Aircraft Fuel Burn Calculator
Trip fuel is one of the most important numbers in flight planning, and it follows directly from how long you will be airborne and how fast the engine drinks fuel. Time aloft is the leg distance divided by your expected ground speed; trip fuel is that time multiplied by the fuel flow taken from your aircraft's performance charts. This calculator also reports your endurance, the time you could remain airborne on the fuel on board. Enter the fuel flow, distance, ground speed, and fuel on board in consistent units. Always add taxi, climb, reserve, and contingency fuel on top of the cruise burn this tool returns.
Fuel burn formula
Time aloft (hr) = trip distance / ground speed
Trip fuel burn = fuel flow * time aloft
Endurance (hr) = fuel on board / fuel flow
Fuel remaining = fuel on board - trip fuel burn
Units must be consistent: if fuel flow is in gallons per hour, fuel on board and the result are in gallons. Distance is nautical miles and ground speed is knots so the time comes out in hours.
Fuel planning notes
- Cruise fuel flow does not cover taxi and climb; add these from your performance charts.
- Hold back the regulatory reserve (commonly 30 or 45 minutes) before treating fuel as usable.
- Plan against expected ground speed, since headwinds increase both time aloft and trip fuel.
- A negative fuel remaining means the planned leg exceeds fuel on board: refuel or shorten the leg.
- Lean and power settings change fuel flow significantly; use the figure for your actual planned setting.
Fuel burn: frequently asked questions
How do I calculate aircraft fuel burn for a trip?
Divide the trip distance by your ground speed to get the time in hours, then multiply by your fuel flow per hour. The result is the fuel used in flight. Always add taxi, climb, reserve, and contingency fuel separately, because cruise fuel flow alone does not cover those phases.
What is the difference between fuel flow and fuel burn?
Fuel flow is the rate of consumption, in gallons or pounds per hour, taken from your aircraft's performance charts at a given power and altitude. Fuel burn is the total quantity used over a leg, which is fuel flow multiplied by time. This calculator takes the flow you supply and returns the burn.
How is endurance calculated?
Endurance is the time the aircraft can stay airborne on the usable fuel on board, equal to fuel quantity divided by fuel flow. Reduce the usable fuel figure by your required reserve before computing usable endurance, since reserves must remain on landing under the regulations.
What fuel reserves are required?
Under FAA visual flight rules in the day, the regulations require enough fuel to reach the destination and then continue for at least 30 minutes at normal cruise; 45 minutes applies at night and under instrument rules in many cases. Confirm the current requirement in the federal regulations and your operating rules.
Why use ground speed rather than airspeed?
Fuel is burned over time, and the time to cover a distance depends on ground speed, which is your true airspeed adjusted for wind. A strong headwind lengthens the time aloft and increases trip fuel even though airspeed is unchanged, so always plan fuel against the ground speed you expect.
Official sources
- FAA: Pilot's Handbook of Aeronautical Knowledge.
- U.S. Electronic Code of Federal Regulations: 14 CFR fuel requirements.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.