Calckoo
Unit Converters

Speed Converter

Convert between km/h, mph and knots.

Speed units across travel, sport and science

Speed conversion shows up everywhere from road travel (km/h vs mph) to sailing and aviation (knots) to physics (metres per second, the SI base unit). Each field settled on the unit most convenient for its own calculations and instruments, rather than all converging on one standard.

This converter treats metres per second as the common base, since it's the most direct SI unit, then converts to and from the other three on request.

Frequently asked questions

What's a knot, and why do ships and planes use it?

A knot is one nautical mile per hour. Aviation and maritime navigation use it because nautical miles relate directly to degrees of latitude, making navigation calculations more convenient than with km/h or mph.

Why do car speedometers show both km/h and mph?

Vehicles sold across multiple regions often display both, since some countries (most of the world) use km/h while others (the US, UK to a lesser extent) use mph — manufacturers build one speedometer design for multiple markets.

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