What this calculator does
A single wind reading, given as a speed and a compass direction, rarely lines up exactly with a runway. Part of that wind pushes across the runway (the crosswind component) and part of it pushes along the runway, either into the aircraft (a headwind) or behind it (a tailwind). Both figures matter for deciding whether a landing or takeoff is within the aircraft’s and pilot’s limits.
The two components come from simple trigonometry on the angle between the runway heading and the wind direction: the crosswind uses the sine of that angle, the along-runway component uses the cosine. This calculator takes runway heading and wind direction as compass degrees, the way they are reported in a METAR or by ATC, rather than as a pre-computed angle.
The formula
Take the difference between runway heading and wind direction. Crosswind component is wind speed times the sine of that difference; the along-runway component is wind speed times the cosine of that difference, positive for a headwind and negative for a tailwind.
| Term | Meaning |
|---|---|
| Runway heading | The compass direction the runway points, e.g. runway 28 points at roughly 280°. |
| Wind direction | The compass direction the wind is blowing from, as reported by ATC or a METAR. |
| Crosswind component | The part of the wind blowing across the runway rather than along it. |
| Headwind/tailwind component | The part of the wind blowing along the runway; a headwind slows groundspeed on takeoff and landing roll, a tailwind increases it. |
The inputs explained
| Field | What to enter |
|---|---|
| Wind speed (knots) | The reported wind speed. |
| Wind direction (compass degrees, from) (°) | The compass direction the wind is coming from, in degrees. |
| Runway heading (compass degrees) (°) | The compass heading of the runway being used, in degrees. |
When to use it
Checking a crosswind limit before landing
Comparing the calculated crosswind component against the aircraft’s demonstrated crosswind limit, or your own personal limit, is a standard pre-landing check.
Choosing between two runways
At an airport with more than one usable runway, working out the crosswind component for each shows which one gives the more favourable wind for the conditions.
Understanding a sudden tailwind on landing
A wind direction shift during an approach can turn what looked like a headwind into a tailwind component, which lengthens the landing roll unexpectedly.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the crosswind component changes with the angle between wind and runway
A fixed wind speed and runway heading, across a range of wind directions.
| Wind direction | Crosswind component | Headwind/tailwind component |
|---|---|---|
| 280° | 0.0 kt | 18.0 kt |
| 260° | 6.2 kt | 16.9 kt |
| 250° | 9.0 kt | 15.6 kt |
| 230° | 13.8 kt | 11.6 kt |
| 215° | 16.3 kt | 7.6 kt |
| 195° | 17.9 kt | 1.6 kt |
Questions
What does a negative headwind figure mean?
It means the along-runway component is actually a tailwind rather than a headwind: the wind is pushing from behind rather than from ahead. This calculator always labels the result as either a headwind or a tailwind rather than leaving a bare negative number.
Do I use the wind direction as reported, or the direction it is blowing towards?
Wind direction in aviation is always reported as the direction the wind is coming from, which is also what this calculator expects. Runway headings are reported as the direction the runway points, i.e. the direction an aircraft using it is heading.
Why do larger angles between wind and runway matter so much for crosswind?
Because the crosswind component depends on the sine of that angle, which rises quickly as the angle increases from zero and peaks at a full 90° crosswind, where all of the wind speed becomes crosswind and none of it is headwind or tailwind.
Is this the same as the general crosswind calculator elsewhere on this site?
It solves the same underlying trigonometry, but is framed specifically around compass-degree runway headings and wind directions as used in aviation, rather than a generic angle-between-two-directions input.
For the true airspeed feeding into your approach or departure planning, see the true airspeed estimate calculator. To check density altitude on the same day, see the density altitude calculator.