Knots to km/h and m/s
A knot (kn) is one nautical mile per hour, which is exactly 1.852 km/h or 0.5144 m/s. Type a speed and the converter shows it in every unit at once, with the Beaufort force read from the WMO thresholds on top.
Quick try:
The Beaufort force is read from the WMO thresholds of the unit you typed in. A knot is one nautical mile per hour, which is exactly 1.852 km/h.
Common speeds converted
| kn | km/h | m/s | mph |
|---|---|---|---|
| 1 | 1.852 | 0.5144444 | 1.150779 |
| 5 | 9.26 | 2.572222 | 5.753897 |
| 10 | 18.52 | 5.144444 | 11.50779 |
| 12 | 22.224 | 6.173333 | 13.80935 |
| 15 | 27.78 | 7.716667 | 17.26169 |
| 20 | 37.04 | 10.28889 | 23.01559 |
| 25 | 46.3 | 12.86111 | 28.76949 |
| 30 | 55.56 | 15.43333 | 34.52338 |
Values computed from the exact definitions of the units (NIST SP 811 and the international agreements), rounded to 7 significant digits. The first column is knots.
Where the knot comes from
The name comes from the chip log: a line with knots tied every 47 feet 3 inches was streamed astern and the crew counted how many knots ran through their hand while a 30 second sand glass emptied. The count was the speed in nautical miles per hour, no calculation needed.
Because a nautical mile equals one minute of latitude, speed in knots translates straight into work on the chart: a ship doing 12 knots covers 12 minutes of latitude in an hour. That is why the sea and aviation stayed with knots while the road went metric.
Frequent questions
How many km/h is 1 knot?
Exactly 1.852 km/h. It is not a rounding: the nautical mile is defined as 1852 metres, and a knot is one nautical mile per hour.
How do I convert knots to m/s in my head?
Halve it and add a little: 1 knot is 0.5144 m/s. So 20 knots is about 10.3 m/s. The other way round, double the m/s and you get knots slightly on the low side.
How fast does a merchant ship go?
Service speed is usually 10 to 16 knots: bulk carriers and tankers nearer 11 to 14, container ships 16 to 22. Fast ferries and warships run at 25 to 30 and above.
Is a knot in aviation the same unit?
Yes. Aviation uses exactly the same knot for airspeed and wind, for the same reason as the sea: navigation built on nautical miles and minutes of arc.