Flight Time, Wind & Fuel Calculator
Enter route distance, course, true airspeed, forecast wind, fuel burn, reserve, and usable fuel. The calculator returns the wind correction, groundspeed, en-route time, fuel required, and the surplus or shortfall onboard.
Minimum departure fuel (gal)27.04
- Wind correction angle
- 0 degrees
- True heading (° true)
- 90
- Headwind or tailwind component
- 20 kt tailwind
- Groundspeed (kt)
- 140
- Estimated en-route time
- 2 hr 9 min
- En-route fuel (gal)
- 19.29
- Reserve fuel (gal)
- 6.75
- Fuel margin (gal)
- 7.96
- Fuel status
- Usable fuel covers the calculated minimum by 8 gal.
Uses one constant true course, true airspeed, wind, and cruise fuel burn for the en-route segment.
Taxi fuel is included in the minimum departure fuel; climb, descent, alternates, contingencies, and fuel unusable by the aircraft are not modeled unless you include them in the inputs.
How to use this calculator
- Enter the planned route distance and true course for the leg or route segment.
- Enter cruise true airspeed and the forecast wind direction and speed at altitude.
- Add cruise fuel burn, taxi fuel, reserve minutes, and usable fuel onboard.
- Read the wind-corrected heading, groundspeed, en-route time, minimum departure fuel, and margin.
How the flight estimate is calculated
This calculator treats the route as one straight en-route segment flown at one true airspeed with one forecast wind. Wind direction is entered as the direction the wind is from, using the same true reference as the course. The wind triangle first separates the wind into a crosswind component and a headwind or tailwind component, then uses those values to solve heading, groundspeed, time, and fuel.
Let D be distance in nautical miles, C true course, A true airspeed in knots, W wind-from direction, V wind speed, B cruise fuel burn in gallons per hour, T taxi fuel, R reserve minutes, and F usable fuel onboard. The wind angle is delta = (W - C). The crosswind component is X = V x sin(delta), and the headwind component is H = V x cos(delta). A negative H is a tailwind.
The wind correction angle is theta = asin(X / A). A negative angle means correct left of course, and a positive angle means correct right. True heading is normalize(C + theta), wrapping around 0 and 359 degrees. Groundspeed is G = A x cos(theta) - H. En-route time is E = D / G hours.
Fuel is then a time calculation. En-route fuel is Q = E x B. Reserve fuel is Qr = (R / 60) x B. Minimum departure fuel is M = T + Q + Qr. The margin shown at the end is F - M, so a negative value is a shortfall rather than a surplus.
What changes the result most
Headwind and tailwind change en-route time directly because they change groundspeed along the course. Crosswind changes heading and slightly reduces the along-track part of the aircraft's airspeed. Fuel burn then multiplies whatever time the wind creates, so a slow groundspeed and a high burn rate compound quickly.
What this calculator leaves out
The estimate does not model climb, descent, step climbs, mixture changes, altitude changes, routing amendments, holding, alternates, contingency fuel, unusable fuel, or forecast uncertainty. Include any allowance you want for those items by increasing taxi fuel, reserve minutes, route distance, or another input as appropriate. The result is a planning estimate, not an approved flight plan or aircraft performance calculation.
Worked example
Suppose a 300 NM route is flown on a true course of 090 degrees at 120 kt true airspeed. The wind is from 270 degrees at 20 kt, cruise fuel burn is 9 gal/hr, taxi fuel is 1 gal, reserve is 45 minutes, and usable fuel onboard is 35 gal.
The wind is a 20 kt tailwind with no crosswind component, so the wind correction angle is 0 degrees and the true heading remains 090 degrees. Groundspeed is 120 + 20 = 140 kt. Time is 300 / 140 = 2.1429 hours, or about 2 hr 9 min.
En-route fuel is 2.1429 x 9 = 19.29 gal. Reserve fuel is 45 / 60 x 9 = 6.75 gal. Minimum departure fuel is 1 + 19.29 + 6.75 = 27.04 gal, leaving about 7.96 gal of margin from 35 gal onboard.
Common questions
How do wind direction and wind speed change flight time?
A headwind lowers groundspeed and increases flight time. A tailwind raises groundspeed and lowers flight time. A crosswind mainly changes the heading needed to hold the course, with a smaller effect on groundspeed because some airspeed is spent correcting sideways drift.
What is the difference between true airspeed and groundspeed?
True airspeed is the aircraft speed through the surrounding air mass. Groundspeed is the speed over the ground after wind is applied. Fuel burn in cruise is tied to time aloft, so groundspeed is the value used to turn route distance into en-route time.
How is wind correction angle calculated?
The calculator finds the signed crosswind component from the angle between the wind-from direction and the course. It divides that crosswind by true airspeed and takes the arcsine. The sign shows whether the heading correction is left or right of the planned course.
Why must course and wind direction use the same reference?
The wind triangle only works when both directions are measured from the same north reference. This page uses true course and true wind direction. If you mix magnetic course with true wind, the wind angle will be wrong by roughly the local variation.
How much reserve fuel should I enter?
Enter the reserve required for the aircraft, operation, route, weather, and rules that apply to the flight. The calculator simply converts reserve minutes into fuel at the entered cruise burn rate. It does not decide whether a reserve is legally or operationally adequate.
Why can a strong crosswind make the course impossible to hold?
Holding a ground track requires enough sideways airspeed to cancel the crosswind. If the crosswind component equals or exceeds true airspeed, the wind correction angle would be 90 degrees or more. At that point there is no practical forward course solution for this model.