Crosswind calculator: crosswind, headwind and tailwind for any runway
This crosswind calculator splits the reported wind into the part across the runway and the part along it – the same result the FAA crosswind component chart gives, but exact. FAA example: runway 17, wind 140° at 25 knots is 30° off the runway: 12.5 kn crosswind from the left and 21.7 kn headwind.
Example: Runway number 17 · Wind direction 140 ° · Wind speed 25 kn → Wind components: Crosswind 12.5 kn from the left, headwind 21.7 kn. Source: FAA, Pilot’s Handbook of Aeronautical Knowledge, Chapter 11 “Aircraft Performance”: Crosswind and Headwind Component Chart, Sample Problem 10 (runway 17, wind 140° at 25 kn → 22 kn headwind, 13 kn crosswind), certification at 0.2 VS0, maximum demonstrated crosswind in the AFM/POH (read 09.10.2026). Updated: .
How it is calculated
Crosswind = wind speed × sin(angle), headwind = wind speed × cos(angle). The angle is the difference between the wind direction and the runway heading (runway number × 10). The FAA Pilot’s Handbook of Aeronautical Knowledge solves the same problem with its crosswind component chart: runway 17, wind 140° at 25 knots, 30° difference – the chart shows about 22 kn headwind and 13 kn crosswind. Calculated exactly it is 21.7 kn and 12.5 kn.
Examples
| Runway | Wind | Angle | Crosswind | Head/tailwind |
|---|---|---|---|---|
| 17 | 140° / 25 kn | 30° | 12.5 kn left | 21.7 kn head |
| 27 | 240° / 20 kn | 30° | 10.0 kn left | 17.3 kn head |
| 27 | 300° / 18 kn | 30° | 9.0 kn right | 15.6 kn head |
| 36 | 045° / 20 kn | 45° | 14.1 kn right | 14.1 kn head |
| 09 | 180° / 15 kn | 90° | 15.0 kn right | 0.0 kn |
| 09 | 240° / 10 kn | 150° | 5.0 kn right | 8.7 kn tail |
With gusts, take the gust value too: 140° at 25 gusting 35 knots on runway 17 gives 17.5 kn crosswind in the gusts.
Magnetic or true wind?
Runway numbers are magnetic: according to the FAA Aeronautical Information Manual (AIM 2-3-3) the runway number is the magnetic azimuth of the centerline divided by ten. Wind in ATIS and in ASOS/AWOS radio broadcasts is also given in degrees magnetic (AIM 7-1-10), so you can enter it directly. Wind in a written METAR or TAF is referenced to true north (AIM 7-1-29) – convert it with the local magnetic variation first, otherwise the angle is off by that amount.
How much crosswind is allowed?
According to the FAA, every airplane is tested before certification in 90° crosswinds of up to 0.2 VS0 – with a power-off stall speed of 45 knots that is 9 knots. The maximum demonstrated crosswind component is published in the AFM/POH; enter it to compare. Knots to mph or km/h: knots to mph; for hot and high days see the density altitude calculator.
Frequently asked questions
How do you calculate the crosswind component?
Wind speed times the sine of the angle between wind and runway. 25 knots at 30° gives 25 × 0.5 = 12.5 kn.
How do you calculate the headwind component?
Wind speed times the cosine of the angle. 25 knots at 30° gives 21.7 kn headwind.
What is the quick rule for crosswind?
At 30° the crosswind is half the wind, at 45° about 71 %, at 60° about 87 % – exact values come from sin(angle).
How do I handle gusts?
Calculate the crosswind with the gust speed as well: 35 knots at 30° gives 17.5 kn.
What crosswind can my airplane handle?
The maximum demonstrated crosswind component is in the AFM/POH. Certification requires 0.2 VS0, e.g. 9 knots with a 45 kn stall speed.
When do I get a tailwind?
When the angle exceeds 90°. Runway 09 with wind 240° at 10 knots gives 8.7 kn tailwind and 5.0 kn crosswind.
Sources and legal basis
- FAA, Pilot’s Handbook of Aeronautical Knowledge, Chapter 11 “Aircraft Performance”: Crosswind and Headwind Component Chart, Sample Problem 10 (runway 17, wind 140° at 25 kn → 22 kn headwind, 13 kn crosswind), certification at 0.2 VS0, maximum demonstrated crosswind in the AFM/POH (read 09.10.2026)
- FAA Aeronautical Information Manual 2-3-3 “Runway Markings”: runway number = whole number nearest one-tenth of the magnetic azimuth of the centerline (read 09.10.2026)
- FAA Aeronautical Information Manual 7-1-10 (ATIS and ASOS/AWOS radio broadcasts: wind relative to magnetic north) and 7-1-29 (METAR wind “referenced to true north”) (read 09.10.2026)
- NIST SP 811, Appendix B.8 – 1 knot = 0.514 444 m/s (read 09.10.2026)
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