🚀 Speed

Speed Converter

Road signs in km/h, a boat's speed in knots, a plane at Mach 0.8 — convert between every common unit of speed. Enter the value and press Convert.

Written and reviewed by SM Arijul Islam · Last reviewed 28 October 2026 · Editorial standards · Report an error

About the speed converter

Speed describes distance covered per unit of time. The SI unit is metres per second, but daily life uses km/h in most of the world and mph in the United States and the United Kingdom. Aviation and marine navigation use knots, one nautical mile per hour.

Key conversion factors

1 km/h = 0.277778 m/s · 1 m/s = 3.6 km/h
1 mph = 1.609344 km/h exactly
1 knot = 1.852 km/h exactly
Mach 1 ≈ 340.29 m/s ≈ 1,225 km/h at sea level, 15 °C
Speed of light = 299,792,458 m/s exactly

Mach number depends on air temperature, so the value shown is the standard sea-level approximation.

How to convert speed

Speed is distance divided by time. The SI unit is metres per second, but everyday measures include kilometres per hour and miles per hour. Knots, equal to one nautical mile per hour, are standard at sea and in the air because a nautical mile corresponds closely to one arcminute of latitude. Because the units combine two base quantities, the conversion factors are not obviously related — 1 m/s is exactly 3.6 km/h.

Common speed conversions

One kilometer per hour expressed in other units of speed
Unit	1 kilometer per hour equals
Foot per second (ft/s)	0.91134442
Mile per hour (mph)	0.62137119
Knot (kn)	0.5399568
Meter per second (m/s)	0.27777778
Mach (sea level) (Ma)	0.00081629721
Kilometer per second (km/s)	0.00027777778

Everyday uses

Driving, speed limits and road trips
Aviation and marine navigation
Running, cycling and pace training
Wind speed and weather reporting
Physics problems and experiments

Frequently asked questions

How many kilometres per hour is one metre per second?

Exactly 3.6 km/h, because there are 3,600 seconds in an hour and 1,000 metres in a kilometre.

What is a knot?

One nautical mile per hour — about 1.852 km/h or 0.514444 m/s.

How do I convert mph to km/h?

Multiply by 1.609344, so 60 mph is about 96.6 km/h.

What is Mach 1?

The speed of sound, about 1,225 km/h at sea level and 15 °C, though it varies significantly with temperature and altitude.

More worked examples

100 km/h is about 62.14 mph.
60 mph is about 96.56 km/h.
One metre per second is exactly 3.6 km/h.
A speed of 20 knots is about 37.04 km/h.

Quick reference

Common exact speed conversion factors
Conversion	Exact value
1 m/s	3.6 km/h
1 km/h	0.277778 m/s
1 mph	1.609344 km/h
1 km/h	0.621371 mph
1 knot	1.852 km/h
1 m/s	2.236936 mph
1 foot per second	0.3048 m/s

Common mistakes to avoid

Confusing speed with pace. They are reciprocals, so a faster speed means fewer minutes per kilometre.
Using 1.6 as the kilometre to mile factor for anything precise. The exact figure is 1.609344.
Mixing km/h and m/s inside one physics calculation, which is a factor of 3.6 error.
Assuming knots and miles per hour are close. A knot is about 15 percent faster than a mile per hour.

Further questions

How do I convert km/h to m/s?

Divide by 3.6. For example, 100 km/h is 27.78 m/s.

How do I convert speed into running pace?

Divide 60 by the speed in km/h to get minutes per kilometre. At 12 km/h the pace is 5 minutes per kilometre.

Why does the United Kingdom still use miles per hour?

Road signage and long-standing convention. Most other areas of British life have moved to metric.

Sources and standards

Speed is length divided by time, so its factors come from the definitions of the metre and the second. The knot is exactly 1,852 m/h by international agreement, and NIST SP 811 gives the exact mile per hour factor applied here.

kmh to mph and mph to kmh

kmh to mph multiplies by 0.6213711922, and mph to kmh multiplies by 1.609344, because a mile is exactly 1,609.344 m. So 100 km/h is 62.14 mph and 60 mph is 96.56 km/h — close enough that people confuse them, but a real 3.4 km/h apart.

Kilometres per hour and miles per hour equivalents
km/h	mph	mph	km/h
30 km/h	18.64 mph	30 mph	48.28 km/h
50 km/h	31.07 mph	50 mph	80.47 km/h
80 km/h	49.71 mph	60 mph	96.56 km/h
100 km/h	62.14 mph	70 mph	112.65 km/h
130 km/h	80.78 mph	100 mph	160.93 km/h

Dedicated pages: km/h to mph and mph to km/h.