🚗 Mph to Km/h Converter

Convert miles per hour to kilometers per hour, both directions.

About this tool

Converts miles per hour to kilometers per hour using the exact factor 1 mph = 1.609344 km/h.

Useful for reading car speedometers, wind speeds, and speed limits when crossing between imperial and metric countries.

Worked example

A 65 mph highway speed limit is about 104.6 km/h, and a 100 km/h limit is about 62.1 mph.

How to use it

Enter a value in mph.
The km/h equivalent appears instantly.
Swap direction to convert km/h back to mph.

Tips

Most car speedometers show both scales on the dial — this tool is handy for a fast double-check while renting a car abroad.
Wind and weather reports mix mph and km/h depending on the country's convention — worth a check before assuming which one a forecast means.
The conversion factor is identical to the miles-to-km one, since both are just distance-per-hour.

FAQ

How fast is 100 km/h in mph?

100 km/h is about 62.1 mph.

Do all countries use km/h for speed limits?

Most do — the US, UK, and a small number of others are the main exceptions still using mph on road signs.

Is this the same formula as the miles-to-km converter?

Yes — mph to km/h uses the identical 1.609344 factor, just applied to a speed instead of a distance.

From the blog: getting the most out of this tool

Renting a car in a country that uses the "other" speed unit is the classic use case here — a quick gut-check on whether 120 on the dial is comfortably legal or well over the limit.

We used the same conversion engine as our Miles to Km page since speed is just distance over time — that consistency means the numbers always agree between the two tools.

📖 Want the fuller explanation?

See Metric vs Imperial Units for the reasoning behind this calculation, with worked examples.