About Speed Conversion

Speed conversion between miles per hour (mph) and kilometers per hour (km/h) is crucial for international travel, automotive specifications, weather reporting, and sports. The conversion factor is standardized internationally with 1 mile exactly equal to 1.609344 kilometers.

How to Use This Converter

Enter your speed value in the input field
Select appropriate units in the "From" and "To" dropdowns
View instant conversion results
Use the swap button to reverse units
Adjust decimal precision using the slider

Common Speed Conversions

mph	km/h
10	16.09
30	48.28
50	80.47
70	112.65
100	160.93

Important Notes

1 mph equals exactly 1.609344 km/h by international agreement
The knot (nautical mile per hour) is different from both units
Some countries use both systems simultaneously (e.g., UK uses mph for roads but km/h for weather)

Frequently Asked Questions

Why is the conversion factor 1.609344?

This exact value comes from the international definition of 1 mile = 1760 yards = 5280 feet = 1609.344 meters, making 1 mph = 1.609344 km/h exactly.

Are there different types of miles that affect conversion?

The international mile (used in this converter) is standard. Nautical miles (1.852 km) and historical miles (varying by country) differ but are not used in road speed measurements.

How precise should I be with speed conversions?

For most practical purposes, 1-2 decimal places are sufficient. Automotive applications typically round to the nearest whole number.

Miles per Hour to Kilometers per Hour Converter

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Miles per Hour to Kilometers per Hour Converter

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