How to calculate crosswind and headwind components

By Zulu Calculator · Updated 19 October 2026 · Aviation

To find the crosswind on a runway, take the angle between the wind direction and the runway heading. The crosswind is the wind speed × sin(angle) and the headwind is the wind speed × cos(angle). On runway 27 with wind from 300° at 20 kt, the wind is 30° off the runway, so you get 20 × 0.5 = 10 kt of crosswind from the right and 20 × 0.866 = 17 kt of headwind.

This guide covers the formulas, the clock-face rule of thumb, gusts, true and magnetic winds, choosing the best runway, tailwinds and crosswind limits. To run your own numbers, use the crosswind calculator.

What are the headwind and crosswind components?

Any wind can be split into two parts. One runs along the runway: a headwind if it blows towards you as you take off or land, a tailwind if it blows from behind. The other runs straight across the runway: the crosswind. Each part is checked against a different figure: the crosswind against your crosswind limit, a tailwind against your tailwind limit.

Two things set the size of each part: the wind speed, and the angle between the wind and the runway. Wind direction is always where the wind blows from, so "300° at 20 kt" is a wind coming from the north-west at 20 knots.

How do you calculate the crosswind component?

angle = wind direction − runway heading
crosswind = wind speed × sin(angle)
headwind = wind speed × cos(angle)
a negative headwind is a tailwind

The runway heading is the runway number times ten: runway 27 is 270°, runway 09 is 090°. If you know the exact heading, such as 273°, use that instead. The calculator accepts either.

Take the angle as the short way round, between −180° and +180°. A positive angle means the wind is to the right of the runway heading, so the crosswind comes from the right. A negative angle means it comes from the left. Wind from 020° on runway 35 (350°) is 30° to the right, not 330° to the left.

Once the angle passes 90°, the cosine goes negative and the headwind becomes a tailwind. At exactly 90° the whole wind is crosswind and there is no headwind at all.

Crosswind and headwind by angle

This table gives the share of the wind that ends up as crosswind and as headwind at each angle, and what that means for a 20 kt wind. The calculator rounds to whole knots, as here.

Notice how fast the crosswind builds: at only 30° off, half the wind is already across the runway. The headwind falls away slowly at first and then quickly past 60°.

What is the clock method for crosswind?

The clock method is a quick mental estimate. Picture the angle off the runway as minutes on a clock face, with each 15° worth a quarter of an hour:

• 15° off: a quarter of the wind is crosswind (exact: 26%).
• 30° off: half the wind (exact: 50%).
• 45° off: three quarters of the wind (exact: 71%).
• 60° or more: all of the wind (exact: 87–100%).

It is close enough for a quick check on the ATIS. Past 60° it overstates the crosswind a little, which errs on the safe side. Use it to sense-check a figure, and the formula when the answer is close to your limit.

How do gusts affect the crosswind?

Work out the components a second time with the gust speed in place of the steady wind. The angle stays the same, so the crosswind in the gusts is simply the gust speed × sin(angle). Compare the gust crosswind, not the steady one, with your limit.

Gusts also feed the approach speed. A common technique, not a rule for every aircraft, adds half the steady headwind plus the whole gust increment (gust minus steady wind), capped at 20 kt. A tailwind adds nothing for the half-headwind part. Your aircraft's handbook or your operator may use a different method or none, and that one wins.

approach speed add = half the steady headwind + (gust − steady wind), up to 20 kt

Is the wind in a METAR true or magnetic?

Runway numbers are magnetic. Winds in a METAR or TAF are given in degrees true, while ATIS and tower winds are magnetic. Where magnetic variation is large, convert a METAR wind before you compare it with the runway:

magnetic wind = true wind − east variation
magnetic wind = true wind + west variation

The rhyme is "east is least, west is best". A METAR wind of 310° with 10° east variation is 300° magnetic. With 10° west variation it would be 320° magnetic. If you paste a METAR wind group such as 31020G30KT 280V340 into the calculator, it reads the direction, speed, gust and variable range for you; the METAR and TAF decoder reads the whole report.

The variable range in a METAR (for example 280V340) is clockwise from the first direction to the second, and is in the same reference as the main wind, so correct it by the same variation. A wind reported as VRB has no fixed direction: plan for the full speed as crosswind.

Worked examples

Example 1: runway 27, wind 300° at 20 kt gusting 30 kt

• Angle: 300 − 270 = 30°, to the right.
• Crosswind: 20 × sin 30° = 20 × 0.5 = 10 kt from the right.
• Headwind: 20 × cos 30° = 20 × 0.866 = 17.32, so 17 kt.
• Crosswind in the gusts: 30 × 0.5 = 15 kt. Headwind in the gusts: 30 × 0.866 = 25.98, so 26 kt.
• Other end, runway 09 (090°): the wind is 150° off, so the headwind is 20 × cos 150° = 20 × −0.866 = 17 kt of tailwind, with 10 kt of crosswind from the left.
• Approach speed add: half of 17.32 is 8.66, plus the 10 kt gust increment, gives 18.66, so about 19 kt (under the 20 kt cap).

With a 15 kt crosswind limit, this runway is exactly at the limit in the gusts, even though the steady wind looks comfortable.

Example 2: a METAR wind with variation and a variable range

The METAR reads 31020G30KT 280V340, the local variation is 10° east, and you are landing on runway 27.

• Convert to magnetic: 310 − 10 = 300°. The range becomes 280 − 10 = 270° to 340 − 10 = 330°.
• Main wind: as in example 1, 10 kt of crosswind steady and 15 kt in the gusts, with a 17 kt headwind.
• Worst case in the range: at 330° the wind is 60° off the runway. In the gusts that is 30 × sin 60° = 30 × 0.866 = 25.98, so 26 kt of crosswind. In the steady wind it is 20 × 0.866 = 17 kt.
• Headwind at that worst point: 30 × cos 60° = 30 × 0.5 = 15 kt in the gusts, so the range never turns into a tailwind here.

Had you used 310° straight from the METAR, the angle would be 40° and you would get 20 × 0.643 = 12.86, so 13 kt of steady crosswind instead of 10 kt. Small here, but at airports with large variation the error grows.

Example 3: picking the best runway

An airport has runways 09/27 and 04/22. The ATIS gives wind 120° at 12 kt. Work out every runway end and pick the one with the largest headwind:

Runway 09 wins: the most headwind and the least crosswind. Runway 27 has the same crosswind but a 10 kt tailwind (10.39 kt before rounding), which is at or over the 10 kt tailwind limit many aircraft publish. Runway 04 is nearly a pure crosswind. In Advanced mode, the calculator ranks every runway end like this when you list the runways.

Which runway should I use?

Generally the one most into wind: the runway end whose heading is closest to the wind direction. It gives the most headwind and, for the same wind, the least crosswind. The rule the calculator uses is largest headwind first, then smallest crosswind if two ends tie.

Each runway has two ends with headings 180° apart (09 and 27, 04L and 22R), and the headwind on one is the tailwind on the other. The crosswind is the same size on both ends but from opposite sides. On parallel runways the letters swap too: the other end of 09L is 27R.

What about tailwind?

A tailwind is any wind more than 90° off the runway heading. Many aircraft have a published tailwind limit, often 10 kt for take-off and landing. Check the tailwind in the gusts and across any variable range too: a wind that varies can swing from a light headwind into a tailwind. If the tailwind on your runway is over the limit, the other end of the same runway will have a headwind of the same size.

Is the maximum demonstrated crosswind a limit?

The maximum demonstrated crosswind in a light aircraft's handbook is a tested figure. It is not always a hard limit, but it is a sensible personal ceiling. Where the handbook or your operator gives a firm crosswind or tailwind limit, that is the figure to plan against. Enter your limit in the calculator's Advanced mode and it shows the crosswind as a percentage of it and warns when the worst case, including gusts and any variable range, is over.

Common mistakes

• Using a METAR wind against runway numbers without converting. METAR and TAF winds are true; runways, ATIS and tower winds are magnetic.
• Checking only the steady wind. Compare the gust crosswind with your limit. In example 1 it is 15 kt, not 10 kt.
• Ignoring the variable range. A 280V340 group can turn a 10 kt crosswind into 26 kt in the gusts.
• Reading the wind as where it blows to. Wind direction is where it comes from.
• Missing a tailwind. Past 90° off, the headwind turns negative. If the answer looks like a "negative headwind", it is a tailwind.
• Trusting the clock rule near your limit. It is an estimate. When the crosswind is close to the limit, use sin(angle).
• Treating a VRB wind as calm. With no fixed direction, plan for the full speed as crosswind.

What if the crosswind is over my limit?

Look at the other runway ends first: one may be more into wind. If none is within your limits, including the gusts and the variable range, you should not take off or land on it in that wind. This guide is for study, planning and cross-checking. Your aircraft flight manual (AFM or POH), your operator's procedures and the latest reported wind always come first.

The same sine and cosine split is used en route. To turn a forecast wind into a heading and ground speed for a leg, use the wind triangle calculator.

Quick summary

• Angle = wind direction − runway heading, taken the short way round.
• Crosswind = wind × sin(angle); headwind = wind × cos(angle).
• Clock rule: 15° = ¼, 30° = ½, 45° = ¾, 60° or more = all of the wind.
• Work out the gust crosswind and compare that with your limit.
• METAR and TAF winds are true; ATIS, tower winds and runways are magnetic. East is least, west is best.
• Best runway: the end with the most headwind. More than 90° off means a tailwind.
• The handbook and your operator's limits always win.

Work out your own runway with the crosswind calculator, decode the report with the METAR and TAF decoder, or plan a leg with the wind triangle calculator. Flying in winter? See cold temperature altimeter correction explained.

Formulas and rules as used by our crosswind calculator (checked 9 October 2026; examples run 19 October 2026).

This guide explains the rules in plain English for planning. It is not legal, financial or flight-operations advice; check your contract, the official source linked above, your employer or your operator.