Speed Converter: km/h, mph, m/s, Knots and ft/s

How speed conversion works

A speed is a distance divided by a time, so each unit converts through meters per second:

Result = Value × (m/s per “from” unit) ÷ (m/s per “to” unit)

Because the mile is exactly 1,609.344 m, 1 mph is exactly 1,609.344 m ÷ 3,600 s = 0.44704 m/s, and 1 km/h is 1,000 m ÷ 3,600 s ≈ 0.2778 m/s.

Example: 100 km/h ÷ 1.609344 = 62.13711922 mph. In the other direction, 60 mph × 1.609344 = 96.56064 km/h.

Speed units and their exact value in meters per second
Unit	In m/s	Defined as
1 km/h	0.2777777778 m/s	1,000 m per 3,600 s
1 mph	0.44704 m/s	1,609.344 m per 3,600 s
1 knot (kn)	0.5144444444 m/s	1 nautical mile (1,852 m) per hour
1 ft/s	0.3048 m/s	0.3048 m per second
1 m/s	3.6 km/h	SI unit of speed

Speed limits: km/h and mph

Most countries post speed limits in km/h. The United States and the United Kingdom use mph. The tables below give exact conversions rounded to 0.1; they are unit conversions only, so always follow the posted limit.

Kilometers per hour to miles per hour
km/h	mph
30 km/h	18.6
50 km/h	31.1
60 km/h	37.3
80 km/h	49.7
90 km/h	55.9
100 km/h	62.1
110 km/h	68.4
120 km/h	74.6
130 km/h	80.8

Miles per hour to kilometers per hour
mph	km/h
20 mph	32.2
30 mph	48.3
40 mph	64.4
50 mph	80.5
60 mph	96.6
70 mph	112.7
80 mph	128.7

Where each unit is used

km/h for road speeds in most of the world. mph for road speeds in the United States and the United Kingdom. Knots at sea and in aviation, because one knot is one nautical mile per hour. m/s in science and engineering, and by some weather services for wind speed. ft/s in some US engineering and ballistics contexts.

Common questions

How do I get km/h from a running pace?

Divide 60 by the minutes per kilometer: a pace of 5 minutes per km is 60 ÷ 5 = 12 km/h, or 7.5 mph. To find a finishing time from a speed and a distance, divide the distance by the speed.

Is a knot the same as a mile per hour?

No. A knot is a nautical mile (1,852 m) per hour, so 1 knot is about 1.151 mph or exactly 1.852 km/h.

Why is there no Mach number here?

Mach is speed relative to the speed of sound, which changes with air temperature and altitude, so it has no single fixed conversion to km/h or mph.