Potential Flight Time Calculator

Results

Calculated trip time

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Trip start fuel load

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Full fuel load potential

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(AvGas) load weight

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(Jet A) load weight

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Table of Contents

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What is Potential Flight Time?

This calculator provides simple fuel-endurance arithmetic for an aircraft from tank capacity, an assumed consumption rate and the gallons currently aboard. It reports current-fuel endurance, the current fuel load, endurance at full capacity, and approximate weights for the current quantity using fixed AvGas and Jet A factors.

It is an educational planning check only. It does not subtract unusable fuel or regulatory and personal reserves, and it cannot account for climb, mixture, power, altitude, wind, diversion or changing engine settings. Use approved aircraft information and proper flight planning.

The current-fuel weight outputs can help explain why gallons and pounds should not be interchanged, but they are not a complete weight-and-balance calculation. Fuel location, moment arms, occupants, baggage and aircraft limits all matter. Likewise, a capacity printed for the tanks does not prove that the entered quantity is available to the engine in every attitude or operating condition.

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How to Use This Calculator

  1. Enter total fuel capacity in US gallons.
  2. Enter the expected consumption in gallons per hour, using a figure appropriate to the aircraft and planned operating conditions.
  3. Enter gallons actually in all tanks. This cannot exceed the stated capacity.
  4. Select Calculate. The page reports current endurance, current load, full-capacity endurance and two approximate mass figures.

The result assumes a constant rate. The aircraft flight manual or pilot’s operating handbook is the appropriate source for performance figures and definitions of usable fuel.

3

Formula Used

Current-fuel endurance = current gallons ÷ gallons per hour.

Full-capacity endurance = capacity gallons ÷ gallons per hour.

Approximate AvGas weight = current gallons × 6.00 lb.

Approximate Jet A weight = current gallons × 6.84 lb.

These density factors are fixed approximations on this page. Actual fuel density changes with grade and temperature.

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Variables Explained

Input or valueMeaning
Fuel capacityMaximum gallons entered for the tanks represented. Verify whether the aircraft specification states total or usable capacity.
Consumption ratingExpected burn rate in gallons per hour. It must be greater than zero.
Fuel actually in all tanksCurrent gallons aboard, limited by the entered capacity.
Calculated trip timeIdeal hours supported by current gallons at the constant entered burn rate, before reserves.
Full fuel load potentialIdeal hours at entered capacity and burn rate, before reserves.
Load weightsApproximate pounds for the current gallons using the two fixed fuel factors.
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Worked Example

Enter a 50-gallon capacity, a 10 GPH consumption rate and 40 gallons currently aboard.

Current endurance: 40 ÷ 10 = 4 hours.

Full-capacity endurance: 50 ÷ 10 = 5 hours.

AvGas approximation: 40 × 6.00 = 240 lb.

Jet A approximation: 40 × 6.84 = 273.6 lb.

The page displays 4 hours, 40 gallons, 5 hours, 240 lb and 273.6 lb. None of those time figures includes a reserve.

6

Why Use This Calculator?

Endurance is time supported by fuel at a stated burn rate; it is not flight time to a destination. Distance planning also needs groundspeed, wind and the expected duration of each phase. The FAA explains that pilots should use manufacturer gallons-per-hour figures, consider wind and carry an adequate reserve.

Capacity and current quantity must also be interpreted correctly. Total tank capacity can include unusable fuel, while gauges and visual checks have limitations. A pilot must follow the aircraft documents, operating rules, weather information and personal minimums rather than rely on this page.

If a planned flight contains meaningfully different power settings, prepare a phase-by-phase fuel estimate instead of forcing one average rate to cover everything. Add start, taxi, climb, cruise, descent and contingency quantities using approved information, then check the result against available usable fuel and reserve requirements.

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Common Mistakes

    • Do not plan to consume the calculated final gallon; reserves and unusable fuel are not deducted.
    • Do not use a cruise burn rate for every phase without accounting for start, taxi, takeoff and climb.
    • Current gallons cannot exceed the entered tank capacity.
    • Confirm US gallons rather than imperial gallons, litres or pounds.
    • Fuel weight factors are approximate and should not replace approved weight-and-balance data.
    • Do not confuse endurance hours with distance or arrival fuel.
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Frequently Asked Questions

Does calculated trip time include a reserve?

No. It is current gallons divided by the entered hourly rate. Subtract all required and prudent reserves during proper flight planning.

Why must current fuel be no greater than capacity?

The values describe the same set of tanks, so current gallons cannot logically exceed their entered capacity. Recheck units or capacity if they do.

Where should the burn rate come from?

Use approved aircraft information for the planned power, altitude and operating phase, then account for conditions as proper planning requires.

Is full-fuel potential the same as range?

No. It is an ideal time at a constant rate. Range additionally depends on groundspeed, wind, operating phases and reserves.

Are the AvGas and Jet A weights exact?

No. The page uses fixed 6.00 and 6.84 lb-per-gallon factors. Actual density varies with fuel type and temperature.

Does capacity mean total or usable fuel?

That depends on the aircraft specification. For meaningful endurance, identify usable fuel from approved documents and keep the definition consistent.

Can this replace official preflight planning?

No. It omits many required inputs and checks. Use approved performance data, current weather, applicable rules and sound pilot judgment.

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Sources & References

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