How do I convert Kilometers per hour (km/h) to Miles per hour (mph)?

1 kmh equals 0.621371 mph using SI-based conversion and precise factors.

What is the formula to convert Kilometers per hour (km/h) to Miles per hour (mph)?

This is a linear unit conversion using a constant factor between units.

Yes, it uses exact definitions or standardized constants (e.g., 1 in = 25.4 mm).

Use the shareable URL pattern: /convert/kmh-to-mph/1

Category: Speed

Value From To Precision

0.621371 mph

1 kmh = 0.621371 mph

High-precision rounding: 6 decimals

We convert by pivoting through the SI base unit for Speed and applying exact factors where applicable.

Share this conversion: /convert/kmh-to-mph/1

Speed is distance over time; knots and mph coexist with SI.

Kilometers per hour (km/h)

Common for road speeds.

History: Adopted with metrication of traffic signage.

Miles per hour (mph)

Used in US/UK road speed limits.

History: Follows the international mile.