Crosswind Calculator: Headwind, Crosswind and Tailwind
Enter a runway and the wind, and the calculator gives the crosswind, headwind or tailwind component, in the gusts too. It converts a METAR or TAF wind (true) to magnetic for you, shows the other end of the runway, and checks the result against the limits you enter.
Crosswind calculator
Enter a runway and a wind to see the components.
Method: crosswind = wind speed × sine of the angle between the wind and the runway; headwind = wind speed × cosine of that angle (FAA Airplane Flying Handbook, FAA-H-8083-3C). Wind references: ICAO Annex 3, Meteorological Service for International Air Navigation. Demonstrated crosswind: 14 CFR 25.237 and EASA CS 25.237.
How the components are worked out
Take the angle between the wind direction and the runway heading. The part of the wind blowing along the runway is the wind speed times the cosine of that angle; the part blowing across it is the wind speed times the sine. A wind straight down the runway is all headwind; a wind at 90° is all crosswind; a wind from behind the wing is a tailwind.
Worked example: runway 27 (270°) and a wind of 240° at 15 kt. The wind is 30° off the runway, from the left. Crosswind: 15 × sin 30° = 7.5 kt from the left. Headwind: 15 × cos 30° = 13 kt. On runway 09, the other end, the same wind gives a 13 kt tailwind and 7.5 kt from the right.
| Angle off the runway | Crosswind (sine) | Headwind (cosine) |
|---|---|---|
| 10° | 0.17 of the wind | 0.98 |
| 20° | 0.34 | 0.94 |
| 30° | 0.50 | 0.87 |
| 45° | 0.71 | 0.71 |
| 60° | 0.87 | 0.50 |
| 90° | 1.00 | 0 |
A runway number is the runway's magnetic heading rounded to the nearest 10°, so runway 27 can point anywhere from about 265° to 274°. For a close call, use the exact heading from the aerodrome chart. In a few regions where the compass is unreliable, such as the far north of Canada, runways are numbered by true heading instead.
True or magnetic: METAR against ATIS
The wind in a METAR, SPECI or TAF is given in degrees true, averaged over 10 minutes. The wind that the tower gives you for take-off and landing, and the one on the ATIS, is in degrees magnetic, averaged over 2 minutes, so it can be compared directly with the runway heading. The runway heading is magnetic too.
To compare a METAR wind with a runway, convert it to magnetic with the local variation: subtract an easterly variation, add a westerly one (“east is least, west is best”). With 2° E, a METAR wind of 240° true is 238° magnetic. In most of Europe the variation is only a few degrees and changes little, but in parts of North America it passes 15°, enough to change the crosswind by a quarter of the wind speed. Choose A METAR or TAF (true) above and enter the variation, and the calculator converts it.
The v1prep METAR and TAF decoder reads the live reports for any airport in plain English, and the Flight Briefing works out the runway components at both ends of your flight for your times.
Gusts and a variable wind
A reported gust (25015G28KT) means the wind reaches 28 kt for short periods. Enter it, and the calculator gives the components in the gusts as well as in the mean wind. Whether your limit is compared with the mean wind or with the gusts is written in your manuals; Airbus, for example, gives its maximum demonstrated crosswind “gust included”. When in doubt, use the gust value.
A variable wind (VRB05KT), or a direction that swings (240V300), has no single angle. Work out the components for both ends of the range, or take the worst case: all of it across the runway, or all of it from behind.
Crosswind and tailwind limits
When a large aeroplane is certified, the manufacturer must demonstrate that take-off and landing are safe on a dry runway with a 90° crosswind of at least 20 kt or 0.2 VSR0, whichever is greater; it need not demonstrate more than 25 kt (14 CFR 25.237 and CS 25.237). Most airliners have demonstrated much more. The flight manual gives this maximum demonstrated crosswind, which for many types is a figure that was tested rather than a hard limitation. The limit you fly to is your operator's: usually lower on a wet or contaminated runway, lower on a narrow runway, lower with some systems inoperative, and sometimes lower for a new captain or first officer.
Most airliners are certified for a tailwind of 10 kt at take-off and landing, and some types for 15 kt with extra conditions. A tailwind lengthens the take-off and landing distances much more than a headwind of the same strength shortens them, and the certified performance data count no more than 50 % of a reported headwind and at least 150 % of a reported tailwind (14 CFR and CS 25.105 and 25.125). The rules and the techniques are in the Library: wind components and crosswind limits and landing technique and crosswind operations.
The clock method, in your head
Think of the angle between the wind and the runway as minutes on a clock face. 15 minutes is a quarter of the hour, so a wind 15° off gives about a quarter of its speed as crosswind; 30°, about half; 45°, about three quarters; and from 60°, nearly all of it. The sines are 0.26, 0.50, 0.71 and 0.87, so the method is close, and it errs on the safe side from 45°. The result box above gives the clock-method figure next to the exact one.
Frequently asked questions
How do you calculate the crosswind component? Multiply the wind speed by the sine of the angle between the wind direction and the runway heading. The headwind (or tailwind) component is the wind speed times the cosine of the same angle. For runway 27 and a wind of 240° at 15 kt, the angle is 30°: the crosswind is 7.5 kt from the left and the headwind 13 kt.
Is the wind in a METAR true or magnetic? True. The wind in a METAR, SPECI or TAF is in degrees true, averaged over 10 minutes. The wind the tower and the ATIS give for take-off and landing is in degrees magnetic, averaged over 2 minutes, like the runway heading. To compare a METAR wind with a runway, subtract an easterly variation or add a westerly one.
Should I use the gust or the mean wind for the crosswind limit? Your aircraft's flight manual and your operator's manuals say which. Airbus, for example, gives the maximum demonstrated crosswind gust included. When in doubt, use the gust: the calculator shows the components for both.
What is the maximum demonstrated crosswind? The crosswind the manufacturer showed to be safe during certification. For a large aeroplane, 14 CFR and CS 25.237 require a 90° crosswind on a dry runway of at least 20 kt or 0.2 VSR0, whichever is greater, but no more than 25 kt has to be demonstrated. The figure is in the flight manual, and for many types it is not a hard limitation; your operator's crosswind limits, usually lower on wet or contaminated runways, are the ones you fly to.
What is the clock method for crosswind? A mental shortcut. Treat the angle between the wind and the runway as minutes on a clock: 15° gives about a quarter of the wind speed as crosswind, 30° about half, 45° about three quarters, and 60° or more nearly all of it.
Know it before the examiner asks
Wind components, the standard atmosphere and performance come up in the ATPL theory exams, the FAA written tests and airline interviews. v1prep has 16,000+ questions with every answer cited to its source.
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