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.
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.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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