How do I convert km/h to mph?

Multiply km/h by 0.621371. So 100 km/h ≈ 62.1 mph. Going the other way, multiply mph by 1.60934.

A knot is one nautical mile per hour, about 1.852 km/h or 1.15 mph. It is standard in aviation and maritime travel.

Mach 1 is the speed of sound, which varies with air temperature. At sea level in standard conditions it is about 340.3 m/s (1,225 km/h). This converter uses the sea-level value.

Speed Converter

Convert speed and velocity — m/s, km/h, mph, knots, and feet per second. For travel, physics, and engineering.

Converters

Meters per second m/s

Kilometers per hour km/h

Miles per hour mph

Feet per second ft/s

Knot kn

Mach (sea level) Ma

About the speed converter

Speed mixes everyday units (km/h, mph) with scientific (m/s) and specialized ones (knots for aviation and sailing). The knot is one nautical mile per hour — which is why it pairs naturally with nautical navigation.

Conversion reference

1 m/s	=	1 m/s	Meters per second
1 m/s	=	3.6 km/h	Kilometers per hour
1 m/s	=	2.2369363 mph	Miles per hour
1 m/s	=	3.2808399 ft/s	Feet per second
1 m/s	=	1.9438445 kn	Knot
1 m/s	=	0.00293867 Ma	Mach (sea level)

All conversions run entirely in your browser — nothing is sent to a server. Factors are exact wherever an exact definition exists.