How to convert mph to km/h
The international mile is exactly 1,609.344 meters, so 1 mph is exactly 1.609344 km/h. There is no rounding in the factor.
km/h = mph × 1.609344
mph = km/h ÷ 1.609344
m/s = km/h ÷ 3.6
knots = km/h ÷ 1.852A knot is one nautical mile per hour. The international nautical mile is exactly 1,852 meters, so 1 knot is exactly 1.852 km/h, or 1.151 mph. One meter per second is exactly 3.6 km/h.
Worked examples
- 60 mph × 1.609344 = 96.56 km/h, which is 26.82 m/s.
- 100 km/h ÷ 1.609344 = 62.14 mph.
- 130 km/h ÷ 1.609344 = 80.78 mph.
For a quick estimate in your head, multiply mph by 1.6 to get km/h, or multiply km/h by 5 and divide by 8 to get mph. The second trick reads 120 km/h as 75 mph, against an exact 74.56 mph.
Where you meet mph and km/h
- Speedometers: many show one unit in large figures and the other in small ones, and digital dashboards often let you switch. After a tire size change the speedometer reads off in both units; the speedometer calculator shows by how much.
- Tire speed ratings: speed symbols are defined in km/h, and the mph values are conversions. An H rating is 210 km/h, which is 130.49 mph, printed as 130 mph in charts. See the tire speed rating chart for every letter.
- Driving abroad: the US and the UK sign speed limits in mph, most other countries in km/h. A rental car may show a different main unit from your own car. The km/h table helps you read a sign quickly; the limit itself is whatever the sign says.
- Wind and water: marine and aviation speeds are in knots, and some weather services give wind in m/s.
The converter keeps full precision and only rounds what it shows, to two decimals in the boxes and one in the tables.
To turn a speed into minutes per mile or per kilometer for running, use Speed to running pace on laptally.com.
Questions
How fast is 60 mph in km/h?
60 mph is 96.56 km/h. Multiply mph by 1.609344 to get km/h.
How many mph is 100 km/h?
100 km/h is 62.14 mph. Divide km/h by 1.609344 to get mph.
How do I convert km/h to mph in my head?
Multiply by 5 and divide by 8. That gives 75 mph for 120 km/h, close to the exact 74.56 mph. For an exact figure, divide by 1.609344.
How many km/h is 1 knot?
Exactly 1.852 km/h, which is 1.151 mph. A knot is one nautical mile (1,852 m) per hour.