Crosswind calculator
Enter the runway number and the reported wind to split it into the part blowing across the runway and the part along it. The calculator tells you which side the crosswind comes from and whether you have a headwind or a tailwind.
Runs in your browser: nothing you enter is sent anywhere.
How to use
- Enter the runway number, for example 27 for runway 27.
- Enter the direction the wind blows from and its speed, as in a weather report (300° at 15 kt).
- If gusts are reported, enter the gust speed.
- Compare the crosswind with the maximum demonstrated crosswind of your aircraft.
- runway heading = runway number × 10°
- Δ = wind direction − runway heading
- crosswind = V × sin Δ (positive: from the right)
- headwind = V × cos Δ (negative: tailwind)
Speeds can be in any unit; the results come out in the same unit.
Worked example
Runway 27 (270°), wind 300° at 15 kt (the default values): Δ = 30°.
- crosswind = 15 × sin 30° = 7.5 kt from the right;
- headwind = 15 × cos 30° = 12.99, shown as 13 kt.
Runway 18 with wind 020° at 10 kt gusting 25 kt: the wind is 160° off the runway heading, so there is a tailwind of 9.4 kt and a crosswind of 3.4 kt from the left; in the gusts the tailwind reaches 23.5 kt — use runway 36 instead.
Tips
- Plan for the gusts, not the average wind: they decide how much crosswind you have to handle on short final.
- A tailwind lengthens the takeoff and landing roll noticeably; many aircraft handbooks allow only a few knots of it.
- The maximum demonstrated crosswind in the handbook is not a legal limit but the value test pilots showed to be safe; your own limit may be lower.
Frequently asked questions
How are the wind components calculated?
With the angle Δ between the wind direction and the runway heading, crosswind = wind speed × sin Δ and headwind = wind speed × cos Δ. A negative headwind is a tailwind.
How do I turn a runway number into a heading?
Multiply by ten. Runway 27 points to about 270°, runway 09 to about 090°. Runway numbers are rounded magnetic headings, so the real heading can be a few degrees off; for precise work use the published runway heading.
Should I use true or magnetic wind?
The same reference as the runway. Runway numbers are magnetic. Winds read out by the tower and the ATIS are magnetic, but winds in a written METAR or TAF are true, so in places with large magnetic variation correct the METAR wind first.
Is there a quick rule without a calculator?
A common approximation: at 30° off the runway the crosswind is about half the wind speed, at 45° about 70 %, at 60° about 90 %, and from 90° all of it. The exact factors are sin 30° = 0.5, sin 45° = 0.71 and sin 60° = 0.87.