How do I convert m/s to km/h?
Multiply by 3.6. To reverse, divide km/h by 3.6 to get m/s.
Speed calculator
Speed converter
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Speed measures distance traveled per unit of time. The SI unit is meters per second (m/s); common everyday units are kilometers per hour (km/h) and miles per hour (mph). 1 m/s equals 3.6 km/h or 2.23694 mph. Aircraft and ships use knots (1 knot = 1.852 km/h = 1.15078 mph).
Example speed conversions
1 m/s3.6 km/h, 2.23694 mph, 1.94384 knots
1 km/h0.2778 m/s, 0.621371 mph, 0.539957 knots
1 mph0.44704 m/s, 1.60934 km/h, 0.868976 knots
1 knot0.51444 m/s, 1.852 km/h, 1.15078 mph
Open the live speed converter for any input value.
Common speed units and their relationships
Meters per second is the SI coherent speed unit and appears in physics equations. Kilometers per hour is the practical metric unit used on road signs and in vehicle speedometers in most of the world. Miles per hour is the US and UK standard for road speeds. Knots (nautical miles per hour) are used in marine navigation and aviation.
Converting between m/s and km/h is simple: multiply by 3.6 to go from m/s to km/h, or divide by 3.6 to reverse. mph to km/h uses the same factor as miles to kilometers (1.609344), since dividing by 'per hour' on both sides leaves the ratio unchanged. Knots to km/h uses 1.852, since 1 knot is one nautical mile per hour and 1 NM is exactly 1,852 meters.
Practical reference speeds
Walking pace is about 5 km/h or 3.1 mph. A brisk walk is around 6.5 km/h or 4 mph. Recreational cycling sits around 20-25 km/h (12-15 mph); competitive cycling routinely hits 40 km/h (25 mph) on flats. Urban driving in metric countries is 50 km/h (31 mph); US residential is typically 25-35 mph (40-56 km/h). Highway speeds are 100-120 km/h (62-75 mph) in most countries, 65-80 mph (105-130 km/h) on US interstates.
Higher up the scale: commercial jets cruise around 850 km/h or 460 knots. The speed of sound in dry air at 20°C is about 343 m/s, equivalent to 1,235 km/h or 767 mph. The speed of light in vacuum is exactly 299,792,458 m/s by definition, since the meter is itself defined in terms of light's travel.
When to use which unit
Engineering and physics calculations use m/s because it integrates cleanly with the rest of SI (forces in newtons, energies in joules). Vehicle and traffic discussions use km/h or mph based on country. Aviation and marine contexts use knots almost exclusively because nautical miles are tied to the geometry of latitude: 1 nautical mile equals 1 minute of arc along a meridian, which makes navigation arithmetic with knots and nautical miles convenient.
Scientific reporting of athlete speeds typically uses m/s for sprints (Usain Bolt's 100m record averaged 10.44 m/s) and km/h for sustained pace (a marathon world record around 21 km/h average).
Common speed conversions
| From | Equivalent |
|---|---|
| 1 m/s | 3.6 km/h, 2.23694 mph, 1.94384 knots |
| 1 km/h | 0.2778 m/s, 0.621371 mph, 0.539957 knots |
| 1 mph | 0.44704 m/s, 1.60934 km/h, 0.868976 knots |
| 1 knot | 0.51444 m/s, 1.852 km/h, 1.15078 mph |
| 50 km/h | 13.89 m/s, 31.07 mph (urban) |
| 60 mph | 26.82 m/s, 96.56 km/h |
| 100 km/h | 27.78 m/s, 62.14 mph (highway) |
| Mach 1 (sea level) | ~343 m/s, 1,235 km/h, 767 mph |
Frequently asked questions
What is a knot in mph?
1 knot equals 1.15078 mph or 1.852 km/h. Knots are used in aviation and marine navigation.
What's a fast walking speed?
About 5 km/h or 3.1 mph for a casual pace; 6-6.5 km/h (4 mph) for brisk walking; 7+ km/h (4.3+ mph) starts to feel like a jog.
Why does aviation use knots instead of mph or km/h?
Knots tie cleanly to nautical miles, which are based on the geometry of latitude: 1 NM equals 1 minute of arc. This makes navigation arithmetic (course, speed, time) easier on charts than statute-mile units would.
What's the speed of sound in different units?
About 343 m/s, 1,235 km/h, 767 mph, or 667 knots, measured in dry air at 20°C. The speed depends on air temperature and density, increasing in warm air and decreasing in cold or thin air.
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