RunwayCrosswind Calculator
Choose an airport and enter the wind. The calculator splits the wind into a headwind (or tailwind) component and a crosswind component for every open runway end, using runway designators from the RunwayFacts dataset (650 airports, 2,258 runway ends), and sorts the runways from most to least favourable.
Example result (shown before you change anything): London Heathrow Airport with wind 230° at 18 kt gusting 28 kt.
| Runway | Heading* | Head / tailwind | Crosswind | Gust head / tail | Gust crosswind | Length |
|---|---|---|---|---|---|---|
| 27Rbest | 270° | 13.8 kt head | 11.6 kt from left | 21.4 kt head | 18.0 kt from left | 12,799 ft |
| 27L | 270° | 13.8 kt head | 11.6 kt from left | 21.4 kt head | 18.0 kt from left | 12,001 ft |
| 09L | 090° | 13.8 kt tail | 11.6 kt from right | 21.4 kt tail | 18.0 kt from right | 12,799 ft |
| 09R | 090° | 13.8 kt tail | 11.6 kt from right | 21.4 kt tail | 18.0 kt from right | 12,001 ft |
* Heading = runway number × 10 (magnetic unless the designator ends in T). Helipads, water lanes and closed runways are excluded.
How crosswind and headwind are calculated
Take the angle θ between the wind direction and the runway heading. The wind vector then splits into two parts:
crosswind = wind speed × sin(θ) headwind = wind speed × cos(θ) (negative = tailwind) θ = wind direction − runway heading, normalised to −180°…+180°
A positive θ means the wind comes from the right of the runway centreline, a negative θ from the left. When θ is more than 90° either way, the cosine turns negative and the headwind becomes a tailwind — you are probably looking at the wrong end of the runway. Gusts are treated the same way: the calculator repeats the maths with the gust speed, because the crosswind you must be able to handle is the gusting one.
Worked example: London Heathrow Airport, runway 27L
- Runway 27L → heading 270° (magnetic). Wind 230° at 18 kt, gusting 28 kt.
- θ = 230° − 270° = -40°, so the wind is 40° off the nose, from the left.
- Crosswind = 18 × sin(40°) = 18 × 0.643 ≈ 11.6 kt from the left.
- Headwind = 18 × cos(40°) = 18 × 0.766 ≈ 13.8 kt.
- With the 28 kt gust: crosswind ≈ 18.0 kt, headwind ≈ 21.4 kt.
Pilots often estimate this mentally with the clock method: 15° off ≈ ¼ of the wind as crosswind, 30° ≈ ½, 45° ≈ ¾, 60° or more ≈ all of it. For 40° that gives roughly ⅔ × 18 ≈ 12 kt — close to the exact 11.6 kt.
Magnetic vs true wind — the classic trap
- Runway numbers are magnetic, rounded to the nearest 10° (27 = 265°–274°). A few high-latitude airports publish true headings, marked with a T suffix.
- Winds given by ATIS and the tower are magnetic, so you can compare them with the runway number directly.
- Winds in METAR and TAF reports are true. Before comparing them with a runway number, convert: magnetic = true − East variation (or + West variation). Select "True" above and enter the variation to let the calculator do it.
- Where variation is small (much of Western Europe today) the difference is minor; in places like eastern Canada or Alaska it can exceed 15°, which changes the crosswind noticeably.
Limits of this calculator
- Headings come from the runway designator, not the exact surveyed bearing, so the true alignment can differ by up to about 5° (and magnetic variation drifts over time, which is why runways get renumbered).
- Runway data is the OurAirports snapshot of 2026-09-01 (CC0). Temporary closures, NOTAMs, displaced thresholds and runway-in-use selection are not modelled.
- Your aircraft's maximum demonstrated crosswind (in the flight manual) is a tested value, not always a hard limit; operators set their own limits, which are typically lower on wet or contaminated runways. Many transport aircraft are limited to about 10 kt of tailwind — check yours.
- This page is for learning and pre-flight practice only. Do not use it for operational decisions.
Looking for runway lengths and layouts? Browse the airport directory or the longest runways. Data sources are described on the methodology page.