Wind Speed Converter with the Beaufort Scale
To convert m/s to km/h, multiply by 3.6. To convert km/h to mph, multiply by 0.6214. A 10 m/s wind is 36 km/h, 22.4 mph or 19.4 knots, which is Force 5 (a fresh breeze) on the Beaufort scale.
Metres per second
10.00 m/s
Kilometres per hour
36.00 km/h
Miles per hour
22.37 mph
Knots
19.44 kn
Feet per second
32.81 ft/s
Beaufort scale
Force 5 · Fresh breeze
Small trees in leaf begin to sway.
| Force | Description | Knots |
|---|---|---|
| 0 | Calm | 0–0 |
| 1 | Light air | 1–3 |
| 2 | Light breeze | 4–6 |
| 3 | Gentle breeze | 7–10 |
| 4 | Moderate breeze | 11–16 |
| 5 | Fresh breeze | 17–21 |
| 6 | Strong breeze | 22–27 |
| 7 | Near gale | 28–33 |
| 8 | Gale | 34–40 |
| 9 | Strong gale | 41–47 |
| 10 | Storm | 48–55 |
| 11 | Violent storm | 56–63 |
| 12 | Hurricane force | 64+ |
Show the math
- 1
Convert to metres per second
10 m/s is already the base unit
Every unit is converted through metres per second so the answers stay consistent.
= 10 m/s
Read the steps as text
- Convert to metres per second. 10 m/s is already the base unit Every unit is converted through metres per second so the answers stay consistent.
- Convert to km/h. 10 × 3.6 = 36 km/h
- Convert to mph. 10 × 2.2369 = 22.369 mph
- Convert to knots. 10 × 1.9438 = 19.438 knots A knot is one nautical mile per hour, used at sea and in aviation.
- Find the Beaufort force. 19.4 knots falls in force 5: Fresh breeze Small trees in leaf begin to sway.
Wind speed units
Forecasters use different units in different places. Metres per second is the scientific standard, kilometres per hour is used across most of the world, miles per hour in the United States and the UK, and knots at sea and in aviation. A knot is one nautical mile per hour, or 1.852 km/h.
The calculator converts everything through metres per second, so the results always agree with each other. The conversion factors are: 1 m/s = 3.6 km/h = 2.237 mph = 1.944 knots = 3.281 ft/s.
The Beaufort wind scale
The Beaufort scale describes wind by its effects rather than by instruments. It was devised in 1805 by Royal Navy officer Francis Beaufort to describe the wind at sea and later extended to land. Force 0 is calm, with smoke rising straight up. Force 4 raises dust and small branches move. Force 8 is a gale, when twigs break off trees and walking is difficult. Force 12, from 64 knots (about 119 km/h or 74 mph), is hurricane force.
The flag in the calculator lifts and flutters harder as the Beaufort force rises, so you can see the difference between a breeze and a gale. The table below the results highlights your force.
Gusts, averages and safety
Forecast wind speeds are usually averaged over about ten minutes, and gusts can be 30 to 50% higher. Wind measured at 10 metres high, the weather-station standard, is stronger than what you feel at ground level among buildings and trees. Sailors, pilots, cyclists and drone flyers all have wind limits, so check the limit for your activity in the unit it is given in.
Frequently asked questions
- How do I convert mph to km/h?
- Multiply by 1.609. For example, 30 mph is about 48 km/h. To go the other way, multiply km/h by 0.6214.
- What wind speed is a gale?
- A gale is Force 8 on the Beaufort scale: 34 to 40 knots, which is about 62 to 74 km/h or 39 to 46 mph.
- What wind speed is a hurricane?
- Hurricane force is 64 knots or more, roughly 119 km/h or 74 mph. Hurricanes are then rated by category on the Saffir-Simpson scale.
- What is a knot?
- One nautical mile per hour, equal to 1.852 km/h or 1.151 mph. Nautical miles are based on the geometry of Earth, which is why sailors and pilots use them.