Crosswind Calculator
Enter the runway number and the wind to get the crosswind and headwind components, the side the wind comes from, and the effect of the gust.
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The crosswind calculator splits the wind into the part that blows across the runway and the part that blows along it. Type the runway number, the direction the wind comes from and its speed in knots. The result gives the crosswind component, the side it hits you from, and the headwind component, which turns negative when the wind blows from behind.
Add a gust speed to see the worst case, and a crosswind limit to see how much margin is left. The calculator reads the runway number as a magnetic heading, so a runway 27 is 270 degrees. Wind from a tower or ATIS is magnetic as well, while the wind inside a METAR or TAF is true, which matters when the two differ by the local variation.
How to use the crosswind calculator
- Enter the runway number, the two digits painted at the threshold, for example 27 for runway 27L, 27C or 27R. All three share the same heading.
- Enter the wind direction in degrees, the direction the wind blows from. Copy it from the ATIS, the tower or a METAR. A report of 31015G25KT gives a direction of 310, a speed of 15 and a gust of 25.
- Enter the wind speed in knots.
- Open More options to enter the gust speed and your own crosswind limit. A limit of 0 turns the check off.
- Read the crosswind and headwind figures. If the headwind is negative, the runway has a tailwind and the warning tells you so, so look at the opposite end.
- Open How it was calculated to see the angle and both products with your numbers.
The example wind in the form is already filled in, so the first result appears as soon as the page loads. Use the preset buttons to load a wind straight down the runway, a 40 degree wind, a gusty crosswind or a tailwind. Copy link saves your inputs in the address, Print / save result makes a sheet with the date, and Reset restores the example.
How do you calculate a crosswind component?
Subtract the runway heading from the wind direction to get the angle between them, then multiply the wind speed by the sine of that angle. For runway 27 (heading 270) and a wind of 310 at 15 knots the angle is 40 degrees, sin 40 is 0.6428, so the crosswind is 15 x 0.6428 = 9.6 knots. The headwind uses the cosine: 15 x cos 40 = 15 x 0.7660 = 11.5 knots.
The sign of the angle gives the side. A wind clockwise from the runway heading hits the aircraft from the right, a wind counter-clockwise from the left. The calculator wraps the angle through north, so runway 36 with a wind of 350 is 10 degrees off from the left.
What is the crosswind rule of thumb?
Pilots often use the clock method instead of a calculator: a wind 30 degrees off the runway gives half of its speed as crosswind, 45 degrees gives about 70 percent, and 60 degrees or more gives about 90 percent to the whole speed. The table under the result shows the real sine and cosine values. Sine 30 is exactly 0.5 and sine 45 is 0.707, so the first two shortcuts are accurate, while sine 60 is 0.866 and the 90 percent shortcut rounds up on the safe side.
How do gusts change the crosswind?
Plan with the gust, not with the steady wind. The same angle applies, so the gust crosswind is the gust speed times the sine of the angle. In the gusty preset a wind of 12 knots gusting 22 from 140 on runway 9 is 50 degrees off, so the steady crosswind is 9.2 knots but the gust crosswind is 16.9 knots. The calculator shows both so you can compare the number against your limit.
Where do I find the maximum crosswind for my aircraft?
Look for the “demonstrated crosswind component” in the aircraft flight manual or the pilot operating handbook. It is the highest value the manufacturer’s test pilots met during certification. It is not a legal limit for most light aircraft, but many pilots and flight schools set personal or club limits below it. Type your own limit into the calculator and it will report the margin or warn when the crosswind is above it.
Why can a crosswind figure be wrong by a few knots?
The runway number is rounded to the nearest 10 degrees, so the true runway heading can differ by up to 5 degrees. Winds in a METAR are true, winds from ATIS and the tower are magnetic, and the two can differ by the local magnetic variation. Reported wind is also an average over two minutes. Treat the result as an estimate to decide whether to continue, and use the live wind on short final.
Sources
Formulas are plane geometry. Runway numbering follows ICAO Annex 14 and the FAA Aeronautical Information Manual, which both round the magnetic heading to the nearest 10 degrees. METAR wind format follows the FAA Aeronautical Information Manual chapter 7. Checked October 2026.
Questions from readers
What does the crosswind component mean?
It is the part of the wind that pushes the aircraft sideways across the runway. The rest of the wind, the headwind or tailwind component, blows along the runway and changes your ground speed.
Is runway 27L different from 27R for crosswind?
No. The letters only separate parallel runways. All runway 27 variants point to about 270 degrees magnetic, so they give the same components.
What is the crosswind for a 90 degree wind?
The full wind speed. At 90 degrees the sine is 1 and the cosine is 0, so a 20 knot wind from the side is a 20 knot crosswind with no headwind.
Which wind do I use, magnetic or true?
Use the reference that matches the runway heading. The runway number is magnetic, so use magnetic wind from ATIS or the tower. For a METAR or TAF, which give true wind, correct it by the local magnetic variation first.
How do I read a gust in a METAR?
A group like 27018G30KT means wind from 270 at 18 knots with gusts to 30. Enter 270, 18 and 30 in the wind direction, speed and gust fields.
Does this calculator tell me whether landing is safe?
No. It converts a wind into components. Whether the landing is within your skill, the aircraft limits and the runway conditions is your decision as pilot in command.
What are headwind and tailwind?
A headwind is wind blowing toward you from the front of the runway, while a tailwind blows from behind. The tool shows headwind as a signed number in knots. A positive value means a headwind, and a negative value means a tailwind. If you get a negative result, the tool warns you that the runway has a tailwind, so check the other end.
How do I use a crosswind component chart?
The table under the result works as a chart for the wind speed you entered. Find the row closest to your wind angle, then read the crosswind column.
- Enter the wind speed in knots.
- Find the row nearest your wind angle, from 10 to 90 degrees.
- Read the crosswind value in that row. For the headwind, use the same wind speed with the cosine of that angle instead.
For example, 15 kt at 40 degrees gives a crosswind of 9.6 kt and a headwind of 11.5 kt.
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- E6B flight computer: use it for the wind triangle, time, speed, distance and fuel together.
- METAR decoder: use it to read the wind group from a weather report.
- Density altitude calculator: use it to check how hot and high conditions lengthen the takeoff run.
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- Wind and navigation tools: the full set of wind, course and distance calculators.