Wind Speed Converter (with Beaufort Scale)

Convert a wind speed between every common unit and find its Beaufort force — from calm (0) to hurricane force (12).

How to use the Wind Speed Converter (with Beaufort Scale)

Enter the wind speed.
Choose its unit.
Read all units plus the Beaufort number and description.

How it works

Wind speeds are reported in knots at sea and in aviation, mph in US forecasts, km/h in most other countries, and m/s in science. The Beaufort scale, devised by Admiral Francis Beaufort in 1805, groups speeds into 13 forces by their visible effects. Thresholds here use the standard knot ranges (for example force 8, a gale, is 34–40 knots).

Beaufort scale

Force	Description	Knots	mph
0	Calm	<1	<1
1	Light air	1–3	1–3
2	Light breeze	4–6	4–7
3	Gentle breeze	7–10	8–12
4	Moderate breeze	11–16	13–18
5	Fresh breeze	17–21	19–24
6	Strong breeze	22–27	25–31
7	Near gale	28–33	32–38
8	Gale	34–40	39–46
9	Strong gale	41–47	47–54
10	Storm	48–55	55–63
11	Violent storm	56–63	64–72
12	Hurricane force	64+	73+

Frequently asked questions

How many mph is a knot?

One knot is about 1.151 mph (1.852 km/h).

What wind speed is a gale?

Beaufort force 8: 34–40 knots (39–46 mph).

What wind speed is hurricane force?

64 knots (74 mph) or more.

What is 20 mph wind in km/h?

About 32 km/h — a fresh breeze (force 5).