300 kilometers per hour is approximately 186.4 miles per hour. To convert, use the factor 1 km=0.621371 miles1\text{ km}=0.621371\text{ miles}1 km=0.621371 miles:
300 km/h×0.621371=186.411 mph300\text{ km/h}\times 0.621371=186.411\text{ mph}300 km/h×0.621371=186.411 mph
