Crosswind component
A 20-knot wind from 240 degrees on runway 18 splits into 10 knots of headwind and about 17.3 knots of crosswind from the right. Enter the wind speed, the direction it blows from and your heading. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Wind speed
- 20
- Wind direction
- 240
- Heading
- 180
- Relative angle
- 60
- Crosswind
- 17.320508
- Headwind
- 10
Pilots, cyclists, sailors, and anyone reading a wind report already know the raw speed and the direction the wind is blowing from. What they actually need on a runway, a road, or a boat course is how much of that wind acts along the heading and how much pushes sideways. This crosswind calculator accepts wind speed, meteorological wind direction, and a runway or travel heading, then returns both the crosswind component and the headwind component in the same unit as the speed you supplied.
How wind direction and heading become two components
Meteorological wind direction is the compass point the wind is blowing FROM, measured clockwise from north: zero or three hundred sixty is a north wind, ninety is from the east, one hundred eighty from the south, and two hundred seventy from the west. Heading is the direction the runway, vehicle, or hull is pointing, also clockwise from north — runway 18 is heading one hundred eighty, a bicycle computer reading two seven zero is a westbound course. The relative angle is wind direction minus heading.
Crosswind equals wind speed times the sine of that difference; headwind equals wind speed times the cosine of the same difference. At a relative angle of zero the entire speed is headwind and the crosswind is zero. At ninety degrees the entire speed is crosswind and the headwind is zero.
At one hundred eighty degrees the speed is a pure tailwind, reported as a negative headwind. Intermediate angles scale smoothly, so a sixty-degree difference on a twenty-knot wind yields ten knots of headwind and about seventeen point three knots of crosswind. Positive crosswind means the wind is from the right of the heading; negative crosswind means from the left.
That sign convention matches the usual aviation briefing card, so a published aircraft or vehicle limit can be compared with the absolute value without a second mental flip.
Where the two components are used and how pricing works
Flight-planning tools, ATIS briefings, and flight-school trainers compute both components for each candidate runway and compare the absolute crosswind with the aircraft limit. Drone and UAS ground stations do the same against a published maximum before they release a takeoff. Sailors and motor-vessel watchkeepers split a forecast into a head-sea and a beam-sea so they can choose a course that stays inside comfort or stability limits.
Cyclists, runners, and time-trialists convert a weather-app wind into a headwind they will actually feel on a known road heading. Motorsport race control and rail or highway operations teams apply the same split when a gust limit is written as a crosswind maximum on a specific track or span. Because each successful request is a single item of pure arithmetic, latency is dominated by the task handshake rather than computation, which suits high-frequency form validation as well as batch reprocessing of archived wind tables.
The interactive tool above runs free in the browser.
What you can do with it
Runway selection from METAR wind
Feed the reported wind speed and wind-from plus each runway heading, then pick the surface with the smallest absolute crosswind before takeoff or landing.
Bike, boat, and road heading checks
Convert a forecast wind-from and a known course heading into the headwind you will feel and the crosswind that will push you off the line.
Drone, UAS, and race-control limits
Compare both signed components against a published maximum so a hold or go decision matches the heading actually in use.
FAQ
What does a negative headwind or crosswind mean?
A negative headwind is a tailwind (the wind has a component along the heading). A negative crosswind is from the left of the heading; a positive crosswind is from the right.
Which units should I use for wind speed?
Any consistent unit — knots, metres per second, miles per hour, or kilometres per hour.
How is the crosswind component calculated?
Take the difference between the wind direction and your heading. The crosswind is the wind speed times the sine of that angle, and the headwind is the wind speed times its cosine.
What heading do I enter for a runway number?
Multiply the runway number by ten. Runway 18 points to 180 degrees, so a wind from 240 sits 60 degrees off the nose and to the right.
Is the wind direction where the wind comes from or where it goes?
Where it comes from, measured clockwise from north, as in weather reports. A wind of 90 blows from the east and a wind of 270 from the west.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/life/crosswind \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"wind_speed":20,"wind_direction":240,"heading":180}'const res = await fetch("https://api.kit.forhosting.com/life/crosswind", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"wind_speed": 20,
"wind_direction": 240,
"heading": 180
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/life/crosswind",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"wind_speed": 20,
"wind_direction": 240,
"heading": 180
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/life/crosswind", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"wind_speed":20,"wind_direction":240,"heading":180}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"wind_speed":20,"wind_direction":240,"heading":180}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/life/crosswind", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"wind_speed": 20,
"wind_direction": 240,
"heading": 180
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "life.crosswind",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Directions must lie between 0 and 360 degrees inclusive; an angle outside that band fails with invalid_input and is never billed.
Input contract, response fields, and the 0–360 rule
Every angle must sit in the closed interval from 0 to 360 degrees. Missing, empty, or non-numeric values fail and are not billed. Send three finite numbers: wind_speed as a non-negative speed in any unit you already use, wind_direction as the FROM direction in degrees, and heading as the runway or travel heading in degrees. Aliases are accepted in the same roles — speed, wind, or v for wind_speed; wind_dir, wind_from, or wind_from_deg for wind_direction; heading_deg, runway, runway_heading, or course for heading — so a METAR parser and a GPS logger can post without renaming columns. Three hundred sixty is accepted because it is the same compass point as zero; four hundred, minus ten, or five hundred forty are rejected with invalid_input that names the field and says it is outside 0 to 360 degrees. A negative wind_speed is rejected the same way. On success the body echoes the three inputs, reports relative_angle as the difference wrapped into the half-open range from 0 up to but not including 360, and returns signed crosswind and headwind plus a unit marker same_as_wind_speed and the formula string. There is no network fetch, no model call, and no clock: the same three numbers always yield the same JSON.
Where the two components are used and how pricing works
Use this endpoint whenever the source data is a wind-from and a heading rather than a pre-reduced relative angle. Programmatic calls use the prepaid KIT balance at $0.002 per successful request, with no subscription and no charge when validation fails. Document the wind-speed unit in your own schema so downstream consumers know whether limits are in knots or metres per second — the calculator does not convert units, so you stay in the aviation, marine, or road standard you already use.
Technical questions
How do I calculate crosswind and headwind from wind and heading?
Send wind_speed, wind_direction (the FROM direction in degrees), and heading. Crosswind is speed times sine of (wind_direction minus heading); headwind is speed times cosine of the same difference. Both come back in one response.
What range of angles does the crosswind calculator accept?
Both wind_direction and heading must be finite numbers from 0 to 360 degrees inclusive. A value outside that band, such as 400 or −10, fails with invalid_input and is not billed.
Is the crosswind calculator free?
The browser tool is free. API calls cost $0.002 per successful request from your prepaid KIT balance; failed validation is never charged.