Fuel Burn & Range Calculator

Frequently Asked Questions

How do I calculate endurance and range?

Endurance (hours) = usable fuel ÷ burn rate. Range (NM) = endurance × TAS. A C172 with 53 gal usable, 8 gph, 115 KTAS: 53 ÷ 8 = 6.6 h × 115 = 760 NM, less reserves.

What reserves do regulations require?

FAR 91.151 (VFR day): land with 30 min fuel at cruise burn; VFR night: 45 min; IFR: alternate fuel + 45 min. Most pilots plan for 1 hour reserve regardless - a 760 NM theoretical range becomes ≈ 645 NM planning range.

How does wind affect range?

Ground speed, not TAS, drives nautical miles covered. A 20 kt headwind on a 115 KTAS aircraft drops GS to 95 kt - range over the ground shrinks from 760 NM to 627 NM at the same fuel burn.

Why use book fuel burn vs actual?

POH burns assume properly leaned mixture, clean airframe, and a healthy engine. Real-world burns often run 5–10% higher; track your own GPH against tach time and adjust planning numbers. Educational only - confirm with POH and current fuel-totalizer data.

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Aviation & Marine Disclaimer: Educational only. Not for flight or navigation operations.

This calculator is for educational and informational purposes only and is not a substitute for official flight or navigation planning. Always use current performance charts, an approved POH/AFM, certified navigation tools, and follow all applicable FAA, ICAO, USCG, and other regulatory guidance. Verify all results independently before operating any aircraft or vessel.

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How This Calculator Works

Fuel planning is non-negotiable: every cross-country flight requires the pilot to compute endurance (how long the tanks will last) and range (how far that endurance carries the aircraft), then subtract a regulatory and personal reserve to confirm the leg is feasible with margin. 14 CFR §91.151 in the US requires 30 minutes of day-VFR reserve and 45 minutes for night or IFR - many pilots add personal margins on top. This calculator takes usable fuel, cruise burn rate, true airspeed, head/tailwind, and reserve in minutes; outputs total endurance, fuel consumed by the reserve, the leg duration after the reserve is set aside, and the range in still air and at the corrected ground speed. Use it for planning study; verify against the POH cruise performance section and current winds aloft before flight.

Formula / Method

Endurance (hours) = usable fuel (gal) ÷ burn rate (gph). Fuel reserved = (reserve minutes ÷ 60) × burn. Usable for leg = total usable − reserve fuel. Leg time = usable-for-leg ÷ burn. Range in still air = leg time × TAS. Range over ground = leg time × ground speed, where GS = TAS ± wind component (use a positive value for tailwind, negative for headwind). Note that range scales linearly with both fuel and TAS but the specific range (nm per gallon) is what changes when you trade altitude or RPM - the calculator assumes a single cruise condition.

Worked Example

Cessna 182 with 75 gal usable, planned cruise burn 13 gph, TAS 140 kt, 20-kt headwind, 45-min IFR reserve. Endurance = 75 ÷ 13 ≈ 5.77 hr. Reserve fuel = 0.75 × 13 = 9.75 gal. Usable for leg = 75 − 9.75 = 65.25 gal, giving leg time 65.25 ÷ 13 ≈ 5.02 hr. Still-air leg range = 5.02 × 140 ≈ 703 nm; with the 20-kt headwind, ground speed is 120 kt, so over-ground range is 5.02 × 120 ≈ 602 nm - do not file a 650-nm leg in this configuration without an enroute fuel stop.

Common Mistakes

Planning to total fuel rather than usable - the unusable quantity in the tanks (often 1–3 gal) cannot be drawn at all attitudes and must never appear in your range math. Forgetting the climb burn - the first 10–15 minutes of every flight burn at a much higher rate; subtract roughly 1 gal extra for a typical light-single climb. Using book TAS without correcting for actual altitude and temperature. Ignoring wind - a 20-kt headwind on a 4-hr leg costs you about 80 nm of range. Mixing units - gallons vs. litres vs. pounds (avgas is ≈6.0 lb/gal, jet-A ≈6.7) is a common source of huge planning errors.

Tips & FAQ

Reserve, regulatory or personal? Many pilots use 60 minutes minimum in good weather, more in IMC or at night. How accurate is the POH burn rate? Within a few percent for a well-leaned engine in cruise; less accurate at full power or rich-of-peak. What about wind aloft? Use the forecast for your cruise altitude, but plan with a margin - winds are often stronger than forecast. Tankering fuel? Extra fuel costs payload and slows the aircraft slightly; balance against fuel price at destination. Disclaimer: this is a planning aid; use the POH/AFM cruise tables, current winds, and a fuel-flow gauge in flight to verify burn matches plan.

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