Aircraft Weight and Balance Calculator
Enter the empty weight and arm from your aircraft's weight and balance record, then the people, baggage and fuel at each station. The calculator works out total weight, moment and center of gravity for takeoff, landing and zero fuel, and plots them against the CG envelope you enter from the POH.
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Usable fuel in gallons (or liters for metric)
Shows the landing CG; volume units
How to use the Aircraft Weight and Balance Calculator
- Enter the basic empty weight and its arm from the aircraft's current weight and balance record.
- Fill in each station: front seats, rear seats, baggage and fuel, with the arms from the POH. Add extra stations if needed.
- Enter the fuel burned to see where the CG will be at landing.
- Enter the maximum weight and the envelope corners (CG, weight) from the POH chart.
- Check the result and plot: every point must be green and inside the envelope.
Weight and balance formula
- Moment = weight × arm, for every station.
- Total weight = sum of all weights. Total moment = sum of all moments.
- Center of gravity = total moment ÷ total weight.
- Fuel weight = volume × density (avgas 6.0 lb/gal, Jet A 6.7 lb/gal).
Worked example (the default example values): empty 1,680 lb × 39.0 in = 65,520; front seats 340 lb × 37 in = 12,580; baggage 20 lb × 95 in = 1,900; fuel 40 gal × 6 = 240 lb × 48 in = 11,520. Total weight 2,280 lb, total moment 91,520 lb-in, so CG = 91,520 ÷ 2,280 = 40.14 in. At 2,280 lb the example envelope allows about 36.9 in to 47.3 in, so the load is within limits.
Shifting weight to fix the CG
To move the CG by a set amount, use: weight to move = total weight × CG change ÷ distance moved. In the example, moving the CG 1 inch forward by shifting baggage from the 95 in area to a 37 in seat (58 in) needs 2,280 × 1 ÷ 58 ≈ 39 lb.
| Term | Meaning |
|---|---|
| Basic empty weight | Airframe, engine, unusable fuel, full oil and fixed equipment, from the weighing record |
| Useful load | Max weight minus basic empty weight: people, baggage and usable fuel |
| Zero fuel weight | Everything except usable fuel |
| Ramp / takeoff / landing weight | Weight before taxi, at brake release and at touchdown |
| Forward / aft CG limit | The CG range allowed at a given weight, from the envelope chart |
Tips
- Use actual weights. Ask passengers or use a scale; standard weights often underestimate people and bags.
- Check the whole flight. Takeoff, landing and zero-fuel points should all sit inside the envelope.
- Respect compartment limits. Baggage areas have their own maximum weights in the POH, even if the CG is fine.
- Combine with fuel planning. Use the aviation fuel calculator to choose a fuel load that meets your reserves without going over gross weight.
Frequently asked questions
How do you calculate weight and balance?
For each item multiply its weight by its arm (the distance from the datum) to get its moment. Add all the weights and all the moments. The center of gravity is the total moment divided by the total weight: CG = Σ(weight × arm) / Σ weight. Then check that the total weight is below the maximum and the CG is inside the approved envelope.
What is the arm and the datum?
The datum is an imaginary vertical reference plane chosen by the manufacturer, often the firewall or the wing leading edge. The arm is the horizontal distance from the datum to an item's center of gravity, in inches or millimeters. Items aft of the datum have positive arms.
What is a CG envelope?
It is the area on a weight-versus-CG chart, published in the POH, in which the airplane is approved to fly. It usually has a forward limit that moves aft as weight increases and a fixed aft limit. Enter its corner points in order and the calculator interpolates the limits at your weight.
Why does the CG move as fuel burns?
Fuel has its own arm. As you burn it, weight and moment at that arm are removed, so the CG moves toward or away from the fuel arm. Checking the landing and zero-fuel points makes sure you stay within limits for the whole flight.
What happens if the CG is out of limits?
A forward CG makes the airplane harder to rotate and flare and raises stall speed; an aft CG reduces stability and can make stall and spin recovery difficult or impossible. Move baggage or passengers, or change the fuel load, until every point is within limits. Never fly outside the approved envelope.
What is moment/1000?
Many POHs divide moments by 1,000 to keep numbers small, so a moment of 91,520 lb-in appears as 91.52. The calculator shows the full moment and the reduced moment so you can compare with the loading graph.
Can I use the preset numbers for my airplane?
No. The presets are made-up examples for practice. Every airplane has its own empty weight and CG from its weighing record, and the arms and envelope must come from that aircraft's POH or AFM.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.