Crosswind Calculator

E6B Calculator – Digital Wind Component Calculator

Wind triangle in one place: enter true course, wind and true airspeed and the calculator returns wind correction angle, groundspeed and the crosswind/headwind components.

Wind Correction Angle
6.7° R
Groundspeed
94 kt
Crosswind
12.9 kt
Headwind
15.3 kt

What is the E6B flight computer?

The E6B flight computer is a circular slide rule pilots have used since World War II to solve fuel, time, distance and wind problems without a calculator. US Navy aviator Philip Dalton designed the original computer in the late 1930s for dead-reckoning navigation, and the US Army Air Corps adopted it for bomber crews in 1940, stamping it with the E-6B model number that gave the device its name. The design proved so useful that flight schools still teach it today, and the FAA requires it on the Private Pilot knowledge test and checkride.

Pilots nicknamed it the "whiz wheel" because the circular slide rule spins to solve multiplication, division, unit conversion, true airspeed, density altitude and wind problems on one device. The wind side is a grid under a rotating compass rose: a pilot marks wind speed and direction on the grid, rotates the bezel to the course or runway heading, and reads the crosswind and headwind components directly off the grid lines, along with the wind correction angle. Sporty's Pilot Shop, Jeppesen and ASA all sell E6B computers today, in plastic student versions and metal instructor-grade versions. For a quicker path to the same numbers, use the crosswind calculator on the home page, or keep reading below for the full wind triangle math.

How to use E6B for crosswind calculations

Set the wind direction at the top of the rotating azimuth ring first. Turn the transparent grid's compass rose so the wind direction lines up with the true index mark at the top of the E6B. This orients the grid so wind flows straight down toward the grommet at the center.

Mark the wind speed next. Using a pencil, make a dot straight up from the grommet, at a distance equal to the wind speed on the grid's speed scale. This dot represents the wind vector on the sliding grid.

Rotate the bezel to the true course or runway heading. Turn the outer ring so your course sits at the top index, without moving the pencil mark. The grid underneath now shows the wind relative to your direction of travel instead of relative to true north.

Read the crosswind and headwind directly. Count how many grid lines separate the pencil mark from the vertical centerline: that count is the crosswind component in knots. Count how far the mark sits from the grommet along the centerline: that is the headwind or tailwind component. The digital calculator above skips all four steps and returns the same two numbers the instant you type in your numbers.

Using an E6B for headwind calculations

The headwind side of the wind triangle uses the exact same setup as crosswind, just a different grid line. After marking the wind dot and rotating the course to the top index, look at how far the pencil mark sits above or below the grommet along the vertical centerline instead of side to side. A mark above the grommet reads as headwind, a mark below reads as tailwind. Because both readings come from one pencil mark, the E6B solves headwind and crosswind at the same time. You just look at a different axis. The digital version above solves both instantly and flags a negative headwind as a tailwind, since the label switches from "Headwind" to "Tailwind" whenever the value crosses zero.

Wind triangle explained

A wind triangle is three vectors that always close into a triangle: the true airspeed vector (aircraft heading and speed through the air), the wind vector (wind direction and speed), and the groundspeed vector (actual track and speed over the ground). Add the true airspeed vector to the wind vector, tip to tail, and the result is the groundspeed vector: heading plus wind equals track.

Crosswind and headwind are not separate numbers pulled from nowhere. They are the wind vector's two components once you rotate the whole triangle so the course line points straight up. The part of the wind vector that lines up with the course becomes headwind or tailwind. The part perpendicular to the course becomes crosswind. That is exactly what sin(angle) and cos(angle) compute in the calculator's code, and exactly what the E6B's grid lines show graphically.

Wind correction angle comes from the same triangle: it is the angle you must turn the true airspeed vector so that, once the wind vector is added, the resulting groundspeed vector points down the intended course. Every en-route flight plan, and every FAA and ICAO flight planning course, teaches this triangle before teaching any shortcut or app.

E6B Wind Correction Angle Worked Example

Take course 090°, wind from 360° at 20 kt, and true airspeed 100 kt, the same numbers you can type into the calculator above.

First find the angle between the course and the wind direction. Measuring the shorter way around the compass from 090° to 360° gives 90°. The wind blows exactly across the course, so this is a pure crosswind case.

WCA = arcsin((20 × sin(90°)) / 100) = arcsin(20 / 100) = arcsin(0.2) = 11.5°
Crosswind = 20 × sin(90°) = 20.0 kt
Headwind = 20 × cos(90°) = 0.0 kt
Groundspeed = 100 × cos(11.5°) − 0 = 98 kt

The calculator signs the angle by wind side, returning -11.5° because the wind comes from the left of course and the correction points left. Enter course 090, wind direction 360, wind speed 20 and TAS 100 into the calculator above and you will see the same four numbers: wind correction angle -11.5°, groundspeed 98 kt, crosswind 20.0 kt, and headwind 0.0 kt.

Digital E6B vs manual E6B

Digital E6Bs win on speed and accuracy. A phone or web calculator returns crosswind, headwind, groundspeed and wind correction angle the instant you finish typing, with no scale to misread and no parallax error from squinting at a plastic wheel. ForeFlight and Garmin Pilot both fold E6B math into full flight planning: pick a route, load winds aloft, and the app solves every leg's wind triangle automatically.

Manual E6Bs still earn their keep. They need no battery, no app store and no signal, so they work at altitude with a dead phone. Flight instructors and FAA examiners like them because working the wheel by hand forces a student to understand the wind triangle instead of trusting a black box. Most pilots end up owning both: a manual E6B for training and backup, a digital one like the calculator above for daily flight planning. See the wind correction angle calculator and the formulas reference for the math behind both versions.

Frequently Asked Questions

What does E6B stand for?+
E6B is not an acronym. It is the US Army Air Corps model number given to Philip Dalton's mechanical dead-reckoning computer when the military adopted it in 1940. Dalton had already sold earlier versions to civilian pilots and the Navy under different names. The military designation stuck, and "E6B" became the generic term for any circular flight computer, wind triangle solver, or its modern digital equivalent.
Do pilots still use the E6B?+
Yes. The FAA still tests E6B skills on the Private Pilot knowledge exam and checkride, so every student pilot learns the manual wheel at least once. In day to day flying, most pilots now solve the same wind triangle problems with a digital E6B app or a calculator like the one above, since it is faster and removes scale-reading error, but the underlying math is identical to the wheel.
Can the E6B calculate crosswind?+
Yes. The wind side of the E6B is built to decompose any wind into a crosswind component and a headwind or tailwind component, using the same trigonometry as the calculator above: crosswind equals wind speed times the sine of the angle between wind and course, and headwind equals wind speed times the cosine of that angle. Reading it off the grid takes longer than typing three numbers into the digital version, but the answer is the same.
Is the digital E6B as accurate as the manual one?+
The digital E6B is more accurate. It solves sine, cosine and arcsine with full floating-point precision, while a manual E6B depends on how carefully you read a printed scale, typically good to about plus or minus half a knot at best. That margin grows if the grid lines are worn or the pencil mark drifts. For checkride math the manual E6B is accurate enough. For real flight planning most pilots trust the digital result.
Where can I buy a physical E6B?+
Sporty's Pilot Shop, Jeppesen and ASA all sell E6B flight computers, in both plastic and aluminum versions. Plastic student models run about 20 to 40 dollars, while metal instructor-grade versions cost 50 to 100 dollars. Most flight schools stock them at their pilot supply counter, and every major online pilot shop carries at least one version alongside the digital apps from ForeFlight and Garmin.
What is a wind correction angle?+
Wind correction angle, or WCA, is the number of degrees a pilot adds to or subtracts from a course to fly the correct heading through moving air. Wind pushes the aircraft sideways off its intended track, so the pilot points the nose slightly into the wind to cancel that drift. WCA depends on wind speed, the angle between wind and course, and true airspeed, and the calculator above solves it the same way an E6B does.
How do you calculate groundspeed with an E6B?+
Groundspeed is true airspeed corrected for the wind's effect along the course. Once you know the wind correction angle, groundspeed equals true airspeed times the cosine of that angle, minus any headwind component, or plus any tailwind. A strong headwind and a large WCA both shave knots off groundspeed, while a tailwind adds them back. The calculator above runs this formula automatically every time you change wind, course or airspeed.
Related: Crosswind Calculator · Wind Correction Angle · Formulas