Miles per hour Converter

A mile per hour is one statute mile, exactly 1,609.344 meters, travelled in one hour. Miles per hour and kilometers per hour relate by exactly 1.609344, and one mile per hour is exactly 0.44704 meters per second.

It is used on road signs and in vehicle speed limits, in motoring and tyre specifications, in wind and weather reports, and in aviation and motorsport figures.

One mile per hour is exactly 1.609344 km/h, and that metric relationship needs no rounding. A knot is not a mile per hour, since one uses the nautical mile of 1,852 meters and the other the statute mile.

Treating a mile per hour as a knot is the usual mistake, because both count distance over an hour. A vessel or aircraft figure in knots needs the nautical mile before it can be compared with road speed.

The siblings are kilometers per hour, knots and meters per second. Posted road speeds in miles per hour belong to this unit, metric road and wind figures belong to kilometers per hour, navigation belongs to knots, and scientific measurement belongs to meters per second.

Every speed unit is a distance over a time, so the conversion factor is just the distance factor divided by the time factor. Meters per second to kilometers per hour is a single multiplication by exactly 3.6, and a reader can hold that number.

The candidates for confusion are the mile and the nautical mile, because both appear in speed units. A knot is one nautical mile per hour, and a nautical mile is 1,852 meters against the statute mile's 1,609.344, so a knot is about 15% faster than a mile per hour. Treating the two as interchangeable understates a marine or aviation speed.

To check a speed conversion, convert it to meters per second and compare with something known, such as walking pace. The error to avoid is applying the 3.6 factor to a pair that is not m/s to km/h, when the correct move is to convert the distance and the time separately.