the exact legal definitions, and up to ten significant digits are kept in the answer. Rounding happens only in the display.
How do I convert km/h back to mph?
One km/h is 0.6213711922 mph — or open the reverse page linked below.