Why pilots need to convert
Drone spec sheets quote the wind limit in m/s or as a "level", weather apps show km/h or mph, and aviation reports (METAR, TAF) use knots. Mixing them up is an easy way to misread a forecast by a factor of three or four.
The conversion factors
| From | To km/h |
|---|---|
| 1 m/s | 3.6 km/h |
| 1 knot | 1.852 km/h |
| 1 mph | 1.609 km/h |
So 10 m/s is 36 km/h, 22 mph or 19.4 knots. To go from km/h to m/s, divide by 3.6.
The Beaufort scale and your drone
The Beaufort scale sorts wind into forces by its effects. DJI uses it for its "Level 5" wind resistance (up to 10.7 m/s). The ranges below are the standard ones from the World Meteorological Organization, at 10 m above the ground; the drone column is a rule of thumb for consumer camera drones.
| Force | Name | m/s | km/h | For a consumer drone |
|---|---|---|---|---|
| 0–2 | Calm to light breeze | below 3.4 | below 12 | Easy flying for any drone |
| 3 | Gentle breeze | 3.4–5.4 | 12–19 | Fine; small drones drift a little |
| 4 | Moderate breeze | 5.5–7.9 | 20–28 | Noticeable for sub-250 g drones; check the gusts |
| 5 | Fresh breeze | 8.0–10.7 | 29–38 | The rated limit of Mini-class drones ("Level 5") |
| 6 | Strong breeze | 10.8–13.8 | 39–49 | Beyond most small drones; only larger models rated for 12 m/s or more |
| 7+ | Near gale and above | 13.9 and up | 50 and up | Do not fly a consumer drone |
Remember that these are 10 m values: at 100–120 m the same day is often one or two forces windier (see the wind at altitude calculator).
Frequently asked questions
How do I convert m/s to km/h?
Multiply by 3.6. A drone rated for 12 m/s handles about 43 km/h; one rated for 10.7 m/s handles about 38 km/h.
What does "Level 5 wind resistance" mean?
It refers to force 5 on the Beaufort scale, a fresh breeze of up to 10.7 m/s (38 km/h). DJI uses it for its Mini drones.
How many km/h is a knot?
One knot is one nautical mile per hour, exactly 1.852 km/h. 20 knots is 37 km/h.