Fuel Endurance & Range Calculator
Usable fuel into hours aloft and miles covered — with the reserve subtracted first, because endurance to dry tanks is a number for accident reports.
Range rides on ground speed — the same fuel goes 22% further with the wind you fought yesterday. And usable fuel is the POH's number, not the placard's: the difference (unusable) is already spoken for by the certification tests.
Formula
⚠️ For flight planning and education only — verify with official sources, your POH/AFM and certified equipment. Not for primary navigation.
Usable fuel into hours aloft and miles covered — with the reserve subtracted first, because endurance to dry tanks is a number for accident reports.
About Fuel Endurance & Range Calculator
“How long can I stay up?” and “how far can I go?” are one calculation with a discipline attached: subtract the reserve before dividing, not after running dry. This calculator turns usable fuel and flow into protected endurance and range at your ground speed, while displaying the to-the-last-drop figure separately — clearly labeled as the number that belongs in accident reports, not flight plans.
How to use Fuel Endurance & Range Calculator
- 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula endurance = (usable − reserve) ÷ flow; range = endurance × GS substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Fuel Endurance & Range Calculator?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula endurance = (usable − reserve) ÷ flow; range = endurance × GS with sources cited on the page
- ✓Range rides on ground speed — the same fuel goes 22% further with the wind you fought yesterday. And usable fuel is the POH's number, not the placard's: the difference (unusable) is already spoken for by the certification tests.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
What's the difference between usable and total fuel capacity?+
Certification flight testing determines how much fuel can't reliably feed the engine in normal attitudes — trapped in tank corners and lines. A '56 gallon' Skyhawk holds 53 usable; some types trap several gallons per side. The POH's usable figure is the only one endurance math may touch; the placard total includes fuel you own but cannot burn.
Why compute range from ground speed instead of TAS?+
Because the destination is on the ground: the same 4.2 protected hours cover 512 nm at a 122-kt GS but only 420 against a 20-kt headwind. Specific range (nm per gallon) inherits the wind the same way — which is why maximum-range strategy in wind shifts speed slightly (faster into headwinds, slower with tailwinds).
How should I set the reserve input?+
At your personal minimum, not the legal one: 60 minutes is the most common professional habit for piston GA (the regulation's 30/45 assumes nothing else goes wrong). Fuel exhaustion remains a leading cause of entirely preventable accidents, and nearly every case flew through the moment this calculator's protected endurance hit zero.
My gauges disagree with this math — which wins?+
The math, fed by a visual/dipstick quantity check before takeoff and a clock in flight. Light-aircraft gauges are required to be accurate only at empty; time-times-flow with a known starting quantity outperforms them decisively. The professional loop: dip the tanks, log the time, fly the flow you've validated, and treat the gauges as a cross-check that may only make the picture worse, never better.
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