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crosswind calculator

Live wind against every runway at any airport, drawn as well as counted, with magnetic and true kept apart.

Runways and live wind come from the NOAA feed.

Fetching airport data

Why magnetic and true both matter here

Runway numbers are magnetic: runway 27 points roughly 270° magnetic. The wind in a written METAR is true, while the wind read to you by ATIS or the tower is already magnetic. Mixing the two puts your crosswind out by the local variation, which is a few knots in the UK and a great deal more at high latitudes. In airport lookup this tool works entirely in true, using each runway’s surveyed alignment, then converts to magnetic only for display.

The trigonometry itself is one angle: with θ the difference between the wind and the runway, crosswind = wind speed × sin θ and headwind = wind speed × cos θ. That is exactly what the plan view draws: the wind arrow is the hypotenuse, and the two legs are the components. At 30° off, the crosswind is half the wind; at 60° off it is nearly all of it.

Data: NOAA Aviation Weather Center, refreshed on demand. For training and reference only: always use an approved briefing source for operational decisions, and respect your aircraft’s demonstrated crosswind and your own currency.

The crosswind component is the wind speed multiplied by the sine of the angle between the wind and the runway. Everything difficult about it is bookkeeping: runway numbers are magnetic, written METAR winds are true, and gusts matter more than the mean. This calculator does all three properly for every runway at an airport at once.

Key takeaways

  • Crosswind = wind speed × sin θ, headwind = wind speed × cos θ, where θ is the angle between the wind and the runway.
  • The quick mental version: 30° off is a half, 45° is seven tenths, 60° is nine tenths, and 90° is all of it.
  • Runway numbers are magnetic. A written METAR wind is true. An ATIS or tower wind is magnetic.
  • Plan on the gust, not the mean, and on the worst case inside a variable range.
  • The demonstrated crosswind is usually not a limitation. Your own limit is the one that keeps you alive, and it should be a number you decided on the ground.

Working the component out

Put the wind and the runway on the same compass. The angle between them is all the calculation needs: the component across the runway is the wind speed multiplied by the sine of that angle, and the component along it is the wind speed multiplied by the cosine. A wind straight down the runway is all headwind and no crosswind; a wind straight across is all crosswind and no headwind.

Because the sine curve is steep near zero and flat near ninety, the first thirty degrees cost you the most. A 20 knot wind 10° off the runway is a 3 knot crosswind. The same wind 30° off is 10 knots, and 60° off it is 17 knots. Beyond about 60° there is very little left to gain from a better-aligned runway, which is worth knowing when you are choosing between two of them.

Magnetic, true, and the mistake almost everybody makes

A runway is numbered to the nearest ten degrees of its magnetic alignment. The wind in a written METAR is referenced to true north. The wind read out on the ATIS or by the tower has already been converted to magnetic for you. Compare a written METAR wind against a runway number and your answer is wrong by the local magnetic variation: small in southern England, several degrees across most of the United States, and very large indeed at high latitudes.

In airport lookup this tool sidesteps the problem entirely. It uses each runway’s surveyed true alignment against the METAR’s true wind, so no conversion happens before the trigonometry, and it converts to magnetic only to print the number you will hear on the radio. In manual mode you tell it which reference your wind figure is in, and it converts once, in the right direction.

Gusts, variable winds and the worst case

A crosswind you can hold in the mean wind is not the same as one you can hold in the gust. If a METAR reports 25 knots gusting 38, the flare will be flown in 38. This calculator shows the gust component beside the steady one and bands each runway against the worst case the report allows.

A variable group, the 260V320 that follows the main wind, is treated the same way: the wind may sit anywhere inside that arc, so the tool sweeps it and reports the largest crosswind it finds. A wind reported as VRB has no usable direction at all, so the honest answer is the full speed straight across, on every runway.

Demonstrated crosswind is not usually a limit

The figure in the flight manual is the strongest crosswind in which a test pilot landed the aircraft during certification. For most light aircraft it is a demonstration, not a limitation, and the aircraft is capable of more. That is the wrong conclusion to draw from it. The relevant limit is your own, on that day, in that aeroplane, at the end of that flight, and it should be a figure you set on the ground rather than one you discover on short final.

Set yours in the box above. Every runway is then coloured against it: green below two thirds, amber approaching it, red beyond. A few aircraft do publish a genuine crosswind limitation rather than a demonstrated figure, and where they do it is binding, so check the limitations section rather than assuming.

Frequently asked questions

How do you calculate the crosswind component?

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 multiplied by the cosine of the same angle. At 30 degrees off the runway the crosswind is half the wind speed, at 45 degrees about seven tenths, at 60 degrees about nine tenths, and at 90 degrees the whole of it.

Is the runway heading magnetic or true?

Magnetic. A runway is numbered to the nearest ten degrees of its magnetic alignment, so runway 27 points roughly 270 degrees magnetic. This matters because the wind in a written METAR is referenced to true north, while the wind read to you by ATIS or the tower is already magnetic. Comparing a true wind against a magnetic runway puts the answer out by the local variation.

Why does this calculator show two headings for each runway?

Because the two references answer different questions. The magnetic figure is the number painted on the runway and the one you use on the radio. The true figure is the surveyed alignment, and it is the one the calculator does its trigonometry against, since the METAR wind is also true. Working entirely in true means no conversion error can creep into the components.

What is the maximum demonstrated crosswind component?

It is the strongest crosswind in which the aircraft was landed during certification testing. In most aircraft it is not a legal limitation, only a figure a test pilot achieved on the day, and your own limit should usually sit below it. Check your flight manual: some aircraft do publish a genuine crosswind limitation, and then it is binding.

Should I use the gust or the steady wind for my crosswind limit?

Plan on the gust. A gust of 25 knots across the runway is what you will have to fly in the flare, even if the mean is 15. This calculator shows both, and colours the runway against the worst case your reported wind can produce, including anywhere inside a reported variable range.

What counts as a strong crosswind for a student pilot?

That is a personal limit rather than a number anyone else can set. Most students start with something modest, perhaps eight to ten knots, and raise it deliberately with an instructor rather than by accident on a windy day. Set your figure in the box above and the tool will colour every runway against it.

Can I use a tailwind runway if the crosswind is lower?

Only within your aircraft's published tailwind limit, and after checking the performance figures, because a tailwind lengthens both take-off and landing distances significantly. The calculator flags any runway end where the component is a tailwind. At a controlled field the runway in use is the tower's decision, not yours.

Where does the wind data come from?

The latest METAR published by the NOAA Aviation Weather Center, fetched when you look the airport up. Runway alignments and elevations come from the same feed. It is a briefing aid, not an approved source: brief properly before you fly.

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