Crosswind calculator

What this calculator shows

The crosswind component is the part of the reported wind that blows across the runway. The remaining part acts along the runway and is shown as a headwind or tailwind. All values are calculated in knots and rounded to one decimal place.

The wind angle matters more than the wind speed alone. A 20 kt wind blowing 30° off the runway heading produces about 10 kt of crosswind, while the same wind at 90° produces the full 20 kt. Two airports reporting the same wind speed can demand very different amounts of crosswind correction depending on which runway is in use.

How to use the calculator

Enter three values and the results update as you type. The page URL mirrors the inputs, so a configured calculation can be bookmarked or shared.

Runway heading. The magnetic heading of the runway in use, 0 to 360. Use the runway number multiplied by ten, so runway 27 is 270. Parallel runways such as 17L and 17R share the same heading for this purpose.

Wind direction. The direction the wind is coming from, 0 to 360. ATIS, AWOS, tower reports, and METAR observations all report a from direction. Do not enter the direction the wind is blowing toward.

Wind speed. Sustained wind speed in knots. For gusty conditions, run the calculation once with the sustained speed and once with the gust speed to see the spread of possible components.

How the calculation works

The calculator finds the smallest angle between the runway heading and the wind direction. The crosswind component equals the wind speed multiplied by the sine of that angle, and the longitudinal component equals the wind speed multiplied by the cosine.

crosswind = wind speed × sin(angle)

longitudinal = wind speed × cos(angle)

The sign of each result determines the label. A positive sine puts the crosswind from the right and a negative sine puts it from the left. A positive cosine is a headwind and a negative cosine is a tailwind.

Example calculation

Runway 270°, wind from 320° at 18 kt.

1. Angle between runway and wind: 320 - 270 = 50°.
2. Crosswind: 18 × sin(50°) ≈ 13.8 kt from the right.
3. Headwind: 18 × cos(50°) ≈ 11.6 kt.

On the same runway, a wind from 220° at 18 kt produces the same component magnitudes, but from the left.

When pilots use it

Preflight planning. Compare the reported or forecast wind against the aircraft's maximum demonstrated crosswind component. The demonstrated value in the POH is a figure the manufacturer achieved during certification testing and is not always a legal limitation, but it is the reference most pilots plan against.

Runway selection. When winds favor neither runway at an uncontrolled field, running the components for both directions shows which end is preferable and by how much.

Training. Working the calculation by hand and checking it here builds intuition for how quickly the component grows as the angle moves toward 90°.

Assumptions and limitations

This is a geometric calculation. It does not account for gusts unless you enter the gust speed, localized effects from terrain or hangars, runway contamination, aircraft weight, or aircraft-specific limitations. The output is a reference value, not an approval.

Match the directional reference on both inputs. Runway headings and ATIS or AWOS voice broadcasts are magnetic, while METAR reports use true north. The difference is the local magnetic variation, which can be large enough in some regions to change the result. Convert one value before comparing.

The wind reported at the observation point can differ from the wind over the runway, especially where terrain, water, or buildings sit near the field.

Frequently asked questions

Does the calculator account for gusts?

Only if you enter the gust speed. Running the sustained speed and the gust speed separately shows the range of crosswind you could see on short final.

Should I enter magnetic or true direction?

Keep both inputs on the same reference. Runway headings and ATIS winds are magnetic. METAR winds are reported relative to true north, so apply local magnetic variation before entering a METAR value.

What does from the right or from the left mean?

It describes which side of the aircraft the crosswind arrives from when facing down the runway in the direction of landing. A crosswind from the right pushes the aircraft left and calls for a right crosswind correction.

Is the maximum demonstrated crosswind a limitation?

Usually not. For many general aviation airplanes it is a demonstrated test value rather than a regulatory limit, unless the POH lists it under limitations. Check the limitations section of the applicable POH or AFM.

Sources and methodology

The crosswind component is defined by the FAA as the wind component at 90° to the runway longitudinal axis. The Airplane Flying Handbook includes the corresponding component chart, and this tool computes the same values with sine and cosine rather than interpolating a chart.

The FAA Airplane Flying Handbook, chapter 9 covers component charts and crosswind technique. The FAA Aviation Weather Handbook describes how wind direction is reported across observation sources.

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