Aviation Fuel Calculator
Fuel required = flight time × fuel burn + taxi + reserve; for example, a 2-hour flight at 9 US gal/h with a 45-minute reserve needs about 25 gallons plus taxi fuel.
For general informational use. Verify critical aviation calculations and weather with an authoritative source.
How a fuel plan is built
Commercial fuel plans split the total into named parts so that each one has a clear purpose. The same structure is a good habit for private flights. The terms below follow ICAO and EASA usage.
| Component | What it covers |
|---|---|
| Taxi fuel | Start-up and taxi before take-off. |
| Trip fuel | Take-off, climb, cruise, descent and approach to the destination. |
| Contingency fuel | Unforeseen factors such as different winds, routing or levels. Commercial operators commonly use a percentage of trip fuel, often 5%, subject to their approved scheme. |
| Alternate fuel | A missed approach at the destination and the flight to the alternate. |
| Final reserve | Fuel that should still be in the tanks on landing. Typically 30 minutes for turbine aircraft and 45 minutes for piston aircraft in ICAO-based rules. |
| Additional and extra fuel | Fuel required for special cases (for example remote routes), and any discretionary fuel the pilot chooses to add. |
Minimum reserves differ between authorities and between VFR and IFR. Compare them side by side in VFR Fuel Reserve Rules and the IFR alternate guide.
Worked example: light single, day VFR (FAA)
- Leg: 180 NM at a groundspeed of 120 kt = 1 h 30 min.
- Fuel flow: 9 US gal/h. Trip fuel: 1.5 × 9 = 13.5 gal.
- Taxi and climb allowance: 1.5 gal.
- Day VFR reserve, 30 minutes at cruise: 4.5 gal.
- Minimum fuel: 13.5 + 1.5 + 4.5 = 19.5 gal, before any extra for weather or headwinds.
Convert gallons to weight for your weight and balance with the Aviation Fuel Weight Converter: avgas is about 6 lb per US gallon.
Fuel traps that catch pilots out
- Unusable fuel counts as weight but not as endurance. Use usable capacity from the flight manual.
- Book fuel flow vs real fuel flow: check your actual burn from the last few flights.
- Headwinds reduce range, not endurance. Endurance is time; the wind decides how far that time takes you.
- Planning to land with exactly the reserve leaves no room for a go-around or holding. Treat the reserve as fuel you should never use.
Planning fuel the conservative way
Fuel exhaustion and starvation remain common causes of general aviation accidents. A simple, written fuel plan shows how much you need for the trip, how much reserve is left at the destination and how long the fuel on board would actually last.
How to use it
- Enter the planned fuel burn per hour and choose gallons or litres.
- Enter the planned flight time in minutes.
- Add taxi and run-up fuel, choose a reserve and an optional contingency percentage.
- Enter usable fuel on board to see endurance and the margin over the minimum.
Method and calculation
Trip fuel = burn × flight time. Contingency = trip fuel × percentage. Reserve fuel = burn × reserve minutes. Minimum fuel required = taxi + trip + contingency + reserve. Endurance = (fuel on board − taxi) ÷ burn. Fuel weight uses about 6.0 lb per US gallon (0.72 kg/L) for Avgas and 6.7 lb per US gallon (0.80 kg/L) for Jet A; actual density varies with temperature.
Worked example and practical notes
A burn of 9 US gal/h for a 95-minute flight needs 14.3 gal trip fuel. Add 1.5 gal taxi, 5% contingency (0.7 gal) and a 30-minute reserve (4.5 gal): about 21 gal minimum. With 40 gal usable on board the endurance is about 4 h 17 min and the margin is about 19 gal.
Accuracy and practical tips
In the US, 14 CFR 91.151 requires enough fuel to reach the first point of intended landing plus 30 minutes by day or 45 minutes at night under VFR; IFR rules (91.167) add an alternate. UK and EASA rules are set differently, so check the regulations and your operator’s policy. Treat legal minimums as the floor, not the plan.
Fuel weights are typical values. Use your aircraft flight manual, actual burn figures and the regulations that apply to your flight.
Last reviewed: October 2026
Read the guide: Aircraft Weight and Balance: Calculating CG
Frequently asked questions
What reserve does the FAA require for VFR?
At least 30 minutes at normal cruise by day and 45 minutes at night, after reaching the first point of intended landing (14 CFR 91.151).
Why add contingency fuel?
Winds, routing, holding and leaning technique all change actual burn. A contingency covers small errors without eating the reserve.
How heavy is Avgas?
About 6 lb per US gallon (0.72 kg per litre). Jet A is heavier at about 6.7 lb per gallon.
Does endurance include taxi fuel?
No. Taxi fuel is subtracted first because it is burned before take-off.