Fuel Burn CG Shift Calculator
Takeoff legal, landing illegal? Compute the CG at takeoff, at landing and at zero fuel in one pass — the three points the envelope must contain.
Removing weight from a station forward of the CG moves the CG aft — the counterintuitive half of the rule. Whether the burn helps or hurts depends entirely on which side of your loaded CG the tanks sit.
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.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Takeoff legal, landing illegal? Compute the CG at takeoff, at landing and at zero fuel in one pass — the three points the envelope must contain.
About Fuel Burn CG Shift Calculator
The envelope must contain the whole flight, not just the first second of it. As fuel burns, the CG migrates toward or away from the tank arm, and aircraft with tanks ahead of the loaded CG can take off legal and land aft of limits. This calculator runs the subtraction form of the moment equation — takeoff condition minus burned fuel — returning landing weight, landing CG, the shift's size and its direction, with the verdict checked against your limits.
How to use Fuel Burn CG Shift 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 CG_landing = (W_to × CG_to − W_fuel × arm_fuel) / (W_to − W_fuel) 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 Burn CG Shift Calculator?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula CG_landing = (W_to × CG_to − W_fuel × arm_fuel) / (W_to − W_fuel) with sources cited on the page
- ✓Removing weight from a station forward of the CG moves the CG aft — the counterintuitive half of the rule. Whether the burn helps or hurts depends entirely on which side of your loaded CG the tanks sit.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
Which way does my CG move as fuel burns?+
Away from the tank, in lever terms: removing weight at a station forward of the current CG shifts CG aft; removing aft weight shifts it forward. Equivalently, the CG migrates toward where the remaining mass sits. If the tank arm equals your loaded CG (many high-wing singles come close), burn barely moves it at all.
Which aircraft genuinely suffer the takeoff-legal/landing-illegal trap?+
Designs with large fuel fractions far from the loaded CG: aft-tank aerobatic types, some canards, certain twins with nacelle/aux tanks, and tip-tank installations with specific burn schedules. Also any aircraft loaded near the aft limit where even a small adverse shift matters. The POH's loading section names the cases — this tool quantifies yours.
Should I check points between takeoff and landing too?+
When either envelope edge slopes with weight, yes: the worst combination of weight and CG can occur mid-burn rather than at the endpoints (a forward limit that relaxes as weight drops, against a CG drifting forward, can pinch in the middle). Run this tool at a mid-fuel state if your envelope's edges aren't vertical.
Does fuel order matter in multi-tank aircraft?+
Materially: burning the aft aux tank first walks the CG forward early; saving tip tanks shifts both CG and structural relief late. POHs and AFM supplements for aux/tip installations prescribe burn sequences for exactly these reasons. Model each phase here with its own tank arm — one pass per tank — to see the trajectory rather than just the endpoints.
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