What is the MPH to KM/H Converter?
This tool converts a speed expressed in miles per hour (mph) into kilometers per hour (km/h). It is useful for travelers, drivers, runners, cyclists, and anyone comparing speed limits or vehicle speeds between countries that use imperial units (such as the United States and the United Kingdom) and those that use the metric system. The conversion is purely mathematical, so it applies universally.
How to use it
Enter the speed in miles per hour and the calculator instantly returns the equivalent in kilometers per hour. For example, type a highway speed limit in mph to see what it would read on a metric speedometer.
The formula explained
One mile equals exactly 1.609344 kilometers, so one mile per hour equals 1.609344 kilometers per hour. To convert, simply multiply:
$$\text{km/h} = \text{mph} \times 1.609344$$To go the other way, divide kilometers per hour by 1.609344 to get miles per hour.
Worked example
Suppose a car is traveling at 60 mph. Multiply: $$60 \times 1.609344 = 96.56064 \text{ km/h}$$ So 60 mph is about 96.56 km/h — just under 100 km/h, a common metric motorway limit.
FAQ
Is 1.609344 an exact value? Yes. Since 1959 the international mile is defined as exactly 1,609.344 meters, making the factor exact rather than rounded.
What is 70 mph in km/h? \(70 \times 1.609344 = 112.65408\) km/h, roughly 113 km/h.
How do I convert km/h back to mph? Divide by 1.609344. For instance, \(100 \div 1.609344 \approx 62.14\) mph.
