Gallons Per Hour Consumption Calculator

Results

Consumption Rate

0

Fuel Used

0

Starting-Fuel Endurance

0

Full Fuel Load Potential

0

Trip Start Fuel (AvGas)

0

Trip Start Fuel (Jet A)

0

Table of Contents

1

What is Gallons Per Hour Consumption?

This calculator estimates average fuel burn in US gallons per hour from starting fuel, ending fuel, and elapsed operating time. It also reports the amount used, theoretical endurance at the same burn rate, and approximate starting-fuel weights for aviation gasoline and Jet A. These figures are useful for reviewing a completed interval and making rough comparisons.

They are not a substitute for an aircraft’s approved flight manual, fuel gauges, calibrated fuel-flow equipment, required reserves, or preflight planning. Fuel burn changes with engine setting, altitude, mixture, taxi time, weather, phase of flight, and aircraft condition. The endurance figures assume the observed average rate continues and do not subtract any legal or prudent reserve.

2

How to Use This Calculator

  1. Enter usable tank capacity, elapsed trip time in decimal hours, fuel at the start, and fuel remaining at the end. All fuel quantities must be US gallons.
  2. The page subtracts ending fuel from starting fuel to find fuel used, then divides by elapsed hours to obtain average gallons per hour.
  3. It divides starting fuel and full capacity by that rate to show theoretical endurance. It also estimates starting-fuel weight using 6.0 lb/US gal for Avgas and 6.7 lb/US gal for Jet A.

Convert minutes to a decimal fraction of an hour: 30 minutes is 0.5 hour, while 1 hour 30 minutes is 1.5 hours. Starting fuel cannot exceed capacity, and ending fuel cannot exceed starting fuel. If no measurable fuel was used, a burn rate of zero is returned and endurance is shown as unavailable rather than dividing by zero.

3

Formula Used

Fuel used = starting gallons − ending gallons

Average GPH = fuel used ÷ elapsed hours

Theoretical endurance = available gallons ÷ average GPH

Approximate starting fuel weight is starting gallons × 6.0 lb for Avgas or × 6.7 lb for Jet A. These convenient density factors are approximate; actual density varies with grade, composition, and temperature. “Full-fuel potential” uses entered tank capacity. Neither endurance value subtracts unusable fuel, reserve fuel, or fuel allocated to taxi and contingencies unless those have already been removed from the gallons entered.

4

Variables Explained

Entry or resultMeaningImportant boundary
Fuel capacityMaximum gallons represented in the full-tank comparison.Use usable capacity for planning context.
Elapsed tripMeasured operating time in decimal hours.Must be greater than zero.
Starting fuelGallons available at the beginning.Cannot exceed entered capacity.
Ending fuelGallons remaining after the interval.Cannot exceed starting fuel.
Consumption rateAverage gallons used per hour.Not necessarily the rate in every flight phase.
EnduranceGallons divided by the observed average rate.Theoretical time with no reserve deduction.
5

Worked Example

An aircraft has a 50-gallon usable capacity, begins an observed interval with 40 gallons, ends with 28 gallons, and operates for 2.0 hours. Fuel used is 40 − 28 = 12 gallons. Average consumption is 12 ÷ 2 = 6 GPH. At that unchanged rate, 40 gallons represents 6.67 hours and 50 gallons represents 8.33 hours of theoretical endurance.

The approximate starting fuel weights are 40 × 6.0 = 240 lb for Avgas and 40 × 6.7 = 268 lb for Jet A. These are reference estimates, not interchangeable fuel approvals. The aircraft must use its approved fuel type and its approved weight-and-balance data.

6

Why Use This Calculator?

Average GPH describes the entire measured interval. It can hide a high climb burn and a lower cruise burn, so do not assume each phase used fuel at that exact rate. Compare repeated results only when timing conventions and measured gallons are reasonably consistent. Unexpected changes deserve investigation rather than being treated as ordinary calculator noise.

The endurance outputs are mathematical quotients, not safe time aloft. Actual planning must account for usable fuel, required reserves, route, forecast conditions, alternate needs, taxi, mixture, power setting, and official performance information. Approximate fuel weights can assist a quick reasonableness check, but the aircraft’s approved data and actual fuel specifications govern weight and balance.

7

Common Mistakes

    • Subtracting elapsed hours from gallons; quantities with different units cannot be subtracted.
    • Entering one hour thirty minutes as 1.30 hours instead of 1.5 hours.
    • Using tank capacity as though it were the measured fuel burned.
    • Treating theoretical endurance as usable flight time without reserves.
    • Using total tank volume when part of the fuel is unusable.
    • Assuming the approximate Avgas or Jet A weight factor is exact at every temperature.
    • Using the average from one flight without checking whether power setting and operating conditions are comparable.
8

Frequently Asked Questions

How do I enter hours and minutes?

Convert minutes to a fraction of 60. For example, 45 minutes is 0.75 hour, so 2 hours 45 minutes is entered as 2.75.

Is gallons per hour the same throughout a flight?

Usually not. Taxi, takeoff, climb, cruise, and descent may have different rates. This result is the average over the entered interval.

Does the endurance result include a fuel reserve?

No. It is gallons divided by the observed rate. Required and prudent reserves must be handled in formal planning.

Why can ending fuel not exceed starting fuel?

This page models consumption during one interval without refueling. A larger ending amount indicates a data-entry error or a refueling event that needs a different calculation.

Are the fuel weight figures exact?

No. The page uses convenient approximate factors of 6.0 lb/US gal for Avgas and 6.7 lb/US gal for Jet A. Actual density varies.

What happens when no fuel was used?

The average rate is zero, but endurance cannot be obtained by dividing by zero, so the page reports endurance as unavailable.

Can this result replace official aircraft performance data?

No. Use the approved flight manual, actual fuel information, regulations, and appropriate preflight planning for operational decisions.

9

Sources & References

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