Enter each item's weight and arm (or moment). Get gross weight, total moment, and CG, checked against your limits, with a weight-shift solver for fixing an out-of-envelope load.
Enter weight plus either arm or moment; the third value fills in. Fuel: avgas 6.0 lb/gal, jet fuel 6.84, oil 7.5.
Limits (from your POH, optional)Moment = weight × arm. CG = total moment ÷ total weight. That is the entire method: every item in the airplane multiplied by its distance from the datum, summed, and divided. What matters is what you do with the answer: check it against the envelope at takeoff and at landing fuel, and move weight, not hope, when it falls outside. Arms and limits come from your aircraft's papers. Entries stay on this device.
Everything hangs on a lever. The datum is an imaginary reference plane (often the firewall or the tip of the spinner; your POH says where); each item's arm is its distance aft of that plane. Weight × arm = moment, the twisting force the item applies. Sum the weights, sum the moments, divide: CG = Σ moment ÷ Σ weight. The POH publishes an envelope of acceptable CG positions per weight; inside it the airplane was certified to be controllable and recoverable, outside it nobody has promised you anything.
Some POHs use a reduction factor (moments divided by 100 or 1,000 to keep the numbers small); enter moments here at face value, or stay consistent and read the total the same way.
Load it with the button above:
| Item | Weight (lb) | Arm (in) | Moment (lb-in) |
|---|---|---|---|
| Empty aircraft | 1,495 | 101.4 (computed) | 151,593 (given) |
| Front seats | 380 | 64 | 24,320 |
| Rear seat | 150 | 75 | 11,250 |
| Fuel (30 gal) | 180 | 96 | 17,280 |
Totals: 2,205 lb, 204,443 lb-in, CG 92.72 in. Now the what-if from the same manual page: the rear passenger gets out and 50 lb of fuel goes in → 2,105 lb, CG 94.06 in. Two edits, four seconds, new answer.
When the CG lands outside the envelope, the fix is moving something. The formula: weight to move = total weight × required CG change ÷ distance the weight moves.
e.g., baggage compartment A to compartment B
Example: at 7,500 lb total, moving the CG 1 inch by relocating cargo 120 inches means moving 7,500 × 1 ÷ 120 = 62.5 lb.
Common QuestionsFor private GA flying, use real weights: ask, and add winter clothing. Standard-average weights belong to air-carrier programs with big cabins where errors average out. In a four-seat airplane one optimistic guess is 5% of gross weight.
Still no. Max gross weight is a structural and performance limitation: takeoff distance, climb rate, and stall speed were all certified at or below it. The usual fix is fuel: fly with partial tanks and add a stop. The fuel calculator tells you what the shorter fuel load does to endurance.
Usually a stale empty weight. Every equipment change (new avionics, repainting) updates the empty weight and moment in the aircraft records; a spreadsheet built years ago drifts from the papers. The current weight-and-balance report in the aircraft binder wins over any tool, including this one.
Fuel weight is the load you can actually negotiate; see what partial tanks cost in endurance.
The other half of the preflight math: headings, times, and fuel per leg.
Heavy and hot compound each other; check both before a full-load summer takeoff.
FlightDecide carries your aircraft's real station arms and limits in its profile and checks every flight's loading automatically, alongside weather, NOTAMs, fuel, and performance.
Get FlightDecide on the App StoreEducational tool for flight-planning practice. It is advisory only and not a substitute for your POH, your aircraft's current weight-and-balance report, or your own judgment as pilot in command (14 CFR 91.3). Sources: FAA Weight-Shift and Balance Handbook (FAA-H-8083-1B); Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Ch. 10. Last reviewed: July 17, 2026.