How to convert miles per hour to kilometers per hour
Every mile per hour is 1.6093 kilometers per hour, so the conversion is a single multiplication:
Worked example: 25 mph → 25 × 1.60934 = 40.2335 km/h.
Quick mental estimate: Multiply by 1.6: 25 × 1.6 ≈ 40 km/h (exact: 40.2335).
Miles per hour to kilometers per hour conversion table
| Miles per hour (mph) | Kilometers per hour (km/h) |
|---|---|
| 1 mph | 1.6093 km/h |
| 2 mph | 3.2187 km/h |
| 3 mph | 4.828 km/h |
| 5 mph | 8.0467 km/h |
| 10 mph | 16.0934 km/h |
| 15 mph | 24.1401 km/h |
| 20 mph | 32.1868 km/h |
| 25 mph | 40.2335 km/h |
| 50 mph | 80.467 km/h |
| 75 mph | 120.7 km/h |
| 100 mph | 160.93 km/h |
| 200 mph | 321.87 km/h |
| 250 mph | 402.34 km/h |
| 500 mph | 804.67 km/h |
| 1,000 mph | 1,609.34 km/h |
Values rounded to four decimals. For a value that is not in the table, use the converter above — it accepts decimals and negative numbers.
When you need this conversion
- Driving abroad, where the speedometer and the road signs may not use the same unit.
- Weather reports: wind speeds are published in km/h, mph or knots depending on the service.
- Sport and fitness tracking, where pace and speed settings follow the app’s region.
Getting it right
The arithmetic is a single multiplication, so mistakes almost never come from the calculation itself — they come from the value that goes into it. Check that the figure you are converting really is in miles per hour and not in a neighbouring unit, and that you have not already converted it once.
Sanity-check the direction of the result before you use it. One mile per hour is 1.6093 kilometers per hour, so converting miles per hour to kilometers per hour should make the number larger. If it moved the other way, the conversion was applied backwards — the reverse converter is one click away.
About the units
Mile per hour (mph)
The mile per hour is the speed unit on road signs and speedometers in the United States and the United Kingdom.
Kilometer per hour (km/h)
The kilometer per hour is the speed unit on roads nearly everywhere else in the world, and the unit weather services use for wind speed in most countries.
Frequently asked questions
How many kilometers per hour are in 1 mile per hour?
1 mile per hour equals 1.6093 kilometers per hour. To convert any value, multiply the number of miles per hour by 1.60934.
How do I convert miles per hour to kilometers per hour in my head?
Multiply by 1.6: 25 × 1.6 ≈ 40 km/h (exact: 40.2335).
Is the mph to km/h conversion exact?
1 mile is exactly 1.609344 km, so 1 mph = 1.609344 km/h exactly.
How do I convert miles per hour to kilometers per hour in Excel or Google Sheets?
Put the value in A1 and use =A1*1.60934. Multiplying by the factor works in every spreadsheet, in any programming language, and on a basic calculator.
How many decimal places should I keep?
For everyday use two decimals are plenty. Keep four if the result feeds another calculation, and round only at the very end — rounding intermediate steps is the most common reason a result comes out slightly wrong.