Educational calculators only. Not for operational flight planning.

Fuel Consumption Calculator

Fuel flow figures in a flight manual are predictions; this calculator works backwards from what actually happened. Enter the fuel a flight used and the time it took, and it returns the average burn per hour and per minute. Add the distance covered and it also gives fuel per nautical mile, specific range and the average ground speed.

Comparing an observed average with the figure that was planned is one of the plainest ways to see how power setting, altitude, leaning and wind show up in a fuel log. The result describes one flight under one set of conditions. It is a record to learn from, not a planning value for the next flight.

Inputs

Time flown
hmin

Optional. Adds fuel per distance.

Results

Enter your values and select Calculate.

Educational use only. Results are not certified for operational flight planning or aircraft performance decisions. Always use approved aircraft documentation and official aviation information before flight.

How to use this calculator

  1. Enter Fuel used and choose US gallons, liters, imperial gallons, pounds or kilograms.
  2. Enter Time flown in hours and minutes.
  3. Optionally enter Distance flown in nautical miles, kilometers or statute miles to add the per-distance rows.

Fuel used should be a measured quantity from your own records, such as the amount added to bring the tanks back to the level they started at, not a figure from a handbook. The time has to cover the same period as the fuel: if the fuel includes start, taxi and climb, so must the time, or the hourly figure will be overstated. The minutes box takes 0 to 59, so two and a half hours is 2 hours 30 minutes.

Formula

fuel flow = fuel used ÷ time

fuel per distance = fuel used ÷ distance

specific range = distance ÷ fuel used

What the variables mean

fuel used
fuel actually burned, by volume or by mass
time
elapsed time in hours
distance
distance flown, if you want fuel per nautical mile

Worked example

These example values are illustrative round numbers, not data for any particular aircraft. Select "Fill in the example" in the calculator to load them.

Inputs

  • Fuel used: 21.5 US gal
  • Time flown: 2 h 30 min
  • Distance flown: 290 NM

Working

  1. Time = 2.500 h.
  2. Fuel flow = 21.50 ÷ 2.500 = 8.60 US gal/h.
  3. Fuel per NM = 21.50 ÷ 290.0 = 0.074 US gal/NM.

Result

  • Average fuel flow: 8.60 US gal/h (32.55 L/h · 7.16 imp gal/h)
  • Fuel per minute: 0.143 US gal/min
  • Fuel per nautical mile: 0.074 US gal/NM
  • Specific range: 13.49 NM per US gal
  • Average ground speed: 116.0 kt

Reading the result

Average fuel flow is in the unit you chose per hour, with the other units of the same kind beside it: volume stays volume and mass stays mass. Fuel per minute is the same rate divided by 60. With a distance entered, Fuel per nautical mile and Specific range are two views of one ratio, and Average ground speed is simply distance divided by time, which makes it a useful sanity check on your inputs. For illustration, 21.5 US gal over 2 h 30 min and 290 NM gives 8.60 US gal/h and 13.49 NM per US gal.

Assumptions and limitations

  • The result is one average over the whole period, so taxi, climb, cruise and descent are blended together.
  • Volume is never converted to mass or mass to volume, because that needs the density of the actual fuel at its actual temperature.
  • Distance is treated as distance over the ground, so the per-mile figures carry the effect of whatever wind was present.
  • The average ground speed row includes any time on the ground that is part of the time you entered.
  • The answer is only as accurate as the fuel measurement behind it; dipsticks, gauges and pump meters all have tolerances.
  • Nothing here predicts fuel flow at another weight, altitude, temperature or power setting; planning figures come from the aircraft flight manual.

Common mistakes

  • Dividing fuel for the whole flight by airborne time only, or cruise fuel by block time.
  • Treating the average as the cruise fuel flow when it also contains the climb and ground running.
  • Carrying an average from one flight into the planning of another flown at a different altitude, power setting or weight.
  • Noting the refuel in liters and entering the number with US gallons selected.
  • Comparing fuel per nautical mile between two flights without allowing for the different winds.
  • Entering 2.5 hours as 2 hours 50 minutes instead of 2 hours 30 minutes.

References

  1. Federal Aviation Administration, Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25).

These public sources explain the formulas and definitions used here. Citing them does not mean they have reviewed, endorsed or certified AviationCalc.

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