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Centre of Gravity Fuel Burn-Off Calculator

Check that the aircraft centre of gravity stays within limits from takeoff through to fuel exhaustion.

Last reviewed by the myCalculator Editorial Team

Input Parameters

kg
mm
kg
mm
L
L
mm
kg/L

AvGas 100LL is 0.72 kg/L; Jet A-1 is 0.80 kg/L.

mm
mm

Calculation Results

Takeoff CG Position
2172.3 mm ✅ IN LIMITS
Zero-Fuel CG Position
2178.4 mm ✅ IN LIMITS
CG Shift During Fuel Burnoff
6.1 mm AFT shift
Takeoff Weight (TOW)
1388 kg
Zero-Fuel Weight (ZFW)
1280 kg
Fuel Mass
108 kg (150L × 0.72 kg/L)
CG Envelope Forward Limit
2050 mm
CG Envelope Aft Limit
2340 mm
Summary: Takeoff CG: 2172.3mm (WITHIN limits). As 108kg of fuel burns off, CG migrates 6.1mm AFT shift to 2178.4mm ZFW (WITHIN limits).
Step-by-Step Calculation Solution
1.Fuel Mass = 150L × 0.72 kg/L = 108 kg
2.Takeoff Weight = BEW (1000kg) + Payload (280kg) + Fuel (108kg) = 1388 kg
3.Takeoff Total Moment = (1000×2150) + (280×2280) + (108×2100) = 3,015,200 kg·mm
4.Takeoff CG = Total Moment / TOW = 3,015,200 / 1388 = 2172.3 mm
5.ZFW Total Moment = (1000×2150) + (280×2280) = 2,788,400 kg·mm
6.ZFW CG = 2,788,400 / 1280 = 2178.4 mm
7.CG Shift = ZFW CG - Takeoff CG = 2178.4 - 2172.3 = 6.1 mm (AFT shift)

Formula & How Centre of Gravity Fuel Burn-Off Calculator Works

Mathematical Formula
CG = Σ(Weight × Arm) / Σ(Weight) | Check CG at takeoff weight and at zero-fuel weight

Centre of gravity moves during flight as fuel burns off, because removing weight at the fuel arm shifts the overall moment. A loading that is legal at takeoff can drift outside the aft limit by the end of the flight if the fuel tanks sit forward of the CG, or outside the forward limit if they sit aft. CASA requires the CG to remain within the certified envelope for the entire flight, so both the takeoff and zero-fuel conditions must be checked.

How to Calculate Centre of Gravity Fuel Burn-Off Calculator (Step-by-Step)
  1. Enter Basic Empty Weight (kg) (kg): Input your target parameter value.
  2. Enter Empty Weight CG Arm (mm from datum) (mm): Input your target parameter value.
  3. Enter Payload — Crew, Pax & Baggage (kg) (kg): Input your target parameter value.
  4. Enter Payload CG Arm (mm from datum) (mm): Input your target parameter value.
  5. Enter Usable Fuel Capacity (L) (L): Input your target parameter value.
  6. Enter Fuel Loaded (L) (L): Input your target parameter value.
  7. Enter Fuel CG Arm (mm from datum) (mm): Input your target parameter value.
  8. Enter Fuel Density (kg/L) (kg/L): Input your target parameter value.
  9. Enter Forward CG Limit (mm) (mm): Input your target parameter value.
  10. Enter Aft CG Limit (mm) (mm): Input your target parameter value.
  11. Apply Formula: Calculate using CG = Σ(Weight × Arm) / Σ(Weight) | Check CG at takeoff weight and at zero-fuel weight.
  12. Review Results: View exact computed answers, metrics, and worked mathematical proofs.
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Frequently Asked Questions (FAQs)

Why does the centre of gravity move as fuel burns?

Fuel is stored at a fixed arm from the datum. Removing that weight changes the total moment, so the CG shifts away from the fuel arm as the tanks empty.

Which CG condition is most critical?

Both must be checked. Takeoff is usually the forward-limit case at maximum weight, while zero-fuel is usually the aft-limit case — an aft CG reduces longitudinal stability and stall recovery margin.

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Official Regulatory & Government Data Sources

Authoritative Standards & Verified Reference Citations

Independent & Verified

Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:

Civil Aviation Safety Authority (CASA)Government
Australian Government Statutory Authority

CASR Part 91 general operating and flight rules, Part 121 fuel reserves, and flight crew licensing standards.

www.casa.gov.au
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