Endurance Calculator
Find out how long your aircraft can stay airborne from its usable fuel and fuel flow. Switch to reserve-adjusted mode to protect an FAA fuel reserve and see your safe flying time. Supports US gallons, Imperial gallons, liters, and pounds.
Fuel flow must be in gal/hr to match US gal of fuel.
Why This Matters to Pilots
Endurance versus range: endurance is how long you can stay in the air; range is how far you can travel. A headwind reduces your range but does not change your endurance — you still burn the same fuel per hour, you just cover less ground. This distinction matters when you are holding, diverting, or waiting for weather to improve.
Fuel exhaustion is a leading cause of general aviation accidents. Knowing your endurance before departure is a fundamental preflight task, not an in-flight guess.
Fuel flow varies with altitude, power setting, and mixture. Use the fuel flow from your POH cruise performance tables for the planned altitude and power setting, not the maximum fuel flow.
Limitations
This calculator assumes constant fuel flow throughout the flight. Actual fuel flow varies during climb, cruise, and descent. Taxi fuel is not included — subtract taxi fuel from usable fuel before entering it here. Always verify fuel quantity visually before flight.
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Frequently Asked Questions
This calculator is for educational and planning purposes only. Always refer to your aircraft's POH/AFM, current NOTAMs, and official weather briefings. No calculator is a substitute for pilot-in-command judgment or CFI guidance. Read our full Safety Disclaimer.
Last reviewed: July 2026
Endurance in Depth
Endurance is the total time an aircraft can remain airborne on a given quantity of fuel, and it answers a different question than range. Range asks how far you can go; endurance asks how long you can stay up. The distinction matters for holding, for weather delays, for search patterns, and any time the clock rather than the distance is the binding constraint. This calculator turns usable fuel and burn rate into a clear time figure.
Because endurance is measured in time, it is the natural language of fuel reserves, which the regulations express in minutes of flight, not miles. A pilot who thinks in endurance terms instinctively understands that slowing down to a more economical power setting buys more airborne time from the same fuel, even though it does not always buy more distance over the ground.
Step-by-Step: How the Calculation Works
Endurance equals usable fuel divided by fuel burn rate. Fifty gallons usable at 10 gallons per hour gives five hours of engine running time. From that gross figure you subtract the fuel used for taxi and the reserve you intend to land with, leaving the endurance actually available for the mission.
The burn rate to use depends on the power setting. Maximum-endurance flying uses the lowest practical power that maintains safe flight, which minimizes gallons per hour and maximizes time aloft. This is a different setting than maximum-range flying, which optimizes distance per gallon. The calculator lets you enter the burn rate matching whichever objective you are planning for.
More Worked Examples
Example 1 — Total endurance
With 40 gallons usable and a cruise burn of 8 gallons per hour, gross endurance is 5.0 hours. Set aside 45 minutes of VFR reserve and roughly 15 minutes for taxi and climb, and about 4.0 hours remain for the planned flight.
Example 2 — Endurance for holding
You expect a possible 30-minute delay at your destination. Reducing to a holding power setting that burns 6 gallons per hour instead of 9 stretches the same 12 reserve gallons from about 1.3 hours to 2.0 hours of holding capability — a meaningful margin if the delay grows.
Pilot Decision-Making Context
Endurance thinking is central to reserve discipline. Because the regulations require you to land with a set number of minutes of fuel remaining, planning in time keeps you aligned with the rule directly rather than translating awkwardly from distance. When a headwind slows your groundspeed, your range shrinks but your endurance does not — a distinction that keeps you from panicking over a number that has not actually changed.
Endurance also frames diversion decisions. If weather stalls your arrival, the relevant question is how many minutes of flying you have left, not how many miles, and a pilot who has computed endurance can make that call cleanly. Slowing to a maximum-endurance setting is a legitimate tool for buying time while a situation resolves.
More Questions Answered
Is maximum endurance the same as maximum range?
No. Maximum endurance minimizes fuel burned per hour to stay aloft longest, while maximum range maximizes distance flown per gallon. They occur at different airspeeds and power settings.
Does a headwind reduce my endurance?
No. Wind changes how far you travel over the ground but not how long the engine can run on the fuel aboard. Endurance depends on fuel quantity and burn rate alone.
How does weight affect endurance?
A heavier aircraft requires more power to maintain level flight, which raises the burn rate and slightly reduces endurance. Burning off fuel during a long flight gradually improves the burn rate as the aircraft lightens.
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