Crosswind Calculator
A 20 knot wind sounds manageable until you learn how much of it is actually pushing you sideways toward the runway edge. What matters on takeoff and landing is not the total wind but its crosswind component, and that depends on a single angle: the difference between where the wind comes from and where the runway points.
Enter the wind speed, the wind direction, and the runway heading, and this calculator resolves the wind into its crosswind component, its headwind or tailwind component, and the side the crosswind comes from, so you can compare the right number with your aircraft limit.
Planning aid only. Compare the crosswind component with the maximum demonstrated crosswind in your aircraft handbook and your own currency, and always follow ATC instructions and local procedures.
Quick Answer
Key takeaways
- Crosswind component = wind speed x sin(wind angle). Headwind component = wind speed x cos(wind angle). The angle is the difference between the wind direction and the runway heading.
- Aircraft limits apply to the component, never the total wind. A 30 knot wind 10 degrees off the runway is only a 5.2 knot crosswind; the same wind at 90 degrees is a full 30 knot crosswind.
- Always run the gust through the same calculation. The gust component is the one you will actually meet in the flare.
- Written METAR and TAF winds are in degrees true and runway numbers are magnetic. Convert before you compare where variation is large.
- Quick Answer
- How to use the crosswind calculator
- The wind triangle behind the numbers
- Worked example: runway 24, wind 270 at 20 gusting 28
- Demonstrated limits, personal limits, and when the answer is no
- The true north trap in written weather reports
- What competing calculators miss
- Frequently Asked Questions
- Add This Calculator to Your Website
- References
How to use the crosswind calculator
Take the wind from your ATIS, tower report, or METAR and enter three numbers. Wind speed is the reported speed in knots. Wind direction is the direction the wind is blowing from, so a west wind is entered as 270. Runway heading is the runway number multiplied by 10: runway 24 becomes 240. Press Calculate Components and the tool returns the crosswind component as the headline figure, the side it comes from, the headwind or tailwind component along the runway, and the wind angle it used.
Two habits make the result trustworthy. First, use the heading of the runway direction you will actually use. Runway 24 and runway 06 are the same strip of pavement pointing opposite ways, and the same wind is a headwind crosswind from the right on one and a tailwind crosswind from the left on the other. Second, if the report includes a gust, run the calculation a second time with the gust speed in the wind speed box. The gust case below shows why: at a 30 degree angle, a gust from 20 to 28 knots lifts the crosswind from 10.0 to 14.0 knots, which can cross a training aircraft limit even though the steady wind looked comfortable. If you are planning the flight rather than sitting at the hold, the air distance calculator works out the route distance the wind will be acting over.
The wind triangle behind the numbers
The reported wind is a single vector, but the runway only cares about two directions: along it and across it. Resolving the vector into those two components is basic trigonometry, the same decomposition the cross product calculator explores for vectors in general, and it is why the two components can add up to more than the original wind speed (10.0 + 17.3 = 27.3 from a 20 knot wind is normal vector arithmetic, not an error).
The sine and cosine split explains the pattern every pilot internalizes. Close to the runway heading, the angle is small, sine is near zero, and almost all of the wind works for you as headwind. As the angle opens toward 90 degrees, sine climbs toward 1 and the crosswind takes over, while the headwind fades to nothing. Past 90 degrees the cosine turns negative, which is the mathematics telling you the along-runway part is now pushing you from behind: a tailwind. The size of the angle itself is a plain subtraction, the same operation the central angle calculator handles for directions measured around a compass point.
| Wind angle | Crosswind share of wind speed | Headwind share of wind speed | For a 20 knot wind |
|---|---|---|---|
| 0 degrees (straight down the runway) | 0% | 100% | 0.0 kt crosswind, 20.0 kt headwind |
| 10 degrees | 17% | 98% | 3.5 kt crosswind, 19.7 kt headwind |
| 30 degrees | 50% | 87% | 10.0 kt crosswind, 17.3 kt headwind |
| 45 degrees | 71% | 71% | 14.1 kt crosswind, 14.1 kt headwind |
| 60 degrees | 87% | 50% | 17.3 kt crosswind, 10.0 kt headwind |
| 90 degrees (straight across) | 100% | 0% | 20.0 kt crosswind, 0.0 kt headwind |
The old cockpit rule of thumb matches this table: at 30 degrees take half the wind as crosswind, at 45 degrees take about 70 percent, at 60 degrees take about 90 percent. The calculator simply replaces the rounding with the exact sine and cosine values.
Worked example: runway 24, wind 270 at 20 gusting 28
The calculator is pre-filled with the steady case, and every figure below is what it returns.
| Step | Working | Result |
|---|---|---|
| Wind angle | 270 minus 240 | 30.0 degrees |
| Crosswind component | 20 x sin(30 degrees) = 20 x 0.500 | 10.0 knots, from the right |
| Headwind component | 20 x cos(30 degrees) = 20 x 0.866 | 17.3 knots |
| Gust case crosswind | 28 x sin(30 degrees) | 14.0 knots, from the right |
| Gust case headwind | 28 x cos(30 degrees) | 24.2 knots |
Read against a common trainer limit, the steady 10.0 knot crosswind sits comfortably inside the Cessna 172 maximum demonstrated crosswind of 15 knots. The gust case at 14.0 knots nearly reaches it. That gap between the two runs of the same calculation is the real lesson: the decision rarely turns on the steady wind, and a pilot who only ever calculates the first number is planning for the calmest moment of the approach rather than the worst one.
Demonstrated limits, personal limits, and when the answer is no
The number printed in the pilot operating handbook is called the maximum demonstrated crosswind, and the word demonstrated does real work. It records the strongest crosswind component present during certification testing; as the AVweb technique coverage of crosswind components explains, it is a guide rather than a regulatory limit for most general aviation operations, and the certification floor itself is tied to 0.2 times the stall speed in the landing configuration. A Cessna 172 lists 15 knots and a Cessna 152 lists 12, while larger types demonstrate 30 knots or more. None of that makes 14.9 knots safe for a pilot who has not flown a crosswind landing in a year.
Set a personal limit below the book number, and lower it further when the runway is wet or narrow or the wind is gusting. The tailwind case deserves its own caution: FAA handbook material on takeoff performance notes that a tailwind equal to 10 percent of the takeoff airspeed increases takeoff distance by roughly 21 percent, while the same headwind cuts it by about 19 percent. A quartering tailwind is the worst combination this calculator can show you, and the usual fix, using the reciprocal runway, turns both components in your favor at once.
The true north trap in written weather reports
One input error quietly corrupts crosswind calculations where magnetic variation is large. Written weather, the METAR and TAF you read on a screen, reports wind direction relative to true north; runway numbers, tower winds, and ATIS broadcasts are magnetic. The FAA Aeronautical Information Manual spells out the convention in its weather chapter: the METAR wind group is a three-digit true direction, as in the 22015G25KT example it decodes. Where variation is 12 degrees east, a METAR wind of 270 true is 258 magnetic, and comparing 270 directly with a runway heading of 240 misstates the wind angle by 12 degrees, at some fields understating the crosswind, which is the dangerous direction. Convert one figure to the other scale before you subtract; never mix the two in one calculation.
What competing calculators miss
The crosswind tools reviewed for this page all run the same sine and cosine, so the differences are in what surrounds the arithmetic.
Miss 1: the wrap-around runway. Several tools work out the crosswind side with a plain comparison of the two numbers, which breaks whenever the subtraction crosses north. Wind from 010 on runway 36 (heading 360) is a crosswind from the right, but a naive wind-greater-than-runway test calls it left. This calculator normalizes the signed angle first, so headings either side of 360 are handled correctly.
Miss 2: no gust workflow. Most tools present one answer for one wind speed and never prompt for the gust, even though gust spreads are when limits get breached. The how-to section here builds the second, gust-speed run into the standard check.
Miss 3: silence on true versus magnetic. Tools that accept a METAR wind and a runway number without mentioning the two north references bake a systematic error into every calculation at high-variation airfields. The trap is explained above, next to the tool, where it can stop the mistake.
One honest limit: this calculator resolves the wind you give it; it does not fetch live weather, model gusts between the reported values, or know your aircraft limit. Those judgments stay with the pilot, which is where certification puts them.
Frequently Asked Questions
It is the part of the wind that blows directly across the runway, at 90 degrees to the direction of travel. A wind reported at an angle to the runway always splits into a crosswind component across the runway and a headwind or tailwind component along it. Aircraft crosswind limits apply to the crosswind component, not to the total wind speed, which is why the split matters.
Multiply the wind speed by the sine of the angle between the wind direction and the runway heading. The headwind component is the same wind speed multiplied by the cosine of that angle. A 20 knot wind 30 degrees off the runway heading gives 20 x sin(30) = 10.0 knots of crosswind and 20 x cos(30) = 17.3 knots of headwind.
From. Aviation wind reports always give the direction the wind is coming from, so a wind reported as 270 is blowing from the west toward the east. Enter that reported number here. Entering the toward direction by mistake flips the answer by 180 degrees and turns a headwind into a tailwind on paper.
Multiply the runway number by 10. Runway 24 means a heading of about 240 degrees, runway 09 means 090 degrees, and runway 36 means 360 degrees (north). Use the heading of the runway direction you will actually take off or land on, not the reciprocal end.
It is the highest crosswind component the manufacturer demonstrated during certification testing, printed in the pilot operating handbook. A Cessna 172 lists 15 knots, for example. It is not a legal limit for most general aviation flying, but it is the most sensible personal ceiling until you have real crosswind experience, and many flight schools and insurers treat it as a hard limit.
Run both. The steady wind gives the planned component, and the gust gives the worst case you may meet in the flare. If the report says 270 at 20 gusting 30, calculate once at 20 knots and once at 30. Plan your technique and your go-or-no-go decision around the gust figure.
Written weather reports such as METAR and TAF give wind direction relative to true north, while runway numbers are based on magnetic north. Where magnetic variation is large, mixing the two without converting can shift the wind angle by 10 degrees or more and understate the crosswind. Tower and ATIS spoken winds are already magnetic, so they compare directly with the runway.
Sometimes, within strict limits. Many aircraft handbooks allow a small tailwind component, often up to 10 knots, but a tailwind lengthens the takeoff roll and landing distance sharply and reduces climb gradient. If this calculator shows a tailwind component on your chosen runway, the standard answer, traffic permitting, is to use the opposite runway direction and turn it into a headwind.
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References
- Federal Aviation Administration, “Aeronautical Information Manual, Chapter 7: Safety of Flight” – the official decoding of METAR and TAF wind groups, including the rule that written wind directions are given relative to true north. FAA: AIM Chapter 7, Safety of Flight. Accessed October 2026.
- Federal Aviation Administration, “Pilot’s Handbook of Aeronautical Knowledge” (FAA-H-8083-25) – takeoff and landing performance material on the effect of headwind and tailwind components on takeoff distance, and wind component charts. FAA: Pilot’s Handbook of Aeronautical Knowledge (PDF). Accessed October 2026.
- AVweb, “And They Called the Wind… Wind” – technique article on crosswind components, the meaning of maximum demonstrated crosswind, and the 0.2 Vso certification basis. AVweb: crosswind technique and demonstrated components. Accessed October 2026.
- Aviatopia, “Crosswind Explained: Components, Limits and Landing Technique” – explainer covering the sine and cosine component formulas, gust evaluation, and common crosswind myths. Aviatopia: Crosswind Explained. Accessed October 2026.
- XPConnect, “How to Read a METAR” – a worked decoding of a full METAR, including the wind group, gusts, and variable direction ranges, used here for the true-north reporting convention. XPConnect: How to Read a METAR. Accessed October 2026.