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Centre Of Gravity (Aircraft) Calculator

Work out centre of gravity (aircraft) instantly with clear inputs, formula shown and shareable results.

About Centre Of Gravity (Aircraft) Calculator

For two loaded stations the centre of gravity sits between them, weighted by mass: CG equals the sum of weight times arm divided by total weight. The result is a moment balance, which is why moving a small weight a long way has the same effect as a large weight moved slightly.

Formula

Two-station CG

CG = (W1 x A1 + W2 x A2) / (W1 + W2)

Worked example

With the default values below, Centre Of Gravity (Aircraft) Calculator returns Centre of gravity of 2.43. Change any input above and every figure here is recalculated in your browser.

Inputs used

Nose or forward station weight
180 kg
Forward station arm
1.4 m
Aft station weight
240 kg
Aft station arm
3.2 m

Results

Centre of gravity
2.43 m
Total weight
420.00 kg
Total moment
1,020.00 kg·m
Share of weight forward
42.9% %

Step by step

  1. 1Values used
  2. 2Two-station CG
  3. 3Centre of gravity= 2.43 m
  4. 4Total weight= 420.00 kg
  5. 5Total moment= 1,020.00 kg·m
  6. 6Share of weight forward= 42.9 %

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

Frequently Asked Questions

How do I express CG as a percentage of MAC?

Subtract the leading-edge MAC arm from the CG, divide by the MAC length and multiply by 100. Transport aircraft loadsheets use %MAC rather than a distance.

Which direction does the CG move when I add aft weight?

Aft. Every added weight pulls the CG toward its own arm, by an amount proportional to the added weight over the new total.

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