What is an E6B Flight Computer?
An E6B flight computer is the standard aviation tool used by pilots to solve navigation, performance, and weather calculations during preflight planning and in flight.
Originally a circular slide rule introduced in the 1930s, the physical E6B has two sides: a circular slide rule for airspeed and altitude problems, and a wind face for vector calculations. Every student pilot learns it because national aviation authorities require E6B proficiency on written and practical exams. An online E6B flight computer performs the same calculations digitally — same formulas, same results, without the manual alignment steps. Use the E6B flight computer at the top of this page to run any calculation instantly in your browser.
What Does an E6B Flight Computer Calculate?
The E6B flight computer covers every standard calculation a VFR or IFR pilot needs from preflight through landing. Each tool below links directly to that calculation.
Flight time Log elapsed time between engine start and shutdown, or between Hobbs meter readings. Supports both clock-based and Hobbs-based inputs, handles midnight wraparound, and returns flight time and air time separately.
Wind component Given a runway heading, wind direction, and wind speed, returns the headwind or tailwind component and the crosswind component in knots. Use this to confirm a runway is within your aircraft's demonstrated crosswind limit before committing to it.
Pressure altitude Converts your field elevation and current altimeter setting (QNH) to pressure altitude — the standardised reference used in performance charts and the flight levels. See the full pressure altitude guide for the formula and a worked example.
Density altitude Corrects pressure altitude for temperature to give the altitude at which the atmosphere has its current density. This is the figure that determines actual aircraft performance: takeoff roll, climb rate, and engine output all degrade as density altitude rises. See the full density altitude guide for the formula and a worked example.
True airspeed Converts indicated airspeed (IAS) to true airspeed (TAS) given pressure altitude and outside air temperature. TAS is the speed you actually move through the air mass, and the figure used for navigation and groundspeed calculation.
Indicated airspeed The reverse of the TAS calculation — given a target TAS, returns the IAS you need to fly at a given altitude and temperature. Useful for cruise planning when a performance chart specifies a TAS target.
Wind correction angle & heading Given your true course, true airspeed, wind direction, and wind speed, returns the heading you must fly to track the desired course and the resulting groundspeed. This is the vector wind problem at the core of cross-country navigation.
Fuel burn Calculates fuel required for a given fuel flow and flight time. Supports US gallons and litres. Cross-reference with your aircraft POH fuel tables for the power setting you plan to fly.
Time / speed / distance Solves for any one unknown given the other two — a core skill tested on every pilot written exam. Inputs and outputs support decimal hours, minutes, hh:mm, and hh:mm:ss formats.
Unit converter Converts between aviation units across distance, speed, temperature, pressure, weight, volume, and altitude. Covers knots, mph, km/h, ft/min, inHg, hPa, °C, °F, nautical miles, feet, flight levels, and more.
Frequently Asked Questions
- What does E6B stand for?
- E6B is a US Army Air Corps designation from the 1930s — the "E" denotes a dead reckoning computer, and "6B" is the model variant. The name stuck after the war and is now universally used to refer to any circular slide rule flight computer, physical or digital.
- Do I need an E6B for my pilot written exam?
- Yes. The FAA private pilot, instrument, and commercial written exams all include questions that require an E6B or equivalent — wind correction, time/speed/distance, fuel burn, and density altitude problems. Most testing centres permit a physical E6B or an approved electronic flight computer. Practise with both so you are comfortable under exam conditions.
- Is this E6B flight computer free to use?
- Yes. The E6B flight computer on this page is completely free, runs in your browser, and requires no app or download. All ten calculations — from wind correction to unit conversion — are available without an account.