km/h to mph
Convert speed from km/h to mph.
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Example
100 km/h × 0.621371 = 62.14 mph.
How it works
Kilometres per hour and miles per hour are both units for speed, but they measure distance using different length units. Since 1 mile is about 1.609 kilometres, 1 km/h is only about 0.621371 mph, so multiplying by 0.621371 changes the speed into the equivalent imperial unit. This conversion is exact enough for everyday use because it comes from the standard relationship between kilometres and miles.
When to use it
Use this when you need to understand or compare a speed written in metric units with one written in imperial units. It is common in road travel, sports, vehicle speed comparisons, and reading signs or specifications from different countries.
Worked example, step by step
Convert 72 km/h to mph. 72 km/h × 0.621371 = 44.738712 mph Round to two decimal places: 44.74 mph
Common mistakes to avoid
- Multiplying by 1.609 instead of 0.621371 when converting from km/h to mph
- Using the formula in the wrong direction without switching the conversion factor
- Forgetting to keep the speed units attached to the final answer
Did You Know?
Most of the world posts speed limits in km/h; only a handful of countries, including the US and UK, use mph.
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