E6B Flight Computer
An online version of the pilot's E6B: solve the wind triangle for wind correction angle, heading and ground speed, then work out time, speed and distance, fuel burn and endurance, and common aviation unit conversions. Every answer shows the math.
Last updated:
Winds aloft forecasts are given in degrees true
From the compass card, e.g. +2 or −1
Gives time en route
Gives fuel for the leg
h:mm (1:20), h:mm:ss, or minutes (80)
h:mm, h:mm:ss, or minutes
How to use the E6B Flight Computer
- Pick a calculator: wind triangle, time-speed-distance, fuel or conversions.
- For the wind triangle, enter TAS, true course and the forecast wind (true direction and speed).
- Add variation and deviation to get magnetic and compass headings, and a leg distance for time en route.
- For time, speed or fuel, choose what to solve for and enter the other two values (time as h:mm).
- Read the result and the step-by-step working, then copy it to your navigation log.
Wind triangle formulas
The wind triangle has three vectors: the heading and true airspeed (where the airplane points), the wind (where the air moves), and the course and ground speed (where the airplane actually goes).
- Wind correction angle: WCA = asin(W × sin(Wd − TC) / TAS)
- True heading: TH = TC + WCA
- Ground speed: GS = TAS × cos(WCA) − W × cos(Wd − TC)
- Magnetic heading: MH = TH − east variation (or + west variation). Compass heading: CH = MH ± deviation.
- Time, speed, distance: D = S × T. Fuel: fuel = burn rate × time.
Worked example: TC 090°, TAS 120 kt, wind 030° at 20 kt. The wind is 60° left of the nose, so WCA = asin(20 × −0.866 / 120) = −8.3°, TH ≈ 082°, and GS = 120 × 0.990 − 20 × 0.5 ≈ 108.7 kt. An 85 nm leg takes about 47 minutes.
Quick reference
| Conversion | Value | Rule of thumb |
|---|---|---|
| 1 nautical mile | 1.15078 statute miles · 1.852 km | nm × 1.15 = sm |
| 1 knot | 1.15078 mph · 1.852 km/h | kt ÷ 60 = nm per minute |
| 1 foot | 0.3048 m | m × 3.28 = ft |
| °C to °F | °F = °C × 9/5 + 32 | Double it and add 30 (rough) |
| 1 US gallon | 3.785 L | Avgas 6.0 lb, Jet A about 6.7 lb |
| 1 inHg | 33.864 hPa | 29.92 inHg = 1013.25 hPa |
Tips for flight planning
- Use true values together. Measure the true course on the chart and use true winds aloft; convert to magnetic only at the end.
- Use the forecast for your cruise altitude. Interpolate winds aloft between the forecast levels, and get TAS from the true airspeed calculator.
- Plan each leg. Wind and course change between checkpoints, so run the triangle for every leg of the navigation log.
- Add reserves. The leg fuel shown here has no reserve; plan the total with the aviation fuel calculator.
Frequently asked questions
What does an E6B flight computer do?
An E6B is a circular slide rule with a wind side, used by pilots for flight planning. It solves the wind triangle (heading and ground speed), time-speed-distance and fuel problems, true airspeed and density altitude, and unit conversions. This page does the same calculations with exact trigonometry instead of a slide rule.
How do you calculate the wind correction angle?
WCA = arcsin(wind speed × sin(wind direction − true course) / true airspeed). Add it to the true course to get the true heading. For example, a true course of 090°, TAS 120 knots and wind from 030° at 20 knots gives WCA = arcsin(20 × sin(−60°) / 120) = −8.3°, so the true heading is about 082°.
How is ground speed calculated from the wind?
Ground speed = TAS × cos(WCA) − wind speed × cos(wind direction − true course). With TAS 120 knots, WCA 8.3° and a wind 60° off the nose at 20 knots, the ground speed is 120 × 0.990 − 20 × 0.5 ≈ 108.7 knots.
How do I get magnetic heading from true heading?
Apply the magnetic variation shown on the sectional chart: subtract easterly variation and add westerly variation (east is least, west is best). Then apply compass deviation from the compass correction card to get the compass heading.
Is the wind direction true or magnetic?
Winds aloft forecasts and METAR/TAF winds are true, which is what the wind triangle needs along with the true course from the chart. Winds from ATIS, AWOS and the tower are magnetic and are used for runway crosswinds.
How do I enter time?
Type hours and minutes with a colon, like 1:20 for one hour twenty minutes, or 0:45:30 with seconds. A plain number is read as minutes, so 80 means 1:20.
Can I use this instead of a real E6B on a checkride?
Use it for planning, study and checking your work. Whether an electronic or online computer is allowed on a knowledge test or checkride depends on the testing rules and examiner, so check the current requirements and practice with the tool you will use.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.