The exact equivalent
One knot is exactly 1.852 kilometres per hour, because it is one nautical mile per hour and a nautical mile is 1,852 metres.
1 kn = 1.852 km/h
1 km/h = 0.5399568 kn
How to convert it by hand
Just multiply by the conversion factor. To go from knots to kilometres per hour, multiply by 1.852; to come back, divide by that same number or multiply by 0.539957.
For example: 25 kn × 1.852 = 46.3 km/h.
A tip that saves mistakes: check the result goes the way you expect. If kilometres per hour are a smaller unit than knots, the number has to come out bigger. If it comes out smaller, you divided when you should have multiplied.
Conversion table
| kn | km/h |
|---|---|
| 1 | 1.852 |
| 2 | 3.704 |
| 5 | 9.26 |
| 10 | 18.52 |
| 20 | 37.04 |
| 50 | 92.6 |
| 100 | 185.2 |
Reference points to picture it
| Reference | Equals |
|---|---|
| A brisk sailing wind | 15 kn = 27.8 km/h |
| A gale | 34 kn = 63 km/h |
| A cruising airliner | 480 kn = 889 km/h |
| A container ship | 20 kn = 37 km/h |
The trick for doing it in your head
Multiply by 2 and take off 7.5%. For 20 knots: 40 minus 3 gives 37 km/h, and the true answer is 37.04.
It is fine for getting by without a phone, but not for anything that depends on precision: in a recipe, on a building site or in a dose, use the exact conversion.