Weight & Balance Calculator
Load a C152/C172/PA28/DA40, get CG, ramp/takeoff/landing weights, and an envelope check.
Inputs
Result
Center of gravity
42.4in
Within the certified envelope
Ramp weight
Max 2,558 lb
2,440lb
Takeoff weight
MTOW 2,550 lb
2,432lb
Landing weight
2,312lb
Zero-fuel weight
2,200lb
Total moment
103,420lb·in
CG 42.4 in at 2,440 lb — within limits
Formula
Ref- Moment = Σ (weight × arm)
- CG = total moment ÷ total weight
- In limits ⇔ (CG, weight) inside the certified envelope
Worked example
RefCessna 172S: empty 1680 lb @ 39.0 in, 340 lb front, 170 lb rear, 30 lb baggage, 40 gal fuel.
- 1.Moment = Σ(weight × arm) for empty + occupants + baggage + fuel.
- 2.Ramp weight = 1680 + 340 + 170 + 30 + (40 × 6.0) = 2460 lb.
- 3.CG = total moment ÷ ramp weight.
- 4.Plot (CG, weight) against the C172 envelope polygon.
CG within the certified envelope at 2460 lb ramp — safe to fly.
How it works
RefWeight and balance confirms the aircraft is both under its maximum weights and loaded so the centre of gravity sits inside the certified envelope. Each item's weight times its arm is a moment; summed and divided by total weight gives the CG. A CG too far forward or aft degrades stability and control, so the envelope check is as important as the weight check.
DGCA student tip
ExamThe moment method (weight × arm) and the CG envelope plot are DGCA staples. Remember ramp weight includes taxi fuel; takeoff weight is ramp minus taxi fuel; landing weight is takeoff minus trip fuel. An aft CG is often the sneakier limit in loading questions.
Common mistakes
Watch- Checking only total weight and forgetting the CG envelope.
- Using pounds for weight but the arm in the wrong reference datum.
- Forgetting to subtract taxi and trip fuel for takeoff and landing weights.