Crosswind calculator

Runway (e.g. 27) or direction in degrees Wind direction (degrees) Wind speed (kt) Gusts (kt, optional)

Enter runway, wind direction and wind speed.

How the calculator works

The calculator finds the angle between the wind direction and the runway direction. The crosswind component is the wind speed times the sine of that angle, the along-runway component the wind speed times the cosine. If the along-runway component is negative, the wind comes from behind. A two-digit runway number such as 27 is converted to 270 degrees.

The FAA Pilot’s Handbook of Aeronautical Knowledge shows the same split as a chart: for runway 17 and a wind from 140 degrees at 25 knots, the angle is 30 degrees, with about 22 knots of headwind and 13 knots of crosswind. The calculator gives 21.7 and 12.5 knots; the chart can only be read more roughly.

True or magnetic

Item	Reference direction	Source
Runway number	magnetic north, rounded to ten degrees	EASA CS ADR-DSN
Wind in METAR and SPECI	true north	EASA Part-MET, MET.TR.205
Wind in the ATIS	magnetic north	SERA.9005

For an exact result, bring wind and runway to the same reference. With small magnetic variation the difference is minor; with large variation it is not.