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.
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.
What is knot?
A knot is a unit of speed equal to one nautical mile per hour, approximately 1.852 km/h. It is the international standard for maritime navigation, aviation, and meteorological wind speed reporting.
Real-world uses
Knots are the universal speed unit in maritime navigation and aviation worldwide, regardless of whether a country uses metric or imperial. Ship speeds, ocean currents, wind speed in aviation weather (METAR) reports, and jet stream velocities are all given in knots.
History
The knot originates from the 17th-century practice of measuring ship speed by throwing a log overboard attached to a rope with knots tied at regular intervals. Sailors counted how many knots paid out in a fixed time (measured by a sandglass).
Common mistakes
Saying "knots per hour"—a knot already means nautical miles per hour, so adding "per hour" is redundant and incorrect. Also, confusing knots with km/h: 1 knot ≈ 1.852 km/h.
When is this conversion used?
Converting between kilometre per hour and knot is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. 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.
Worked examples
1 kilometre per hour = 0.5399568 knot
1 knot = 0.51444444 metre per second
How to convert kilometre per hour to knot
To convert kilometre per hour to knot, multiply the value by 0.5399568.
To convert knot back to kilometre per hour, multiply by 1.852.
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.
Quick reference: kilometre per hour to knot
| kilometre per hour | knot |
|---|---|
| 0.1 | 0.05399568 |
| 0.5 | 0.2699784 |
| 1 | 0.5399568 |
| 2 | 1.07991361 |
| 5 | 2.69978402 |
| 10 | 5.39956804 |
| 25 | 13.49892009 |
| 50 | 26.99784018 |
| 100 | 53.99568035 |
| 250 | 134.98920089 |
| 500 | 269.97840177 |
| 1,000 | 539.95680355 |
Common values
| kilometre per hour | knot | |
|---|---|---|
| Walking speed | 5.04 kilometre per hour | 2.72138229 knot |
| City speed limit | 50.04 kilometre per hour | 27.01943845 knot |
| Highway driving | 112.67999999 kilometre per hour | 60.84233262 knot |
| Commercial aircraft | 899.99999993 kilometre per hour | 485.96112315 knot |
| Speed of sound (sea level) | 1,225.0439999 kilometre per hour | 661.47084239 knot |
Available Speed units
More kilometre per hour conversions
- Convert kilometre per hour to metre per second
- Convert kilometre per hour to mile per hour
- Convert kilometre per hour to knot
- Convert kilometre per hour to foot per second
- Convert kilometre per hour to metre per minute
- Convert kilometre per hour to kilometre per second
- Convert kilometre per hour to mach (approx at sea level)
- Convert kilometre per hour to centimetre per second
- Convert kilometre per hour to mile per minute
Assumption: Mach uses an approximate sea-level reference (about 340.29 m/s).