Crosswind calculator
Enter the runway and the wind from the METAR or ATIS – you get headwind or tailwind and crosswind for both runway directions, including gusts, the best runway and a comparison with the demonstrated crosswind of your aircraft.
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How the components are calculated
The angle between wind direction and runway heading decides how the wind splits. Crosswind = wind speed × sin(angle), headwind = wind speed × cos(angle). With a wind of 240° at 15 kt on runway 28 (280°) the angle is 40°: 11.5 kt headwind and 9.6 kt crosswind from the left. In the gusts of 25 kt it is 16 kt crosswind.
Runway numbers are magnetic headings rounded to 10°; enter three digits (e.g. 283) if you know the exact heading. The METAR reports the wind relative to true north, ATIS and tower relative to magnetic north. In Switzerland the difference is only about 3°, elsewhere it can be much larger.
Rule of thumb: the clock method
Without a calculator, think of the angle as minutes on a clock: 15° ≈ a quarter of the wind speed as crosswind, 30° ≈ half, 45° ≈ three quarters, 60° and more ≈ the full wind. The exact values are sin 15° = 26 %, sin 30° = 50 %, sin 45° = 71 %, sin 60° = 87 %.
The headwind follows the cosine: at 30° you keep 87 % of the wind as headwind, at 60° only half. Beyond 90° it becomes a tailwind – Cessna POHs, for example, add 10 % to the takeoff distance for every 2 kt of tailwind.
Demonstrated crosswind
The POH lists the maximum demonstrated crosswind component, for example 15 kt for the Cessna 172 or 17 kt for the Piper PA-28. In most POHs it is not a limitation but the value tested during certification. Your personal limit depends on experience, recent practice, runway width and gusts – many instructors recommend staying well below the demonstrated value in gusty conditions.
Choose your aircraft in the list to compare: the calculator marks the result green, orange (above 80 %) or red (above the demonstrated value), using the gust value when gusts are reported.
Frequently asked questions
How do I calculate the crosswind component?
Crosswind = wind speed × sine of the angle between wind and runway. Example: 20 kt at 30° gives 10 kt crosswind. The headwind is wind speed × cosine of the angle.
Should I use the gust value?
Check both. The steady wind gives the typical component, the gust value the worst case. Many pilots plan the crosswind with the full gust and add half the gust increment to the approach speed, as many training manuals recommend.
Is the METAR wind true or magnetic?
METAR and TAF give the wind direction relative to true north. ATIS and the tower give it relative to magnetic north, like the runway numbers. In central Europe the difference is only a few degrees.
What is the maximum demonstrated crosswind?
The highest crosswind component tested during certification, listed in the POH. For most light aircraft it is 12–20 kt and not a formal limitation – but a good guide for personal limits.
Which runway should I use?
Usually the one with the most headwind; the calculator marks it as the best runway. Also consider runway length, slope, obstacles and the active runway at the aerodrome.
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