Aviation Calculators
Fuel endurance.
Endurance is fuel on board divided by fuel burn per hour. Enter your fuel, burn rate and ground speed, choose a reserve, and get total and usable endurance, range, and the fuel needed for a trip. Use the same unit for fuel and burn. Runs in your browser; nothing is sent or stored.
Planning aid, not for flight operations
This tool is for study, trip planning and curiosity. It is not approved flight-planning or performance data. For an actual flight, use the aircraft's approved Pilot's Operating Handbook or Aircraft Flight Manual, current weather and charts, and your own judgement as pilot in command. Results can differ from your aircraft's real figures.
Inputs
Result
Fill the form and press Calculate.
Worked example
40 gallons on board, a burn of 9.5 gallons per hour and a ground speed of 110 knots. Total endurance is 40 ÷ 9.5 = 4.21 hours (4 h 13 min). A 30 minute reserve takes 4.75 gallons, leaving 35.25 usable gallons, or 3.71 hours and 408 nautical miles of range. A 200 nautical mile trip takes 1.82 hours and 17.3 gallons; with the reserve you need 22.0 gallons, leaving 18.0 gallons spare. The 40 gallons weigh 240 lb at 6 lb per gallon.
How it works
Endurance = fuel ÷ burn rate. The reserve fuel is burn rate × reserve minutes ÷ 60. Usable fuel is fuel minus reserve, usable endurance is usable fuel ÷ burn rate, and range = usable endurance × ground speed. For a trip, trip time = distance ÷ ground speed, trip fuel = trip time × burn rate, and required fuel = trip fuel + reserve.
The FAA handbook's own example is a 400 NM flight at 100 knots ground speed taking 4 hours; at 5 gallons per hour that is 20 gallons, and it says to use ground speed when wind is present. The 30 and 45 minute choices follow the US rule for airplanes under VFR (14 CFR 91.151): enough fuel to fly to the first point of intended landing and then, at normal cruising speed, at least 30 minutes by day or 45 minutes at night. Other countries and other kinds of flight have different reserve rules, so check the rules that apply to you. Use the Custom option for those.
Sources (each opened 2026-10-08): FAA, Pilot's Handbook of Aeronautical Knowledge, Chapter 16: Navigation; FAA, Pilot's Handbook of Aeronautical Knowledge, Chapter 10: Weight and Balance; eCFR, 14 CFR 91.151, Fuel requirements for flight in VFR conditions.
FAQ
How do I calculate fuel endurance?
Divide the usable fuel by the fuel burn per hour. For example, 40 gallons at 9.5 gallons per hour is about 4.2 hours before any reserve.
What fuel reserve is required for VFR?
Under US rule 14 CFR 91.151, an airplane flying VFR must have enough fuel to reach the first point of intended landing and then, at normal cruising speed, fly at least 30 minutes by day or 45 minutes at night (20 minutes for a rotorcraft). Other countries set their own reserves.
Should I use airspeed or ground speed?
Ground speed. The FAA handbook says fuel consumption stays relatively constant at a given true airspeed, so with wind you must use ground speed to work out how much fuel a trip needs.
How much does aviation fuel weigh?
The FAA handbook gives gasoline as about 6 pounds per gallon. Enter your own value if you use another fuel or unit. Weight is only shown if you enter a figure.
Does this account for climb, taxi or headwind changes?
No. It uses the single burn rate and ground speed you enter. Add taxi, climb and any contingency fuel yourself, and recompute if the wind changes.
Is this a flight plan?
No. It is a learning and planning aid. Use your aircraft's approved fuel data, current weather and your own judgement; when in doubt, carry more fuel.