kilometre per hour (km/h)
1 kilometre per hour = 0.27777778 metres per second
What is kilometre per hour?
Kilometre per hour is a unit of speed equal to one kilometre travelled in one hour. It is the most widely used unit for road speed limits, vehicle speedometers, and wind speeds in metric countries.
Notes: Common road speed
Real-world uses
Kilometres per hour is the standard speed unit for road traffic in most countries, displayed on car speedometers, speed limit signs, and GPS devices. Weather services report wind speeds in km/h, and athletes track running pace in min/km.
History
Kilometres per hour became widespread as the metric system was adopted for road transport in the 20th century. The first metric speed limits appeared in continental Europe. Today, km/h is used in about 91% of the world's countries for traffic regulation.
Common mistakes
Confusing km/h with m/s—100 km/h is about 27.78 m/s, not 100 m/s. Also, when converting to mph, people often use a rough factor of 1.5 instead of the correct 1.609, leading to inaccurate speed comparisons.
When is this conversion used?
Speed limits, vehicle speedometers, and weather reports for wind speeds use different units depending on the country, making km/h to mph conversion one of the most practical speed conversions.
How to convert kilometre per hour to metre per second
To convert kilometre per hour to metre per second, multiply the value by 0.27777778.
Conversion formula (from base unit)
x * 0.2777777778
Measurement standards
The SI unit of speed is metres per second (m/s), a derived unit requiring no independent definition. The knot is defined as exactly one nautical mile (1,852 metres) per hour and is sanctioned for maritime and aeronautical navigation by the International Civil Aviation Organization.
Did you know?
The fastest human-made object is the Parker Solar Probe, which reached 635,266 km/h (about 176 km/s) in 2024 during a close pass of the Sun — fast enough to travel from New York to Tokyo in under a minute.
| kilometres per hour | metres per second |
|---|---|
| 0.1 | 0.02777778 |
| 0.5 | 0.13888889 |
| 1 | 0.27777778 |
| 2 | 0.55555556 |
| 5 | 1.38888889 |
| 10 | 2.77777778 |
| 25 | 6.94444445 |
| 50 | 13.88888889 |
| 100 | 27.77777778 |
| 250 | 69.44444445 |
| 500 | 138.8888889 |
| 1,000 | 277.7777778 |
Common values
| kilometres per hour | metres per second | |
|---|---|---|
| Walking speed | 5.04 kilometres per hour | 1.4 metres per second |
| City speed limit | 50.04 kilometres per hour | 13.9 metres per second |
| Highway driving | 112.67999999 kilometres per hour | 31.3 metres per second |
| Commercial aircraft | 899.99999993 kilometres per hour | 250 metres per second |
| Speed of sound (sea level) | 1,225.0439999 kilometres per hour | 340.29 metres per second |
Full kilometre per hour conversion table
| Unit | Value | Factor |
|---|---|---|
| metre per second | 1 km/h = 0.27777778 m/s | × 0.27777778 |
| mile per hour | 1 km/h = 0.62137119 mph | × 0.62137119 |
| knot | 1 km/h = 0.5399568 kn | × 0.5399568 |
| foot per second | 1 km/h = 0.91134442 ft/s | × 0.91134442 |
| metre per minute | 1 km/h = 16.66666667 m/min | × 16.66666667 |
| kilometre per second | 1 km/h = 0.00027778 km/s | × 0.00027778 |
| mach (approx at sea level) | 1 km/h = 0.0008163 Ma | × 0.0008163 |
| centimetre per second | 1 km/h = 27.77777778 cm/s | × 27.77777778 |
| mile per minute | 1 km/h = 0.01035619 mi/min | × 0.01035619 |