Aircraft Weight and Balance Calculator
Calculate aircraft center of gravity (CG) from weights and arms.
Verify CG is within limits before flight.
Essential pre-flight check.
Center of Gravity
How Aircraft Weight and Balance Is Calculated
Weight and balance ensures an aircraft’s center of gravity (CG) falls within the approved envelope. An out-of-limit CG makes an aircraft difficult or impossible to control.
Moment Formula:
Moment = Weight × Arm
CG = Total Moment / Total Weight
Where:
- Weight = mass of item in lbs or kg
- Arm = distance from reference datum in inches or meters
- Moment = weight × arm (in-lbs or kg-m)
- CG = center of gravity location (same unit as arm)
Worked Example (Cessna 172 typical values):
| Item | Weight (lbs) | Arm (in) | Moment (in-lbs) |
|---|---|---|---|
| Empty aircraft | 1,669 | 41.1 | 68,596 |
| Front seats (2×180 lbs) | 360 | 37.0 | 13,320 |
| Rear seats (0) | 0 | 73.0 | 0 |
| Fuel (40 gal, 6 lb/gal) | 240 | 48.0 | 11,520 |
| Baggage (30 lbs) | 30 | 95.0 | 2,850 |
| Totals | 2,299 | 96,286 |
- CG = 96,286 / 2,299 = 41.88 inches
- Check against CG envelope: must be between ~35.0 and 47.3 inches at 2,299 lbs → Within limits ✓
Max Gross Weight: Cessna 172S = 2,550 lbs. Never exceed this, even if CG is in range.
Aft CG danger: Elevator authority insufficient; aircraft can enter unrecoverable pitch-up. Forward CG: excessive nose-down tendency, higher stall speed, more drag.