Wind speed converter: knots, km/h, m/s, mph and Beaufort
Type a wind speed in any unit to see it in all the others, plus the Beaufort force and what it means on the water.
Quick conversion formulas
- knots × 1.852 = km/h
- knots × 0.514 = m/s (or about knots ÷ 2)
- knots × 1.151 = mph
- m/s × 1.944 = knots (or about m/s × 2)
- km/h × 0.540 = knots
Beaufort scale for sailors
| Force | Name | Knots | km/h | m/s | On the water |
|---|---|---|---|---|---|
| 0 | Calm | < 1 | < 1 | < 0.3 | Sea like a mirror. No racing. |
| 1 | Light air | 1 to 3 | 1 to 5 | 0.3 to 1.5 | Ripples. Racing often postponed. |
| 2 | Light breeze | 4 to 6 | 6 to 11 | 1.6 to 3.3 | Small wavelets. Light air racing. |
| 3 | Gentle breeze | 7 to 10 | 12 to 19 | 3.4 to 5.4 | Crests begin to break. Good racing. |
| 4 | Moderate breeze | 11 to 16 | 20 to 28 | 5.5 to 7.9 | Small waves, frequent white horses. |
| 5 | Fresh breeze | 17 to 21 | 29 to 38 | 8.0 to 10.7 | Moderate waves. Hiking hard, smaller sails. |
| 6 | Strong breeze | 22 to 27 | 39 to 49 | 10.8 to 13.8 | Large waves. Upper limit for many dinghy classes. |
| 7 | Near gale | 28 to 33 | 50 to 61 | 13.9 to 17.1 | Sea heaps up. Most racing abandoned. |
| 8 | Gale | 34 to 40 | 62 to 74 | 17.2 to 20.7 | High waves. Stay ashore. |
| 9 | Strong gale | 41 to 47 | 75 to 88 | 20.8 to 24.4 | High waves, dense spray. |
| 10 | Storm | 48 to 55 | 89 to 102 | 24.5 to 28.4 | Very high waves. |
| 11 | Violent storm | 56 to 63 | 103 to 117 | 28.5 to 32.6 | Exceptionally high waves. |
| 12 | Hurricane force | 64 + | 118 + | 32.7 + | Air filled with foam and spray. |
Sailing notes are general guidance. Class rules and sailing instructions set the actual wind limits for each event. For race limits, see what wind speed is too high for a sailing race.
Measure it yourself
Forecasts give an estimate for a wide area. A handheld anemometer tells you the wind where you are, right now. The Windie 360 shows knots, km/h, m/s and mph, and reads from any direction with one hand.
Frequently asked questions
How do I convert knots to km/h?
Multiply knots by 1.852. For example, 15 knots is about 27.8 km/h.
How do I convert knots to m/s?
Multiply knots by 0.514. A quick estimate: divide knots by 2. For example, 20 knots is about 10.3 m/s.
How do I convert m/s to knots?
Multiply m/s by 1.944. A quick estimate: double it. For example, 8 m/s is about 15.6 knots.
How do I convert knots to mph?
Multiply knots by 1.151. For example, 10 knots is about 11.5 mph.
What Beaufort force is 20 knots?
20 knots is Beaufort 5, a fresh breeze.