Aviation Fuel Calculator
Work out how much fuel a flight needs: enter the flight time and fuel burn, add taxi and climb fuel, and choose VFR day, VFR night or IFR reserves. You get the total in gallons, liters and pounds for 100LL or Jet A, plus endurance and the margin over the fuel you have on board.
Last updated:
h:mm, h:mm:ss, or minutes (150)
Gallons or liters per hour, from the POH
Climb fuel above cruise burn, from the POH time-fuel-distance chart
Destination to alternate, h:mm
Extra % of trip fuel for winds, diversions or routing (optional)
To check margin and endurance
How to use the Aviation Fuel Calculator
- Enter the flight time en route as h:mm and the cruise fuel burn per hour.
- Choose the fuel unit and type so the weight uses the right density.
- Add taxi and climb fuel from the POH.
- Pick a reserve rule, add time to the alternate for IFR and any contingency percentage.
- Enter usable fuel on board to see your margin and endurance.
Fuel planning formula
Total fuel = taxi + climb allowance + trip + contingency + alternate + final reserve, where trip = flight time × burn rate, alternate = time to alternate × burn rate, and reserve = reserve minutes ÷ 60 × burn rate.
Worked example (VFR day): 2:30 en route at 9 gal/h gives a trip fuel of 22.5 gal. Taxi 1.4 gal + climb 1.5 gal + trip 22.5 gal + reserve 4.5 gal (30 min) = 29.9 gal, which weighs 29.9 × 6.0 = 179 lb in 100LL. With 40 gal usable on board, the extra fuel is 10.1 gal, about 1:07 of additional flying.
Fuel reserve and density reference
| Rule (US, 14 CFR Part 91) | Minimum reserve | At 9 gal/h | At 14 gal/h |
|---|---|---|---|
| VFR day (91.151) | 30 min after first point of intended landing | 4.5 gal | 7.0 gal |
| VFR night (91.151) | 45 min | 6.75 gal | 10.5 gal |
| IFR (91.167) | Destination + alternate (if required) + 45 min | 6.75 gal + alternate | 10.5 gal + alternate |
| Fuel | lb per US gal | kg per liter | 10 gal weighs |
|---|---|---|---|
| Avgas 100LL | 6.0 | 0.72 | 60 lb (27 kg) |
| Jet A / Jet A-1 | 6.7 | 0.80 | 67 lb (30 kg) |
Fuel planning tips
- Plan to land with more than the minimum. Many pilots and flight schools use a one-hour personal reserve.
- Use real burn rates. Your own logged fuel burn at your usual power setting is more accurate than the book cruise figure.
- Check weight, too. Full fuel may put the airplane over gross weight with passengers; run the weight and balance calculator with the fuel load you choose.
- Re-check in flight. Compare the fuel used with the plan at each checkpoint and divert early if the numbers are going the wrong way.
Frequently asked questions
How do you calculate aircraft fuel required?
Multiply the flight time by the fuel burn to get trip fuel, then add start/taxi fuel, any extra climb fuel, a contingency if you use one, fuel to the alternate for IFR, and the final reserve. For example, 2:30 at 9 gal/h is 22.5 gal; adding 1.4 gal taxi, 1.5 gal climb and a 30-minute VFR day reserve (4.5 gal) gives 29.9 gal.
What are the FAA fuel reserve requirements?
Under 14 CFR 91.151, VFR flights in airplanes need enough fuel to reach the first point of intended landing and then fly for 30 minutes during the day or 45 minutes at night at normal cruising speed. Under 14 CFR 91.167, IFR flights need fuel to the destination, then to the alternate if one is required, then 45 more minutes at normal cruise. These are minimums; many pilots plan an hour.
How much does avgas weigh per gallon?
100LL avgas is planned at 6.0 lb per US gallon (about 0.72 kg per liter). Jet A and Jet A-1 are heavier, about 6.7 lb per gallon (0.80 kg per liter). Actual density changes slightly with temperature.
How do I calculate endurance?
Endurance = usable fuel ÷ fuel burn rate. With 40 gallons usable, 1.4 gallons for taxi and a 9 gal/h burn, the endurance is (40 − 1.4) ÷ 9 ≈ 4.3 hours, or 4:17. That is until the tanks are dry, so always subtract your reserve before planning a flight.
Should I use total or usable fuel?
Use usable fuel, which is listed in the POH. Some fuel in every system cannot be used in flight, so total capacity overstates what you can burn.
Why add climb fuel separately?
Engines burn more fuel at climb power than at cruise. The POH time-fuel-distance to climb chart shows the extra fuel used; adding it gives a more realistic total, especially for short flights or high cruise altitudes.
Does this account for wind?
Only through the flight time you enter. Work out the flight time with the forecast winds first, for example with the E6B flight computer, and add a contingency percentage if winds or routing are uncertain.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.