Useful Load & Full-Fuel Payload Calculator
The numbers that sell airplanes, computed honestly: useful load, full-fuel payload, and the fuel/passenger trade — for any aircraft from two placard values.
Brochure empty weights are optimistic by every radio, tow bar and decade of paint since. Forty years of upgrades typically cost 50–100 lb of the useful load the type certificate promised — weigh, don't believe.
Formula
⚠️ For planning and education only. Weight & balance must be computed from YOUR aircraft's actual empty weight, arm and current equipment list, and verified against the POH/AFM envelope before flight.
The numbers that sell airplanes, computed honestly: useful load, full-fuel payload, and the fuel/passenger trade — for any aircraft from two placard values.
About Useful Load & Full-Fuel Payload Calculator
“Four seats” is a furniture statement, not a loading promise. The honest numbers are useful load (max gross minus your airframe's real empty weight) and full-fuel payload (what remains after the tanks take their 6 lb per gallon) — and for most four-seat singles the second number seats two adults and a duffel. This calculator computes both, then inverts the trade: given your actual occupants, how much fuel fits, and roughly how many hours that buys.
How to use Useful Load & Full-Fuel Payload 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 useful = MTOW − empty; full-fuel payload = useful − 6×gal; fuel possible = (useful − cabin)/6 substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Useful Load & Full-Fuel Payload Calculator?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula useful = MTOW − empty; full-fuel payload = useful − 6×gal; fuel possible = (useful − cabin)/6 with sources cited on the page
- ✓Brochure empty weights are optimistic by every radio, tow bar and decade of paint since. Forty years of upgrades typically cost 50–100 lb of the useful load the type certificate promised — weigh, don't believe.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
What's the difference between useful load and payload?+
Useful load is everything the airframe can lift beyond itself: people, bags AND fuel. Payload is what's left for people and bags after fuel is chosen. A 870-lb useful load with 53 gallons aboard (318 lb) leaves a 552-lb payload — language that matters when a seller quotes the bigger number and your mission needs the smaller one.
Why is my aircraft's empty weight higher than the type's published figure?+
Decades of additions: avionics stacks and their wiring, ADS-B, soundproofing, paint layers, repairs — most of it never removed. Fleet surveys routinely find 50–100 lb of growth over the original spec sheet. The current W&B record after the last reweigh is the only honest number; this tool is only as truthful as that input.
Is the 6 lb-per-gallon fuel weight always right?+
For avgas at standard temperature it's the accepted planning value (true density ≈ 6.01 lb/gal at 15 °C, slightly heavier cold). Jet-A runs ~6.7–6.8 lb/gal — turbine drivers should substitute. The half-percent temperature wiggle is noise next to the brochure-empty-weight error this page keeps warning about.
How should I think about the fuel-vs-payload trade for trip planning?+
Backwards from the mission: fix the people (they're not negotiable), compute permitted fuel here, convert to endurance at your real burn, subtract reserves, and see what leg length survives. If the answer demands a fuel stop, that's a schedule fact, not a defeat — the alternative 'just this once over gross' departs with the worst climb performance on its heaviest day.
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