About this tool
Enter mph to get km/h; the fields are linked both ways. Hiring a car, reading a US-market dashboard, or following British and American news all run into the mismatch: the United States and the United Kingdom use mph while Taiwan, Japan, and continental Europe use km/h. The factor comes straight from the definition of the mile as 1609.344 metres, so the result is exact. The table covers the speed limits that come up most.