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Kilometers per hour to miles per hour (km/h to mph)

To convert kilometers per hour to miles per hour (km/h to mph): one kilometer per hour is 0.62137119 miles per hour, so 80 km/h is 49.7097 mph.

Swap units: mph to km/h

In miles per hour49.7097 mph

Conversion factor Exact by definition. The inch has been exactly 2.54 cm and the pound exactly 0.45359237 kg since the 1959 international yard and pound agreement, so these are not measurements that can drift.
1 kilometer per hour = 0.6213711922 miles per hour
The other way
1 mile per hour = 1.609344 kilometers per hour
Working
80 x 0.6213711922 = 49.7097
80 km/h in every unit
22.222 m/s 80 km/h 49.71 mph 72.908 ft/s 43.197 kn
kilometers per hour to miles per hour
km/hmph
10.621371
21.24274
53.10686
106.21371
2515.5343
5031.0686
10062.1371

How the Unit Converter works

One kilometer per hour is 0.6213711922 miles per hour. Both units are defined against the same SI base unit, so the factor is derived from two exact definitions rather than measured. It is exact in principle and does not land on a round number.

Worked through: 80 km/h x 0.621371192 = 49.7097 mph.

Going the other way, one mile per hour is 1.609344 kilometers per hour.

For mental arithmetic: Multiply by 6 and drop a digit: 100 becomes 600, so about 60 mph. True answer 62.1.

Road signs, mostly. The useful landmarks: 50 km/h is 31 mph, 100 km/h is 62 mph, and 120 km/h is 75 mph.

Precision is worth matching to the input. A measurement given as 20 km/h carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.

Unit Converter FAQ

How many miles per hour are in a kilometer per hour?

0.62137119. The factor is derived from the definitions of both units against the same SI base, so it is exact in principle but not a round number.

What is 80 km/h in miles per hour?

49.7097 mph. Multiply by 0.62137119: 80 km/h x 0.621371192 = 49.7097 mph.

How do I convert miles per hour back to kilometers per hour?

Divide by 0.62137119, or equivalently multiply by 1.609344. One mile per hour is 1.609344 kilometers per hour. The two factors are reciprocals, so you only need to remember one of them.

Is there a quick way to do this in my head?

Multiply by 6 and drop a digit: 100 becomes 600, so about 60 mph. True answer 62.1. It is close enough for everyday use.

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