Convert Kilometers per Hour to Knots
Kilometers per hour to knots is the conversion sailors, pilots, and meteorologists need, since knots (nautical miles per hour) are the standard speed unit at sea and in the air. The number always gets a bit smaller when you switch from km/h to knots, because a nautical mile is longer than a kilometer.
Kilometers per hour to Knots conversion table
| Kilometers per hour (km/h) | Knots (kn) |
|---|---|
| 1 | 0.539957 |
| 2 | 1.079914 |
| 3 | 1.61987 |
| 5 | 2.699784 |
| 10 | 5.399568 |
| 20 | 10.799136 |
| 50 | 26.99784 |
| 100 | 53.99568 |
| 500 | 269.978402 |
| 1,000 | 539.956803 |
The formula
To convert kilometers per hour to knots, multiply the speed in km/h by 0.539957:
knots = km/h × 0.539957
A worked example
Say a boat's GPS shows a speed of 100 km/h and the crew wants that in knots, the unit used in marine navigation:
100 × 0.539957 = 53.996 kn
That's about 54 knots — a fast speed for most recreational boats, closer to what a powerboat or small aircraft might cruise at.
Why it's an approximation
Knots are tied precisely to kilometers, since one nautical mile is defined as exactly 1.852 kilometers. But turning that relationship around to go from km/h into knots means dividing by 1.852, which produces a repeating decimal that never ends cleanly. 0.539957 is that value rounded to six digits — accurate for navigation and weather work, but a rounded number rather than an exact one.
When you'll use it
Reading marine weather forecasts, following aviation speed reports, converting a boat or aircraft's GPS speed for a logbook, and understanding wind speed reports that mix metric and nautical units.
Frequently asked questions
How many knots is 100 km/h?
About 54.0 knots. Multiply 100 by 0.539957 to get 53.9957, which rounds to 54.0 knots — a typical cruising speed shown on a boat's GPS.
Is the km/h to knots conversion exact?
No, it's a rounded approximation. Knots are tied exactly to kilometers through the nautical mile (1 nautical mile = 1.852 km exactly), but dividing to get km/h into knots produces a repeating decimal, so 0.539957 is a rounded value.
What's a quick way to estimate km/h to knots in my head?
Multiply by roughly 0.54, or just over half. 100 km/h is about 54 knots; 200 km/h is about 108 knots. For anything precise, use the factor above.