Calcul Cg

Use this interactive center of gravity calculator to estimate total aircraft weight, total moment, loaded CG position, useful load consumed, and envelope status. Enter your aircraft loading data, then visualize the result instantly with a responsive chart.

Aircraft Center of Gravity Calculator

Designed for training and planning. Always verify with your specific aircraft POH/AFM and current weight and balance records before flight.

Expert Guide to Calcul CG: How Center of Gravity Calculations Work and Why They Matter

When pilots, mechanics, dispatchers, and aircraft owners talk about calcul CG, they are almost always referring to a center of gravity calculation. In aviation, the center of gravity is the balance point of the aircraft. It is one of the most important numbers in preflight planning because it directly influences stability, control authority, takeoff rotation, cruise efficiency, stall behavior, landing characteristics, and overall safety. A properly loaded airplane is not just under the maximum weight limit. It must also be loaded so its center of gravity remains within the approved envelope for the phase of operation.

The reason CG is so critical is simple: every pound loaded into an aircraft acts at a specific distance from a reference datum. That distance is called the arm. When you multiply a weight by its arm, you get a moment. Add up the moments from all stations and divide the total moment by the total weight, and you get the loaded center of gravity. The formula is straightforward, but the operational consequences of getting it wrong can be severe.

Core formula: CG = Total Moment / Total Weight. This calculator follows that method by summing empty weight, occupants, baggage, and fuel.

Why a correct CG calculation is more important than many pilots realize

Some pilots focus heavily on runway length, weather, and fuel reserves but treat weight and balance as a paperwork exercise. That is a mistake. An aircraft can be under gross weight and still be unsafe if the CG is too far forward or too far aft. A forward CG may increase stall speed, require higher control forces, reduce flare authority, and lengthen takeoff and landing distances. An aft CG may reduce longitudinal stability, make the aircraft feel pitch sensitive, and increase the risk of an unrecoverable stall or spin in some scenarios.

Different aircraft respond differently to the same loading shift. A two-seat trainer may tolerate minor loading changes with modest handling differences, while a high-performance single, turboprop, or business aircraft may show a much narrower balance envelope or a stronger sensitivity to baggage and fuel placement. That is why every calculation must be tied to the exact aircraft records, current equipment list, and approved flight manual data.

The key terms you must understand

• Datum: An imaginary reference point established by the manufacturer from which arms are measured.
• Arm: The horizontal distance from the datum to the item being weighed.
• Moment: Weight multiplied by arm.
• Empty Weight: The aircraft weight before payload, fuel, and passengers, based on approved records.
• Useful Load: Maximum gross weight minus empty weight.
• Payload: Occupants, baggage, and cargo that the aircraft carries.
• Ramp Weight, Takeoff Weight, Landing Weight: Operational weight states that may differ because of fuel burn or taxi fuel.
• CG Envelope: The approved range of center of gravity locations at different aircraft weights.

How this calcul CG tool performs the math

The calculator above uses a standard additive loading method. It starts with the empty weight and empty arm, then adds the weight and moment of each loading station:

1. Empty aircraft moment = empty weight × empty arm
2. Front seat moment = front occupants × front seat arm
3. Rear seat moment = rear occupants × rear seat arm
4. Baggage moment = baggage × baggage arm
5. Fuel weight = fuel quantity × fuel density
6. Fuel moment = fuel weight × fuel arm
7. Total weight = sum of all weights
8. Total moment = sum of all moments
9. Loaded CG = total moment ÷ total weight

It then compares the result against your chosen maximum gross weight and your forward and aft CG limits. In real operations, many aircraft have a curved or stepped envelope where the allowable forward limit changes as weight changes. This calculator gives a strong planning estimate, but you should still cross-check against the exact graph or table in the POH/AFM.

Real data table: common fuel densities used in aircraft loading

Fuel Type	Typical Weight per U.S. Gallon	Metric Equivalent per Liter	Why It Matters for CG
Avgas 100LL	6.0 lb/gal	1.585 kg/L	Common baseline used in many piston-aircraft weight and balance calculations.
Jet A	6.7 lb/gal	1.770 kg/L	Heavier fuel means greater total fuel moment for the same volume loaded.
Automotive gasoline	6.1 lb/gal	1.612 kg/L	Variation is modest but can still affect precise loading.

These values are common planning numbers. Operators should use manufacturer and approved operational guidance where required. The difference between 6.0 and 6.7 pounds per gallon can become substantial in aircraft carrying large fuel loads, especially if fuel is located significantly aft or forward of the datum.

Real data table: FAA standard average adult passenger weights

Category	Summer Average Weight	Winter Average Weight	Operational Relevance
Adult passenger, including carry-on	190 lb	195 lb	Useful as a standardized estimate when actual weights are not available under approved procedures.
Adult male, including carry-on	200 lb	205 lb	Illustrates why underestimating body weight skews loading calculations.
Adult female, including carry-on	179 lb	184 lb	Supports more realistic planning than outdated assumptions from older manuals.

These standardized values, published through FAA guidance, show why pilots should not rely on old habits or unrealistic assumptions. In many small aircraft, replacing a 170-pound estimate with a 200-pound actual occupant can move the loaded CG enough to matter, especially when multiple seats are occupied and baggage is added behind the rear seats.

Forward CG vs aft CG: what changes in aircraft handling

A forward CG generally makes the airplane more stable in pitch but less agile. You may need more back pressure to rotate on takeoff and more elevator authority to flare at touchdown. This can be particularly noticeable in short-field operations or when landing at higher weights. Nosewheel loading can also increase, which affects braking and runway wear characteristics.

An aft CG, by contrast, often reduces the force required to pitch the nose and may improve cruise efficiency slightly because of lower tail download. However, the tradeoff can be dangerous. The airplane may become less stable, recover more slowly from disturbances, and be easier to overcontrol. Stall recovery can be more difficult because the stabilizer or elevator has less leverage margin to lower the nose. This is one reason why aft-CG loading has been implicated in serious accidents.

Common loading mistakes pilots make

• Using old empty-weight figures after avionics, interiors, or equipment changes.
• Forgetting that full fuel can push an aircraft over gross weight before passengers are added.
• Ignoring baggage area limits and focusing only on total gross weight.
• Using a single generic forward or aft limit when the actual envelope varies by weight.
• Assuming all fuel tanks affect CG equally without checking station data.
• Failing to consider CG movement after fuel burn.
• Estimating passenger weights too optimistically.

Why fuel burn changes the answer

One of the most overlooked points in calcul CG planning is that the center of gravity can move during the flight. If the fuel tanks are aft of the empty CG, burning fuel may shift the center of gravity forward. If the tanks are forward of the loaded CG, fuel burn may shift it aft. In some aircraft this movement is small; in others it is operationally important. That is why transport-category procedures and many sophisticated general aviation loading sheets evaluate not just ramp weight but takeoff, zero-fuel, and landing conditions.

For training aircraft, fuel is often near the cabin area and the CG shift may remain manageable, but it should never be assumed. In utility aircraft, cargo aircraft, or planes with significant baggage compartments, the movement can be much more pronounced. A good loading plan should answer at least two questions: is the aircraft within limits for takeoff, and will it still be within limits after the expected fuel burn?

How to use this calculator more accurately

1. Open the aircraft’s current weight and balance record.
2. Enter the exact basic empty weight and empty arm from the approved documents.
3. Use the real station arms from your POH, AFM, or equipment supplement.
4. Enter actual occupant and baggage weights whenever possible.
5. Select the correct fuel type and quantity.
6. Compare the result to your actual CG envelope, not just a simple min and max number.
7. Recheck after changing passengers, bags, fuel level, or installed equipment.

Regulatory and training perspective

Weight and balance is not just best practice. It is fundamental to airworthiness and legal operation. The FAA emphasizes compliance with approved loading limitations because the airplane was tested and certified only within those boundaries. Exceeding them can invalidate performance expectations and compromise structural, aerodynamic, and controllability margins. If you are a student pilot, expect your instructor or examiner to treat CG calculations as part of normal decision-making, not a rote math exercise.

For operators in the United States, several high-value reference sources are available online. The FAA Airplane Flying Handbook explains the operational effects of loading and handling. The FAA weight and balance advisory guidance covers practical methods and standard assumptions. For an academic treatment of stability and balance concepts, engineering materials from institutions such as MIT provide deeper theory on how the center of gravity affects longitudinal stability.

Interpreting the chart below the calculator

The chart generated by this tool helps you see two things at once. First, it plots the moment contribution of each station, making it easier to identify which loading area is driving the final result. Second, it marks the final loaded CG against your entered forward and aft limits. If the final point sits outside the approved range, you should remove weight, shift payload, or alter fuel planning until the aircraft returns to a safe loading state.

Practical examples of corrective action

If the aircraft is overweight, the only real solution is to reduce fuel, payload, or cargo. If the aircraft is too far forward, you may need to move baggage aft, reduce forward-seat load, or adjust fuel if the fuel station helps shift the balance. If the aircraft is too far aft, move baggage forward, reduce rear-seat load, or alter the fuel plan if the tanks are positioned beneficially. Every corrective change should be recalculated because one adjustment can affect both total weight and CG.

Final takeaway

A proper calcul CG process is one of the clearest examples of disciplined aeronautical decision-making. It translates real-world loading choices into a measurable safety margin. The mathematics are simple, but the consequences are profound. When done correctly, a center of gravity calculation tells you whether the airplane will rotate, climb, cruise, stall, descend, and land within the performance and handling expectations that its designers intended. Use tools like this calculator to speed up the arithmetic, but anchor every final decision to your official aircraft data and the exact operating limitations that apply to your flight.

Educational use only. Always defer to the approved Aircraft Flight Manual, Pilot’s Operating Handbook, type certificate data, and current weight and balance records for operational decisions.