Fuel Endurance & Range Calculator

Endurance is how long the engine can run on the fuel you have. Range is how far that takes you over the ground. Both depend on the fuel burn per hour, which changes with power setting, altitude, mixture and weight, so use the cruise figure from your aircraft's manual and plan with a margin.

The formula

usable fuel = fuel on board − unusable fuel
endurance (hours) = usable fuel ÷ fuel burn per hour
range = endurance × ground speed
trip fuel = trip time × burn per hour  (trip time = distance ÷ ground speed)
reserve fuel = reserve minutes ÷ 60 × burn per hour
minimum fuel = taxi + trip + contingency + alternate + final reserve + extra
extra fuel (or shortfall) = usable fuel − minimum fuel
point of no return time = safe endurance × GS home ÷ (GS out + GS home)
equal time point = distance × GS back ÷ (GS on + GS back), measured from departure

Worked example

You have 40 US gallons on board, burn 9 US gallons an hour and fly at a ground speed of 110 kt. The endurance is 40 ÷ 9 = 4.44 hours, which is 4 h 27 min. The range is 4.444 × 110 = 489 nm to dry tanks. You use 9 ÷ 110 × 100 = 8.18 gallons per 100 nm, and 9 ÷ 60 = 0.15 gallons a minute.

Now plan a 300 nm trip (the Advanced example). The trip takes 300 ÷ 110 = 2.727 hours (2 h 44 min) and burns 2.727 × 9 = 24.545 gallons. Add 1 gallon of taxi fuel, 5% contingency (24.545 × 0.05 = 1.227 gallons) and a 45-minute final reserve (0.75 × 9 = 6.75 gallons). The minimum is 1 + 24.545 + 1.227 + 6.75 = 33.52 gallons, so with 40 on board you have 6.48 gallons extra, about 43 minutes of flying. You would land with 40 − 1 − 24.545 = 14.45 gallons.

Keeping the taxi fuel and final reserve aside leaves 40 − 1 − 6.75 = 32.25 gallons to fly on: 3 h 35 min. With no wind the point of no return is half of that, 1 h 47.5 min or 197 nm out, and the equal time point on the 300 nm trip is halfway, 150 nm.

A fuel plan, line by line

• Taxi: fuel for start-up, run-up and taxi before take-off.
• Trip: take-off to landing at the destination. Climbs burn more than cruise, so some pilots add a climb allowance here or in "extra".
• Contingency: a cover for things that don't go to plan, such as stronger headwinds or a longer route. Often a percentage of the trip fuel, sometimes with a minimum in minutes.
• Alternate: fuel to fly from the destination to an alternate airport if you can't land.
• Final reserve: fuel that should still be in the tanks when you land. Planning to use it is not planning.
• Extra: holding for weather or traffic, or fuel the pilot in command chooses to add.

Reserve rules are different everywhere

This calculator does not apply any country's law; you choose the reserves. As examples only: under US FAA rules (14 CFR 91.151) VFR flights in aeroplanes plan to land with at least 30 minutes of fuel by day and 45 minutes at night, and IFR flights (91.167) need fuel to the destination, then the alternate if one is required, plus 45 minutes. EASA commercial air transport fuel schemes commonly use a contingency of 5% of trip fuel and a final reserve of 30 minutes for jets and 45 minutes for piston aircraft. Operators often add more. Check the current rules of your own authority and operator.

Point of no return and equal time point

The point of no return (PNR) is the furthest you can fly out and still get back to where you started with your reserves intact. Here it uses the fuel left after taxi and with the alternate, final reserve and extra kept aside. A headwind on the way out means a tailwind on the way back, so you spend longer flying out but cover less ground: the PNR moves closer to home.

The equal time point (ETP, or critical point) is where carrying on to the destination takes the same time as turning back. With a headwind on the way out, it moves towards the destination. It is used for planning what to do after an engine failure or medical emergency over water or remote ground. Airline ETPs often use a different speed and fuel burn for the failure case; you can enter those speeds yourself.

Units

1 US gallon = 3.785 litres. 1 imperial gallon = 4.546 litres. 1 lb = 0.4536 kg. To go between volume and weight you need the density: avgas 100LL is about 0.72 kg per litre (6.0 lb per US gallon) and Jet A-1 about 0.80 kg per litre (6.7 lb per US gallon), and it changes with temperature. Use the figure on your fuel receipt if you have it.

For planning and training only. Always use your aircraft's flight manual figures, check the fuel visually before flight and follow your authority's and operator's rules. Checked 10 October 2026.