Crosswind calculator
Enter the wind direction, the wind speed and the runway. You get the crosswind and which side it blows from, and the headwind or tailwind, in knots, for the steady wind and for a gust. It is free and runs in your browser.
Wind (blowing FROM)
Crosswind (steady)
9 kt
Blowing from the RIGHT
Headwind
16 kt
Component along the runway
Crosswind in the gust
13 kt
Peak from the RIGHT · 8 kt above the steady wind
Best runway into this wind
RWY 30
0 kt crosswind · 18 kt headwind
Wind triangle: headwind = wind × cos Δ, crosswind = wind × sin Δ, where Δ is the wind direction minus the runway heading. Enter the wind direction in the same kind of degrees as the runway (magnetic). Same computed engine as the app.
Training and planning aid only — not for primary flight operations. It computes and compares against limits you set; it never advises. Always verify wind, weather, and aircraft performance with official sources and your aircraft's POH.
What the answers mean
The wind is split into two parts. The headwind blows along the runway, into your nose; the crosswind blows across it. The Airplane Flying Handbook describes the same split: the natural wind
It has a headwind component acting along the airplane’s ground track and a crosswind component acting 90° to its track. [AFH p. 9-18]
When the headwind comes out negative it is a tailwind: the wind is blowing from behind. The calculator names the side the crosswind comes from, left or right, as seen looking down the runway in the direction you are going.
What to type
Wind direction is the direction the wind blows from, in degrees, 0 to 360. Speed and gust are in knots. Add a gust only if there is one; leave the gust box empty or at or below the steady speed and it is ignored.
Runway is its number, such as 27. The calculator uses the number times ten as the runway heading, so runway 27 is 270°. The FAA says what the number is:
Runways are identified by numbers that indicate the nearest 10-degree increment of the azimuth of the runway centerline. For example, where the magnetic azimuth is 183 degrees, the runway designation would be 18; for a magnetic azimuth of 87 degrees, the runway designation would be 9. [AIM 4-3-6 a]
So the real centerline can differ from the number times ten by up to 5°. Runway numbers are magnetic, so type the wind in magnetic degrees too. A METAR’s wind is not; see METAR wind and your runway.
Best runway
The calculator also ranks all 36 runway headings for your wind. Any heading with a tailwind goes below every heading without one; within each group the one with the smaller crosswind is first, then the one with more headwind. That is the app’s rule for “best”. It ranks headings, not the runways at a particular airport, and it is not a recommendation.
- The formula. Crosswind = wind speed × sin(angle), headwind = wind speed × cos(angle).
- Crosswind chart. Knots of crosswind and headwind for wind angles 0° to 90° and speeds 10 to 30 knots.
- Crosswind with gusts. The crosswind in the gust, worked, and where your own limits fit.
- METAR wind and runways. A METAR wind is true; runways and the tower’s wind are magnetic. What that does to the answer.
- Worked examples. Nine winds worked by hand, step by step.
- FAQ. Short answers, and what the calculator leaves out.
Take it to the airport in Crosswind Calculator
For iPhone and iPad. Works offline.
This calculator is the app’s wind math, run in your browser. The app draws the runway and the wind on a compass rose, grades the crosswind and gust against limits you set and saves per aircraft, ranks every runway heading 01 to 36 for the wind you have, and works out density altitude.
How this was checked
The numbers on this page come from the same trigonometry as the Crosswind Calculator iOS app, and an automated test compares them with the app’s own code on a grid of winds and runways (last run ). Statements about runway numbers, METAR and tower wind, and handbooks are quoted from FAA publications, linked where they appear. This is a training and planning aid, not for primary flight operations, and it does not know your airplane’s limits. If something here is wrong, tell us at a@noshu.net.