MPH to KM/H Converter

About MPH to KM/H Converter

Speed is expressed differently depending on context and region — kilometers per hour on most of the world's road signs, miles per hour in the US and UK, meters per second in physics and scientific contexts, and knots specifically in aviation and maritime navigation. Converting accurately between them matters whether you're reading a foreign speed limit sign or working through a physics problem.

This tool converts between five common speed units: meters per second (the SI base unit for speed), kilometers per hour, miles per hour, knots, and feet per second. Each conversion uses an exact defined relationship — a knot, for instance, is defined as exactly one nautical mile (1,852 meters) per hour, a precise value rather than an approximation.

Knots deserve special mention since they're less familiar outside aviation and maritime contexts: a knot is specifically nautical miles per hour, distinct from statute miles per hour used on land. This distinction matters for anyone reading aviation weather reports, boat speeds, or wind speed data, which are conventionally reported in knots.

This is useful for converting a foreign speed limit or speedometer reading, understanding wind speed or aircraft speed reported in knots, physics coursework requiring SI units, or comparing speeds across different contexts that conventionally use different units.

How it works

1. Enter a speed value and select its unit. Any of the five supported speed units.
2. Select the target unit. Or use the swap button to reverse direction.
3. View the exact converted result. Plus the value in every other supported unit at once.