Crosswind & Headwind Component Calculator

AVIATION CROSSWIND FLIGHT PLANNING PILOTS
Share:
By Checked against sources by , Founder & Architect, RECATOOLS Published Updated Last reviewed

Crosswind and headwind component calculator. Splits wind into crosswind and headwind/tailwind from the runway heading, wind direction and speed. Educational.

RT-OUT-002 · Outdoors & Recreation
Your browser is too old for this tool’s interactive features. Please update to Safari 13.1, Chrome or Edge 80, Firefox 74 or newer.

Crosswind and Headwind Component Calculator

⚠ Disclaimer: This tool is for educational use only. It is NOT a substitute for the official Aircraft Flight Manual, current METAR/TAF/NOTAM data, or the rules and publications of your aviation authority (such as CAAS in Singapore, CAAM in Malaysia, the FAA, the UK CAA, CASA or Transport Canada). Pilots remain solely responsible for all flight planning, performance calculations, and operational decisions. RECATOOLS is not certificated for navigation or flight operations.
Heading in degrees, e.g. 090. A runway number (1–36, e.g. 9) is read as × 10, and the result says so.
📅 Research current as of 16 Oct 2026 · Sources: Angle = wind dir − runway heading. Crosswind = speed × sin(angle); headwind = speed × cos(angle) (negative = tailwind), as in CAA New Zealand's Flight Instructor Guide. Wind references from FAA AIM 7-1-10 and 7-1-29 and WMO-No. 782; runway numbering from AIM 2-3-3 and the Malaysia AIP (WMKK AD 2.12); certification crosswind from 14 CFR 23.233 (removed 2017) and 25.237.
Standards, published formulas, and reference data are revised over time — check against a current authoritative source before relying on these figures.
Advertisement
After results · AD-W1Responsive · Post-tool

How to use the crosswind calculator

Enter the runway heading

Type the heading in degrees for the end you will use, such as 090. If you type the runway number instead (1 to 36, such as 9 or 27), the calculator reads it as the number × 10 and says so under the result; to mean a heading of 9°, type 009. The FAA's rule is that a runway number is "the whole number nearest one-tenth the magnetic azimuth" of the centreline (AIM 2-3-3), but a published heading can sit several degrees from its number: at Kuala Lumpur International, runways 14L and 14R both lie on 146.01° true, with magnetic variation 0° (Malaysia AIP, WMKK AD 2.12, issue effective 11 Aug 2026). Use the published heading when you have it.

Enter the wind

Type the direction the wind is coming from and its speed in knots. Make sure the wind direction and runway heading are referenced the same way. The FAA's Aeronautical Information Manual says ATIS and ASOS/AWOS voice broadcasts give wind relative to magnetic north (AIM 7-1-10), like the runway, while METAR text gives it "referenced to true north" (AIM 7-1-29). CAA New Zealand's instructor guide says the same of METAR and TAF winds.

Add the gust (optional)

If the wind is gusting, enter the gust speed too. The calculator resolves the gust the same way as the steady wind and shows the crosswind and the headwind or tailwind at the gust. A gust at or below the steady speed is not used, and the result says so.

Read the components

You get the crosswind across the runway, the headwind or tailwind along it, and the wind angle. A component under 0.5 kt is shown as negligible rather than given a side or a direction. The calculator describes the wind; it does not say whether a runway, a takeoff or a landing is suitable.

Advertisement
After how-to · AD-W2Responsive

Wind components — splitting the wind across and along the runway

Trigonometry on the runway

Wind almost never blows straight down the runway, so pilots resolve it into two parts: the headwind component, which acts along the runway, and the crosswind component, which acts across it. The split is pure trigonometry. CAA New Zealand's Flight Instructor Guide puts it as "XWC = V × Sineθ": the crosswind component is the wind speed multiplied by the sine of the angle between the wind direction and the runway heading, and the headwind component is the wind speed multiplied by the cosine. Its own example is runway 21 with a wind from 240° at 20 kt: 30° off, so 10 kt of crosswind and 17.3 kt of headwind, which is what this calculator gives if you type 21 as the runway. With the wind straight down the runway the angle is zero, so it is all headwind; at 90° it is all crosswind; beyond 90° the cosine goes negative, which is a tailwind. The sines of the common angles are 0.5 at 30°, about 0.71 at 45° and about 0.87 at 60°.

The clock rule, and where it reads high

The same instructor guide teaches a mental shortcut using a watch face. A 30° difference is thirty minutes, half way round, so the crosswind is half the wind; 45° is three-quarters of the way round, so three-quarters of the wind; and from 60° the guide says to "consider the crosswind component to be the full strength of the wind". Set against the sine, the rule is exact at 30° and 90° and reads high in between: at 45° it gives 0.75 of the wind where the sine gives 0.71, and at 60° it gives the whole wind where the sine gives 0.87. In a 20 kt wind 60° off, the clock says 20 kt and this calculator gives 17.3 kt. That gap, about 13% of the wind speed, is the rule's largest overestimate, and it grows with the wind.

The demonstrated crosswind

Aircraft are flight-tested for crosswind. For small aeroplanes the US rule, 14 CFR 23.233(a), required a 90° crosswind component "demonstrated to be safe for taxiing, takeoff, and landing" of "not less than 0.2 VSO": a floor of two-tenths of the stalling speed in landing configuration, which is 9 kt for a 45 kt stall. That section was removed effective 30 August 2017, and the current Part 23 text states no crosswind figure. For transport-category aeroplanes, 14 CFR 25.237(a)(1) requires a demonstrated value of "at least 20 knots or 0.2 VSR0, whichever is greater, except that it need not exceed 25 knots". CAA New Zealand describes the resulting maximum demonstrated crosswind as "not a legal limitation", and a 2016 FAA safety leaflet calls it "not a limitation but rather the maximum cross wind experienced in the course of flight testing for certification".

"At 60° the sine puts 0.87 of the wind across the runway. The clock rule rounds that up to all of it."

What the inputs can hide

The arithmetic is exact, but the inputs are not. The wind direction and the runway heading must be expressed the same way, magnetic with magnetic or true with true; mixing them shifts the angle by the local magnetic variation. At Singapore Changi that variation is 23′ east (2020 epoch, CAAS aerodrome chart AOC-1), under half a degree. The rounding in the report itself can matter more: under WMO-No. 782 a METAR wind is "the 10-min mean", reported "in steps of 10° true and 1 kt", so the direction can sit up to 5° from the measured mean. In a 20 kt wind near the runway axis, 5° is 1.7 kt of crosswind; type 090 and then 095 as the wind direction against runway 090 to see it. The same handbook says a gust is reported only when "the maximum gust speed has exceeded the mean speed by 10 kt (5 m s–1) or more". And the components say nothing about wind shear or turbulence. This calculator is an educational aid that describes the wind; decisions belong to the pilot, using current official weather and the aircraft's approved data.

Sine across the runway, cosine along it

01

Crosswind = wind speed × sin(angle).

02

Headwind = wind speed × cos(angle).

03

Beyond 90° the headwind becomes a tailwind.

04

sin 30° = 0.5; sin 45° ≈ 0.71; sin 60° ≈ 0.87.

05

KLIA runways 14L and 14R lie on 146.01° true, not 140°.

06

Clock rule (CAA NZ): 30° = half, 45° = three-quarters, 60° or more = all of the wind.

07

FAA AIM: ATIS wind is magnetic; METAR wind is true.

08

The clock rule's largest overestimate is at 60°: 20 kt for a true 17.3 kt.

09

Old US small-aeroplane rule: demonstrated crosswind not less than 0.2 × VSO, removed 2017.

10

METAR wind: a 10-minute mean in 10° steps (WMO-No. 782).

Frequently asked questions

  • Take the angle between the wind direction and the runway heading, then multiply the wind speed by the sine of that angle. The headwind component is the wind speed times the cosine of the angle. For example, a 20-knot wind 30° off the runway gives a crosswind of 20 × sin30° = 10 knots and a headwind of 20 × cos30° ≈ 17.3 knots. The calculator does this and also tells you which side the crosswind is from.

  • The heading of the runway end you will use, in degrees, on the same reference as the wind. Under the FAA's rule the runway number is the magnetic heading rounded to the nearest 10° (AIM 2-3-3), but the published heading is the one to use: Kuala Lumpur International's runways 14L and 14R lie on 146.01° true with 0° variation (Malaysia AIP, issue effective 11 Aug 2026), six degrees from the number. If you type a runway number from 1 to 36, the calculator reads it as the number × 10 and says so; type 009 if you mean a heading of 9°. Runway 09 and runway 27 are the same strip in opposite directions, and the components differ completely between them.

  • It is the crosswind demonstrated in certification flight testing. For US small aeroplanes, 14 CFR 23.233(a) required it to be "not less than 0.2 VSO", a floor rather than a ceiling, until the section was removed effective 30 August 2017; the current Part 23 text gives no crosswind figure. For transport-category aeroplanes, 14 CFR 25.237(a)(1) requires "at least 20 knots or 0.2 VSR0, whichever is greater, except that it need not exceed 25 knots". CAA New Zealand calls the demonstrated figure "not a legal limitation", and a 2016 FAA safety leaflet calls it "not a limitation but rather the maximum cross wind experienced in the course of flight testing for certification".

  • Because the angle must be measured between two directions on the same reference. Runway numbers are magnetic. The FAA's AIM says ATIS and ASOS/AWOS voice broadcasts report wind relative to magnetic north, while METAR text reports it relative to true north; CAA New Zealand says METAR and TAF winds are in degrees true. Mixing a true wind with a magnetic runway heading shifts the angle by the local magnetic variation. At Singapore Changi that is 23′ east (2020 epoch), under half a degree; where the variation is larger, so is the error. Convert so both are on the same reference.

  • CAA New Zealand's Flight Instructor Guide teaches it with a watch face: 30° off is half the wind, 45° is three-quarters, and from 60° take the full wind strength. The exact values are the sines: 0.5 at 30°, about 0.71 at 45° and about 0.87 at 60°. So the rule matches at 30° and 90° and reads high in between, most at 60°, where a 20-knot wind gives 20 knots by the rule and 17.3 knots exactly. The calculator gives the exact figure.

  • The crosswind and the headwind or tailwind at the gust speed, resolved at the same angle as the steady wind, so each is larger than the steady figure by the ratio of gust to steady speed. Under WMO-No. 782 a METAR reports a gust only when the maximum gust has exceeded the mean speed by 10 kt or more. A gust entered at or below the steady speed is not used, and the calculator says so instead of leaving the gust cards blank without explanation.

  • When the wind blows from more than 90° off the runway heading, the along-runway component comes from behind: a tailwind, which adds to ground speed for the same airspeed. The calculator shows its size with the label TAILWIND, in a red band, when it is 0.5 kt or more, for the steady wind or the gust. A smaller along-runway component is shown as negligible, because a fraction of a knot is below the 1 kt steps a METAR reports.

  • No. It gives the wind components, but the decision to land, take off, choose a runway, or divert is the pilot's, made from current official weather, the aircraft's approved data and runway condition. The numbers don't capture wind shear, turbulence, or how the aircraft actually feels.

  • Yes. Enter any runway heading from 0 to 360° (or a runway number from 1 to 36) and any wind direction and speed, and it resolves the components; values outside 0 to 360° are refused rather than wrapped silently. The trigonometry is the same for any aircraft. Keep the wind and runway on the same reference, and remember the reported wind is an average.

  • No. The values you enter are processed entirely in your browser. Nothing is sent to a server, stored, or shared, and no account is required. The calculation runs on your device only.

Method & sources

How it computes

Angle = wind direction - runway heading, signed to (-180, 180]. Crosswind = speed x sin(angle), positive from the right; headwind = speed x cos(angle), negative = tailwind. A runway typed as 1-36 is read as its number x 10 and flagged; 009 is a heading. Components under 0.5 kt are shown as negligible. A gust above the steady speed is resolved the same way (crosswind and head/tailwind); one at or below it is not used, with a message. AviationKernel.windComponents, tested.

What this tool implements

  • Corrected 2026-10-16: the old 14 CFR 23.233(a) rule set the demonstrated crosswind as a floor, "not less than 0.2 V SO", not a ceiling ("up to"), and the section was removed effective 30 Aug 2017; transport aeroplanes, 14 CFR 25.237(a)(1): at least 20 kt or 0.2 VSR0, need not exceed 25 kt. Removed as not verified: "no exceptional degree of skill", placarding after 3 May 1962, and the PHAK tailwind-chart figures.
  • A runway number is the magnetic heading to the nearest 10 degrees under FAA AIM 2-3-3, but published headings can differ: KLIA 14L/14R are 146.01 degrees true with 0 degrees variation (Malaysia AIP WMKK AD 2.12, effective 11 Aug 2026). The calculator no longer reads a typed "9" as 9 degrees.
  • Wind references: ATIS and ASOS/AWOS voice wind is magnetic (AIM 7-1-10); METAR wind is true (AIM 7-1-29; CAA NZ); METAR wind is a 10-minute mean in 10-degree steps and a gust is reported when it exceeds the mean by 10 kt or more (WMO-No. 782). The page describes components only and gives no runway-choice advice.

Sources

Advertisement
Pre-footer · AD-W3 728 × 90