Enter the details for each item loaded onto your SR22 to calculate the total weight, moments, and the resulting Center of Gravity (CG).
Weight of the aircraft with unusable fuel, fixed ballast, and fully equipped.
The fore/aft position of the aircraft's empty weight CG.
Weight of the pilot.
The fore/aft position of the pilot.
Weight of the passenger(s).
The fore/aft position of the passenger(s).
Current usable fuel weight (e.g., 100LL weighs ~6 lbs/gallon).
The fore/aft position of the fuel tanks.
Weight of baggage.
The fore/aft position of the baggage compartment.
Calculation Summary
—
Total Weight: —
Total Moment (lb-in): —
CG (% MAC): —
Moment = Weight × Arm (distance from datum)
Total Moment = Sum of all individual moments
Total Weight = Sum of all individual weights
CG (inches) = Total Moment / Total Weight
CG (% MAC) = ((CG (inches) – Forward Limit) / MAC) × 100
Center of Gravity Envelope
Weight and Moment Schedule
Item
Weight (lbs)
Arm (in)
Moment (lb-in)
Aircraft Empty
—
—
—
Pilot
—
—
—
Passenger
—
—
—
Fuel
—
—
—
Baggage
—
—
—
Total
—
—
—
What is SR22 Weight and Balance?
The SR22 weight and balance calculation is a critical process in aviation, specifically for the Cirrus SR22 aircraft. It involves determining the total weight of the aircraft and the location of its Center of Gravity (CG) at any given time. This calculation is paramount for ensuring flight safety. The SR22 weight and balance calculation ensures that the aircraft operates within its certified limits, providing stability and control during all phases of flight. Every pilot flying an SR22 must understand and perform these calculations accurately before each flight.
Who should use it: Any pilot operating a Cirrus SR22. This includes private pilots, commercial pilots, flight instructors, and anyone involved in the pre-flight planning for this specific aircraft. It's a fundamental skill for maintaining airworthiness and safety.
Common misconceptions: A frequent misconception is that weight and balance is a static calculation; it changes constantly with fuel burn, passenger and baggage loading/unloading. Another is that as long as the total weight is below maximum, the CG will be okay – this is incorrect. An aircraft can be overloaded by weight and still be within CG limits, or it can be within weight limits but outside CG limits, both leading to hazardous flight conditions. The SR22 weight and balance calculation is non-negotiable for safe flight.
SR22 Weight and Balance Formula and Mathematical Explanation
The core principle of weight and balance revolves around 'moments'. A moment is calculated by multiplying the weight of an object by its distance from a reference datum (a fixed point, usually the aircraft's nose or a specific station).
The formula for a moment is:
Moment = Weight × Arm
The datum is typically established by the aircraft manufacturer. For the SR22, the datum is usually located at a specific point ahead of the aircraft's nose. The 'Arm' is the horizontal distance from this datum to the center of gravity of the item being loaded (e.g., pilot, baggage, fuel). Units are typically pounds (lbs) for weight and inches (in) for the arm, resulting in a moment in pound-inches (lb-in).
To find the aircraft's overall Center of Gravity (CG), you sum all the individual moments and divide by the total weight of all items in the aircraft.
Total Moment = (Weight_item1 × Arm_item1) + (Weight_item2 × Arm_item2) + …
Total Weight = Weight_item1 + Weight_item2 + …
CG (in inches from datum) = Total Moment / Total Weight
Aircraft manufacturers provide an "Empty Weight and Balance Report" which details the aircraft's empty weight, its CG arm, and the moments of permanently installed equipment. This report is the baseline for all subsequent calculations.
The CG is often expressed as a percentage of the Mean Aerodynamic Chord (MAC). The MAC represents the average chord length of a wing. Aircraft flight manuals (AFM) specify the forward and aft CG limits in inches from the datum and also as a percentage of MAC.
The formula to convert CG in inches to % MAC is:
CG (% MAC) = ((CG_inches – Forward_CG_Limit_inches) / MAC_Length_inches) × 100
The MAC length for the SR22 is approximately 60 inches, and typical CG limits might be around 80 to 100 inches from the datum.
Variables Table
Variable
Meaning
Unit
Typical Range (SR22 context)
Weight
Mass of an item or the aircraft
lbs
0 – 3600 lbs (Max Gross Takeoff Weight)
Arm
Horizontal distance from the aircraft datum
inches (in)
~70 – 140 in (depending on item location)
Moment
Weight multiplied by Arm
lb-in
Varies widely based on weight and arm
Total Weight
Sum of all weights in the aircraft
lbs
~1800 – 3600 lbs
Total Moment
Sum of all moments of items in the aircraft
lb-in
Varies widely, e.g., ~150,000 – 350,000 lb-in
CG (inches)
Center of Gravity position from datum
inches (in)
Typically within ~80 – 100 in for SR22
MAC
Mean Aerodynamic Chord (for % MAC calculation)
inches (in)
Approx. 60 in for SR22
Forward CG Limit
The furthest forward CG position allowed
inches (in) or % MAC
Approx. 80 in or 25% MAC
Aft CG Limit
The furthest aft CG position allowed
inches (in) or % MAC
Approx. 100 in or 40% MAC
Practical Examples (Real-World Use Cases)
Example 1: Solo Cross-Country Flight
Scenario: A pilot is planning a solo cross-country flight in their SR22. They weigh 180 lbs and will be carrying 4 hours of fuel (approximately 24 gallons, weighing 144 lbs). The aircraft's empty weight and CG are known.
Result Interpretation: The calculated CG is 80.73 inches from the datum. If the SR22's forward limit is 80.0 inches and the aft limit is 100.0 inches, this loadout places the aircraft just within the forward limit (barely legal!). This highlights the sensitivity of CG with minimal load. A slightly heavier pilot or more baggage could push it out of limits.
Example 2: Two Adults and Max Baggage
Scenario: Two adults, one weighing 160 lbs and another 130 lbs, are flying with 60 lbs of baggage in the rear compartment. The aircraft has 3 hours of fuel onboard.
Result Interpretation: The calculated CG is 82.24 inches from the datum. This is well within the typical SR22 limits (80-100 inches), showing a balanced load. The aircraft has ample margin on both forward and aft CG limits.
How to Use This SR22 Weight and Balance Calculator
Using this SR22 Weight and Balance Calculator is straightforward and designed to provide quick, accurate results for your pre-flight planning.
Input Aircraft Empty Weight and Arm: Start by entering your specific SR22's empty weight and the corresponding CG arm from its Weight and Balance report. These are baseline figures.
Enter Occupant and Baggage Details: Input the weights of the pilot, passenger(s), and any baggage you plan to carry. Ensure you use accurate weights.
Specify Fuel Load: Enter the weight of the usable fuel onboard. Remember that aviation gasoline (Avgas) weighs approximately 6 lbs per gallon. Calculate your fuel weight based on the gallons required for your flight.
Input Corresponding Arms: For each item entered (pilot, passenger, baggage, fuel), input the correct CG arm. These arms are typically found in the aircraft's Pilot's Operating Handbook (POH) or Flight Manual. Our calculator uses common default arms for SR22, but always verify with your aircraft's specific documentation.
Click 'Calculate': Once all fields are populated, click the 'Calculate' button. The calculator will process the inputs and display the results.
How to Read Results:
Primary Result (CG): This shows the calculated Center of Gravity position in inches from the aircraft's datum. This is the most crucial figure.
Total Weight: The sum of all weights entered, which must not exceed the aircraft's maximum gross takeoff weight (for SR22, typically 3600 lbs).
Total Moment: The sum of all calculated moments.
CG (% MAC): If enabled and specified in your aircraft manual, this shows the CG as a percentage of the Mean Aerodynamic Chord, which is often used in official limits.
Weight and Moment Schedule Table: This table breaks down the contribution of each item to the total weight and moment, helping you identify which loading elements most affect your CG.
Chart: The chart visually represents the aircraft's CG envelope, showing the forward and aft limits and where your current loadout falls.
Decision-Making Guidance:
Compare the calculated CG (in inches and/or % MAC) against the limits specified in your SR22's official Flight Manual.
If the CG falls between the forward and aft limits, the aircraft is loaded safely regarding balance.
If the CG is forward of the forward limit, you need to shift weight aft (e.g., move passengers or baggage aft, offload non-essential items).
If the CG is aft of the aft limit, you need to shift weight forward (e.g., move passengers or baggage forward, consider lighter occupants, or carry less fuel if possible).
Ensure the Total Weight does not exceed the Maximum Gross Takeoff Weight.
Always cross-reference with your aircraft's official documentation for definitive limits and procedures. This calculator is a tool to aid in that process.
Key Factors That Affect SR22 Weight and Balance Results
Several factors significantly influence the weight and balance of an SR22, impacting flight safety and performance. Understanding these elements is crucial for every pilot.
Occupant and Baggage Distribution: The weight and location (arm) of passengers and baggage are primary contributors to CG changes. Placing heavier items further from the datum has a more significant impact on the moment and thus the CG. Proper distribution is key to staying within limits.
Fuel Load: Fuel is a major component of aircraft weight. As fuel is consumed during flight, the total weight decreases, and the CG typically shifts aft (unless fuel tanks are symmetrically located fore and aft of the CG). Managing fuel load is essential for maintaining CG within limits throughout the flight.
Aircraft Empty Weight & Equipment Changes: Any modifications, installations, or removals of equipment (e.g., avionics upgrades, new interior) will alter the aircraft's empty weight and empty weight CG. These changes necessitate an updated Weight and Balance report.
Water and Waste Systems: For aircraft equipped with flushing toilets or water systems, the weight and location of these fluids can affect CG, especially during longer flights or when tanks are partially full or empty.
Unusable Items: Items like emergency equipment, survival gear, or even personal items carried onboard contribute to the total weight. While often small, their cumulative effect and specific arms can influence the CG, particularly in lighter load conditions.
Aircraft Configuration: While less common for weight changes, certain configurations (like extending flaps or landing gear) can slightly alter the aircraft's effective CG, though this is usually accounted for within the CG envelope itself rather than the loading calculation.
Accuracy of Input Data: The calculation is only as good as the data entered. Using estimated weights, incorrect arms, or outdated empty weight figures will lead to inaccurate results, potentially compromising safety. Always use the most precise data available.
Frequently Asked Questions (FAQ)
What is the datum for the SR22?
The datum for the Cirrus SR22 is typically located at a specific point ahead of the aircraft's nose, often referenced in the aircraft's Flight Manual. For many SR22 models, it's around the firewall or leading edge of the wing, but always verify with your specific aircraft's documentation. The value for the arm is measured from this datum.
How often should I update my SR22's Weight and Balance?
You must update the Weight and Balance report and calculations whenever equipment is added, removed, or when maintenance significantly alters the aircraft's configuration. Minor day-to-day loading changes require a new calculation before each flight, but the official report only needs updates for permanent changes.
What happens if my SR22 is outside CG limits?
Operating an aircraft outside its CG limits is extremely dangerous. It can lead to reduced controllability, instability, and a higher risk of stalls or loss of control, especially during critical phases like takeoff and landing. It is illegal and unsafe.
Can I use this calculator for other aircraft?
This calculator is specifically configured with default arms and typical CG limits for the Cirrus SR22. While the principles of weight and balance are universal, the specific arms and limits vary greatly between aircraft types. For other aircraft, you must use their respective Flight Manuals and a calculator tailored to their specifications.
How does fuel burn affect CG?
As fuel is consumed, the total weight of the aircraft decreases. Typically, the CG shifts aft because fuel tanks are often located aft of the empty weight CG. This means a fully fueled aircraft might be near the forward CG limit, while a nearly empty aircraft could approach the aft CG limit.
What is the difference between Moment and CG?
Moment is a measure of the turning effect of a weight at a specific distance from a reference point (Weight x Arm). The Center of Gravity (CG) is the point where the aircraft would balance if it were a simple lever; it's calculated by dividing the Total Moment by the Total Weight. Moment is an intermediate value; CG is the final position.
What does % MAC mean in weight and balance?
% MAC stands for Percentage of the Mean Aerodynamic Chord. It's a standardized way to express the CG position relative to the wing's average chord length. Using % MAC allows for consistent CG limit definitions across different aircraft designs and makes it easier to compare limits regardless of the aircraft's specific datum and chord dimensions.
Is it safe to fly with the CG at the very limit?
Flying at the very edge of the CG limits is generally not recommended. While technically legal, it leaves very little margin for error. Unexpected factors like slight weight shifts, turbulence, or inaccuracies in calculations could push the aircraft outside safe limits. It's best practice to aim for a CG well within the established envelope.