Crosswind & Headwind Component Calculator
Crosswind and headwind component calculator. Splits wind into crosswind and headwind/tailwind from the runway heading, wind direction and speed. Educational.
Crosswind and Headwind Component Calculator
How to use the crosswind calculator
Enter the runway heading
Use the magnetic heading of the runway in use — runway 09 is 090°, runway 27 is 270°, and so on. Choose the end you'll actually land or depart on.
Enter the wind
Type the direction the wind is coming from and its speed in knots. Make sure the wind direction and runway heading are referenced the same way (both magnetic for tower-reported wind).
Add the gust (optional)
If the wind is gusting, enter the gust speed too. The calculator shows the crosswind at the gust so you can compare it with your aircraft's demonstrated crosswind.
Read the components
You get the crosswind across the runway, the headwind (or tailwind) along it, and the wind angle. Compare against your aircraft limits and your own currency — the decision is yours.
Wind components — splitting the wind across and along the runway
Trigonometry on the runway
Wind almost never blows straight down the runway, so pilots resolve it into two parts: the headwind component, which acts along the runway (helping on takeoff and landing by reducing ground speed), and the crosswind component, which acts across it (pushing the aircraft sideways and demanding correction). The split is pure trigonometry. Take the angle between the wind direction and the runway heading; the crosswind component is the wind speed multiplied by the sine of that angle, and the headwind component is the wind speed multiplied by the cosine. When the wind is straight down the runway the angle is zero, so it's all headwind and no crosswind; at 90° it's all crosswind; and at angles beyond 90° the cosine goes negative, meaning a tailwind. A handy mental shortcut follows from the sine values: a wind 30° off the runway gives a crosswind of about half the wind speed, 45° gives about 70%, and 60° gives about 87%.
These components matter because aircraft have limits. Every aeroplane has a "maximum demonstrated crosswind component" — not a legal limit but the strongest crosswind a test pilot showed was controllable — and pilots set personal limits below it based on currency and conditions. The headwind component, meanwhile, shortens the ground roll and steepens the approach path over the ground, while a tailwind does the opposite and is usually restricted to a few knots. Gusts complicate the picture: a runway with a steady crosswind within limits can briefly exceed them in a gust, which is why the gust crosswind is worth checking too.
"Wind 30° off the runway is half crosswind; at 45° it's about 70%, at 60° nearly 90%. The sharper the angle, the more the wind tries to push you sideways instead of slowing you down."
Using the numbers safely
The arithmetic is exact, but a few practical points keep it honest. The wind direction and the runway heading must be expressed the same way: control towers report wind in degrees magnetic to match runway numbers, but automated and recorded weather (METARs) report it in degrees true, so mixing them introduces an error equal to the local magnetic variation. The reported wind is also an average — real wind shifts in direction and strength, and the gust value can briefly raise the crosswind well above the steady figure. The demonstrated crosswind in the handbook was achieved by a skilled test pilot on a dry runway; a wet or contaminated surface, a tired or less-current pilot, or a heavy aircraft all argue for a lower personal limit. And the components say nothing about other hazards such as wind shear, turbulence, or a gusting tailwind on a short runway. Treat this calculator as an educational aid that helps you understand and anticipate the wind, not as authority to attempt a landing near your limits. The go-around or diversion decision belongs to the pilot, using current official weather, the aircraft's approved limits, and honest self-assessment.
10 Facts About Wind Components
Crosswind = wind speed × sin(angle).
Headwind = wind speed × cos(angle).
Beyond 90° the headwind becomes a tailwind.
30° off ≈ half crosswind; 45° ≈ 70%; 60° ≈ 87%.
Runway 09 = heading 090°.
"Max demonstrated crosswind" is not a legal limit.
Tower wind is magnetic; METAR wind is true.
A headwind shortens the ground roll.
Gusts can briefly exceed the steady crosswind.
Set a personal limit below the demonstrated value.
Frequently asked questions
Take the angle between the wind direction and the runway heading, then multiply the wind speed by the sine of that angle. The headwind component is the wind speed times the cosine of the angle. For example, a 20-knot wind 30° off the runway gives a crosswind of 20 × sin30° = 10 knots and a headwind of 20 × cos30° ≈ 17 knots. The calculator does this and also tells you which side the crosswind is from.
The magnetic heading of the runway you'll use, which is the runway number times ten: runway 09 is 090°, runway 18 is 180°, runway 27 is 270°. Choose the correct end — runway 09 and runway 27 are the same strip in opposite directions, and the wind components differ completely between them. The calculator expects the heading in degrees, so enter 090 rather than 9.
It's the strongest crosswind component a test pilot demonstrated was controllable during certification, published in the aircraft handbook. Importantly, for most light aircraft it is not a legal limit — you may legally attempt more — but exceeding it means going beyond what was shown to be manageable, which is rarely wise. Pilots typically set a personal crosswind limit below the demonstrated value, adjusted down for wet runways, gusts, and reduced currency.
Because runway numbers are magnetic, and the wind must be referenced the same way to compute the angle correctly. Control towers and ATIS report wind in degrees magnetic, so it lines up with the runway directly. But written and automated reports (METARs) give wind in degrees true. If you mix a true wind direction with a magnetic runway heading, your angle is off by the local magnetic variation — which can meaningfully change the crosswind. Convert so both are on the same reference.
They come from the sine of common angles. At 30° off the runway the crosswind is about half the wind speed (sin30° = 0.5); at 45° it's about 70% (sin45° ≈ 0.71); at 60° about 87% (sin60° ≈ 0.87); and at 90° it's the full wind speed. Many pilots memorise these to estimate crosswind in their head: a 20-knot wind 45° off gives roughly 14 knots of crosswind. The calculator gives the exact figure, but the rules of thumb are handy in the cockpit.
Because the steady wind can be within your limit while a gust briefly pushes the crosswind over it, exactly when you're slow and close to the ground. Computing the crosswind at the gust speed shows the worst case you might have to control. Many pilots plan for the gust, not the average, when wind is variable. Enter the gust value and the calculator gives the gust crosswind alongside the steady one so you can judge the margin.
When the wind is blowing more than 90° from the runway heading, the along-runway component points the same way you're travelling — a tailwind. It increases ground speed, lengthening the takeoff and landing roll and flattening the approach over the ground, all of which reduce safety margins. Aircraft and operators usually restrict tailwind takeoffs and landings to a small value (often around 10 knots). The calculator shows a negative "head/tailwind" value to flag a tailwind so you can choose a more favourable runway.
No. It gives the wind components, but the decision to land, take off, choose a runway, or divert is the pilot's, made from current official weather, the aircraft's approved limits, runway condition, and an honest assessment of your own currency. The numbers don't capture wind shear, turbulence, or how the aircraft actually feels. Use the tool to understand and anticipate the wind; use airmanship to decide.
Yes — enter any runway heading from 0 to 360° and any wind direction and speed, and it resolves the components. It works the same for gliders, microlights, or large aircraft, since the trigonometry is universal; only the limits differ. Just keep the wind and runway on the same reference, and remember the reported wind is an average. The result is an educational estimate to inform, not replace, your operational decision.
No. The values you enter are processed entirely in your browser. Nothing is sent to a server, stored, or shared, and no account is required. The calculation runs on your device only.
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