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

1 mph equals 1.609344 kmh using SI-based conversion and precise factors.

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

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/mph-to-kmh/1

Category: Speed

Value From To Precision

1.609344 kmh

1 mph = 1.609344 kmh

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/mph-to-kmh/1

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

Miles per hour (mph)

Used in US/UK road speed limits.

History: Follows the international mile.

Kilometers per hour (km/h)

Common for road speeds.

History: Adopted with metrication of traffic signage.