Cirrus Sr20 Weight and Balance Calculator

Ensure your Cirrus SR20 is within safe operating limits.

Aircraft Configuration

Calculation Results

Formula Used:

Total Weight = Sum of all weights (Empty Weight + Pilot + Passengers + Baggage + Fuel)
Total Moment = Sum of (Weight x Arm) for each item + Empty Moment
Center of Gravity (CG) = Total Moment / Total Weight

Weight and Balance Summary

Weight Distribution

Item	Weight (lbs)	Arm (in)	Moment (in-lbs)
Empty Weight		N/A
Pilot
Front Passenger
Rear Left Passenger
Rear Right Passenger
Baggage 1
Baggage 2
Usable Fuel
Total		N/A

Weight and Balance Envelope Chart

What is Cirrus SR20 Weight and Balance?

Understanding and calculating the weight and balance for your Cirrus SR20 is a critical aspect of flight safety and performance. Weight and balance refers to the process of determining the total weight of an aircraft and the location of its center of gravity (CG) relative to a reference point called the datum. Every aircraft has specific limitations for its maximum takeoff weight and the allowable range for its CG. Operating an aircraft outside these limits can severely compromise its stability and controllability, potentially leading to a loss of control and a dangerous flight situation. The Cirrus SR20, a popular single-engine piston aircraft, requires meticulous attention to these factors due to its design and performance characteristics.

This cirrus sr20 weight and balance calculator is designed for pilots, aircraft owners, and flight instructors who need to ensure their SR20 is loaded correctly. Whether you're planning a short local flight or a longer cross-country journey, accurately accounting for passengers, baggage, and fuel is paramount. It helps answer the question: "Is my Cirrus SR20 safe to fly given its current load?"

A common misconception is that weight and balance is only a concern for large transport aircraft. In reality, it is equally, if not more, important for smaller general aviation aircraft like the SR20, as their CG envelopes are often tighter relative to their overall size and weight. Another myth is that simply staying under the maximum takeoff weight is sufficient; the location of that weight (the CG) is just as crucial, if not more so, for maintaining stability.

Cirrus SR20 Weight and Balance Formula and Mathematical Explanation

The fundamental principle behind weight and balance calculations for any aircraft, including the Cirrus SR20, involves two primary elements: total weight and the center of gravity (CG). These are determined using moments, which are the product of a weight and its distance from a reference datum.

Key Concepts:

• Datum: An imaginary vertical plane or line forward of the aircraft from which all horizontal distances are measured. For the Cirrus SR20, the datum is typically located at the aircraft's nose.
• Arm: The horizontal distance in inches from the datum to the center of gravity of an item (e.g., a passenger, baggage, fuel).
• Moment: The product of the weight of an item and its arm (Weight x Arm). This represents the turning effect of that weight about the datum. Moments are usually expressed in inch-pounds (in-lbs).
• Empty Weight & Empty Moment: The weight of the aircraft as manufactured, including unusable fuel, fixed equipment, and full operating fluids (oil). The Empty Moment is derived from this specific weight and its CG. These values are found on the aircraft's Weight and Balance sheet.
• Useful Load: The total weight of the pilot, passengers, baggage, and usable fuel.
• Maximum Takeoff Weight: The maximum allowable weight of the aircraft at the moment of liftoff.
• CG Limits: The allowable range (forward and aft) for the aircraft's center of gravity, expressed in inches from the datum.

The Calculation Steps:

1. Calculate the Moment for Each Item: For every item loaded onto the aircraft (pilot, passengers, baggage, usable fuel), multiply its weight by its respective arm.
   Moment = Weight × Arm
2. Calculate the Total Moment: Sum the moments of all individual items and add the aircraft's Empty Moment.
   Total Moment = Empty Moment + (Pilot Weight × Pilot Arm) + (Passenger Weight × Passenger Arm) + … + (Fuel Weight × Fuel Arm)
3. Calculate the Total Weight: Sum the weights of all items, including the aircraft's empty weight.
   Total Weight = Empty Weight + Pilot Weight + Passenger Weight + … + Fuel Weight
4. Calculate the Center of Gravity (CG): Divide the Total Moment by the Total Weight.
   CG = Total Moment / Total Weight
5. Verify Against Limits: Compare the calculated Total Weight against the Maximum Takeoff Weight and the calculated CG against the forward and aft CG limits specified in the Cirrus SR20 Aircraft Flight Manual (AFM) or Pilot's Operating Handbook (POH).

Variables Table:

Weight and Balance Variables

Variable	Meaning	Unit	Typical Range (Cirrus SR20)
Empty Weight	Weight of the aircraft without crew, passengers, baggage, or usable fuel.	lbs	~2,000 – 2,300
Empty Moment	Moment derived from the empty weight.	in-lbs	~70,000 – 85,000
Pilot/Passenger Weight	Weight of individuals onboard.	lbs	100 – 300 (per person)
Pilot/Passenger Arm	Horizontal distance from datum to occupant's CG.	inches	~38 (front) – 73 (rear)
Baggage Weight	Weight of items in baggage compartments.	lbs	0 – 100 (Bag 1), 0 – 50 (Bag 2)
Baggage Arm	Horizontal distance from datum to baggage CG.	inches	~90 (Bag 1) – 130 (Bag 2)
Usable Fuel Weight	Weight of fuel available for use during flight.	lbs	0 – 480 (Full tanks, ~80 US Gallons)
Fuel Tank Arm	Horizontal distance from datum to fuel tank CG.	inches	~48
Total Weight	Sum of all weights including empty weight, occupants, baggage, and fuel.	lbs	Up to ~3,061 (Max Takeoff Weight)
Total Moment	Sum of moments for all weights.	in-lbs	Varies
Center of Gravity (CG)	Location of the aircraft's balance point.	inches	~75.1 – 87.1 inches (Typical Limits for SR20; *always refer to POH*)

Note: Typical ranges are illustrative. Always consult the specific Cirrus SR20 Pilot's Operating Handbook (POH) and aircraft weight and balance documentation for exact values and limits.

Practical Examples (Real-World Use Cases)

Let's illustrate with two common scenarios for a Cirrus SR20.

Example 1: Two-Person Cross-Country Flight with Moderate Baggage

Scenario: A pilot and one passenger are flying from New York to Chicago. They have a moderate amount of baggage and nearly full fuel tanks.

Assumed Aircraft Data (Refer to POH for exact values):

• Empty Weight: 2170 lbs
• Empty Moment: 79200 in-lbs
• Max Takeoff Weight: 3061 lbs
• CG Limits: 75.1 to 87.1 inches aft of datum
• Fuel Tank Arm: 48.0 inches
• Baggage 1 Arm: 90.0 inches
• Baggage 2 Arm: 130.0 inches (not used in this example)

Inputs:

• Pilot Weight: 180 lbs, Arm: 38.0 in
• Front Passenger Weight: 160 lbs, Arm: 38.0 in
• Rear Passengers: 0 lbs
• Baggage 1 Weight: 80 lbs, Arm: 90.0 in
• Baggage 2 Weight: 0 lbs, Arm: 130.0 in
• Usable Fuel Weight: 420 lbs (approx. 70 gallons), Arm: 48.0 in

Calculator Output (Simulated):

• Total Weight: 2170 (Empty) + 180 (Pilot) + 160 (Pass) + 80 (Bag 1) + 420 (Fuel) = 3010 lbs
• Total Moment: 79200 (Empty) + (180*38) + (160*38) + (80*90) + (420*48) = 79200 + 6840 + 6080 + 7200 + 20160 = 119480 in-lbs
• Center of Gravity (CG): 119480 / 3010 = 39.7 inches from datum
• Flight Status: Well within limits!

Interpretation: The total weight (3010 lbs) is below the maximum takeoff weight (3061 lbs). However, the calculated CG (39.7 inches) is significantly forward of the typical SR20 CG limit (75.1 – 87.1 inches). This indicates the aircraft is very nose-heavy. The fuel tanks' arm (48 inches) being close to the datum, combined with the light load in the rear, contributes to this forward CG. For this flight, the pilot might consider offloading some baggage or distributing weight further aft if possible, or ensure the POH specifies such a forward limit for this configuration (though it's highly unlikely). This example highlights the importance of checking *both* weight and CG limits. *Correction*: The provided CG limit range (75.1-87.1) means the calculated 39.7 is indeed far forward. This scenario as described would typically be out of limits. A more realistic scenario for a cross-country might involve more baggage and passengers, shifting the CG aft. Let's re-evaluate with more typical conditions.

Example 1 (Revised): Two-Person Cross-Country Flight with Standard Load

Scenario: Pilot and one passenger, moderate baggage, near full fuel.

Inputs:

• Empty Weight: 2170 lbs
• Empty Moment: 79200 in-lbs
• Max Takeoff Weight: 3061 lbs
• CG Limits: 75.1 to 87.1 inches aft of datum
• Pilot Weight: 170 lbs, Arm: 38.0 in
• Front Passenger Weight: 150 lbs, Arm: 38.0 in
• Rear Left Passenger: 0 lbs
• Rear Right Passenger: 0 lbs
• Baggage 1 Weight: 100 lbs, Arm: 90.0 in
• Baggage 2 Weight: 0 lbs, Arm: 130.0 in
• Usable Fuel Weight: 450 lbs (approx. 75 gallons), Arm: 48.0 in

Calculator Output (Simulated):

• Total Weight: 2170 + 170 + 150 + 100 + 450 = 3040 lbs
• Total Moment: 79200 + (170*38) + (150*38) + (100*90) + (450*48) = 79200 + 6460 + 5700 + 9000 + 21600 = 121960 in-lbs
• Center of Gravity (CG): 121960 / 3040 = 40.1 inches from datum
• Flight Status: Out of Limits (CG too far forward)!

Interpretation: Even with a full load, the SR20's CG can be too far forward if weight isn't distributed correctly. The fuel tanks are close to the datum, and baggage is behind the passenger seats. To bring the CG into the normal range (75.1-87.1 inches), passengers would need to be in the rear seats, or a heavier load placed in Baggage Compartment 1 (or 2, if applicable). This calculation emphasizes that simply meeting the maximum weight isn't enough; CG is critical. For this flight to be legal, the pilot would need to rearrange baggage or add weight aft of the normal CG range, or reduce fuel if feasible and within range.

Example 2: Solo Flight with Maximum Baggage and Minimum Fuel

Scenario: A pilot is flying solo with maximum allowable baggage in compartment 1 and minimal fuel for a short local flight.

Inputs:

• Empty Weight: 2170 lbs
• Empty Moment: 79200 in-lbs
• Max Takeoff Weight: 3061 lbs
• CG Limits: 75.1 to 87.1 inches aft of datum
• Pilot Weight: 200 lbs, Arm: 38.0 in
• Front Passenger: 0 lbs
• Rear Passengers: 0 lbs
• Baggage 1 Weight: 100 lbs (Max), Arm: 90.0 in
• Baggage 2 Weight: 0 lbs, Arm: 130.0 in
• Usable Fuel Weight: 120 lbs (approx. 20 gallons), Arm: 48.0 in

Calculator Output (Simulated):

• Total Weight: 2170 + 200 + 100 + 120 = 2590 lbs
• Total Moment: 79200 + (200*38) + (100*90) + (120*48) = 79200 + 7600 + 9000 + 5760 = 101560 in-lbs
• Center of Gravity (CG): 101560 / 2590 = 39.2 inches from datum
• Flight Status: Out of Limits (CG too far forward)!

Interpretation: In this scenario, the total weight (2590 lbs) is well below the maximum. However, the CG (39.2 inches) is again significantly forward of the normal operating envelope. This highlights a common characteristic: with light loads and baggage in the aft compartments, the CG tends to shift forward. To make this flight safe, the pilot would need to ensure the weight distribution shifts the CG aft. This could involve placing baggage in the second compartment (if its arm is further aft) or carrying more fuel, even for a short flight. Relying solely on the maximum takeoff weight is insufficient; the calculated CG position is paramount for stable flight. Always consult the POH for the specific CG limits for your SR20 variant. This also shows the importance of having a reliable cirrus sr20 weight and balance calculator to check these figures before every flight.

How to Use This Cirrus SR20 Weight and Balance Calculator

Using this calculator is straightforward and designed to provide quick, accurate results. Follow these steps:

1. Gather Aircraft Information: Locate your Cirrus SR20's Weight and Balance sheet or Pilot's Operating Handbook (POH). You'll need the aircraft's Empty Weight and Empty Moment. These are specific to your aircraft and are determined during its initial weighing.
2. Determine Occupant and Baggage Weights: Accurately estimate or weigh the pilot, passengers, and any baggage you plan to carry. Be realistic about weights.
3. Identify Arm Stations: The "Arm" for each item (pilot, passengers, baggage, fuel) is its horizontal distance from the aircraft's datum, measured in inches. These are typically listed in the POH or Weight and Balance documentation. Common arms for the Cirrus SR20 are provided as defaults, but verify them against your specific aircraft's documentation.
4. Input Data into the Calculator:
   • Enter your aircraft's Empty Weight and Empty Moment into the respective fields.
   • Enter the weights and arms for the Pilot, Front Passenger, Rear Left Passenger, Rear Right Passenger, Baggage Compartment 1, Baggage Compartment 2, and Usable Fuel.
   • If you are flying solo, set passenger and baggage weights to 0. If you have less than full fuel, calculate the weight based on 6 lbs per US gallon and enter it.
5. Check for Errors: The calculator performs inline validation. If you see red borders or error messages, ensure all fields contain valid, non-negative numbers within reasonable ranges.
6. Calculate: Click the "Calculate" button.
7. Interpret the Results:
   • Total Weight: This is the sum of all weights entered. Compare this to your aircraft's Maximum Takeoff Weight (MTOW).
   • Total Moment: The sum of all calculated moments.
   • Center of Gravity (CG): This is the calculated balance point (Total Moment / Total Weight). Compare this to the forward and aft CG limits specified in your POH.
   • Flight Status: This provides a quick assessment of whether your aircraft is within the acceptable weight and CG envelope. "Within Limits" means it's safe to fly based on these calculations. "Out of Limits" indicates a potential problem that must be rectified before flight.
   • Weight Distribution Table: This table breaks down the contribution of each item to the total weight and moment, helping you identify which factors influence your CG the most.
   • CG Envelope Chart: This visual representation compares your calculated CG against the aircraft's operational envelope, providing an intuitive understanding of your aircraft's balance.
8. Make Decisions: If your calculated weight or CG is out of limits, you must adjust the load. This might involve removing baggage, having fewer passengers, adjusting fuel load, or repositioning items. Always recalculate after making changes.
9. Reset or Copy: Use the "Reset" button to clear the fields and start over. Use the "Copy Results" button to save the calculated values for documentation or sharing.

Remember, this calculator is a tool to aid in pre-flight planning. Always cross-reference results with your aircraft's official POH and perform thorough pre-flight checks.

Key Factors That Affect Cirrus SR20 Weight and Balance Results

Several variables significantly influence the weight and balance calculations for a Cirrus SR20. Understanding these factors is crucial for accurate pre-flight planning:

1. Empty Weight and Empty Moment Accuracy: The foundation of all calculations is the aircraft's empty weight and moment. These values can change over time due to equipment additions or removals (e.g., avionics upgrades, paint jobs, interior modifications). It's essential to have an up-to-date weighing and balance report (or a current calculation based on known changes) from the aircraft's service history. An inaccurate empty weight/moment will lead to incorrect total weight and CG calculations.
2. Pilot and Passenger Weights: People's weights vary considerably. Using a standard average might be convenient but can lead to errors. Weighing individuals or using realistic, confirmed weights is best practice. The distribution of passengers (front vs. rear seats) also has a significant impact, as rear seats have a larger arm (further from the datum), shifting the CG aft.
3. Fuel Load Management: Usable fuel is a significant weight component. The SR20 typically holds around 56 gallons usable in the main tanks, plus optional tip tanks. Fuel burns off during flight, changing the aircraft's weight and CG. For shorter flights, carrying less fuel reduces total weight but can shift the CG forward if not balanced by other loads. For longer flights, ensuring enough fuel is carried, while staying within weight limits, requires careful calculation. Remember, 1 US gallon of aviation gasoline weighs approximately 6 lbs.
4. Baggage Loading and Compartment Limits: The Cirrus SR20 has distinct baggage compartments (typically Compartment 1 and Compartment 2) with specific weight limits (e.g., 100 lbs for Bag 1, 50 lbs for Bag 2). The location (arm) of these compartments is critical. Placing heavier items in the forward compartment will shift the CG forward, while placing them in the aft compartment shifts it aft. Exceeding weight limits or placing items incorrectly can invalidate the flight.
5. Crew and Equipment Modifications: Any modifications to the aircraft, such as installing new avionics, de-icing systems, or interior furnishings, alter the empty weight and moment. These changes must be documented and incorporated into the aircraft's weight and balance records. Failure to do so can lead to cumulative errors in flight planning.
6. Definition of "Usable" vs. "Unusable" Fuel: The POH specifies usable fuel. Unusable fuel is the fuel remaining in the tanks after it can no longer be fed to the engine. Unusable fuel is typically included in the empty weight, while usable fuel is part of the useful load. Incorrectly accounting for usable fuel can lead to significant errors in total weight and CG.
7. Center Datum Reference Point: The specific arm values are relative to the aircraft's datum. While standard values exist for the SR20, different models or modifications might have slightly different datum points or arm values. Always use the figures provided in the specific aircraft's POH.

Frequently Asked Questions (FAQ)

Q1: What are the typical CG limits for a Cirrus SR20?
A1: The standard CG limits for most Cirrus SR20 models are approximately 75.1 inches to 87.1 inches aft of the datum. However, these can vary slightly between models (e.g., SR20 G1, G2, G3, G5, G6). Always refer to your specific aircraft's Pilot's Operating Handbook (POH) for exact limits.

Q2: My calculated CG is outside the limits, what should I do?
A2: If your calculated CG is too far forward, you need to shift weight aft. This could involve moving baggage to a rearward compartment, having passengers occupy rear seats, or carrying more fuel if weight allows. If your CG is too far aft, you need to shift weight forward or remove weight from the aft portion of the aircraft. Ensure your total weight is also within the Maximum Takeoff Weight (MTOW).

Q3: How often does an aircraft need to be weighed?
A3: Aircraft are typically weighed when they are new, after major modifications (like installing new avionics or a STOL kit), or if annual inspections reveal potential discrepancies. A weight and balance recalculation is required after such changes. For a well-maintained aircraft without major modifications, calculations based on documented changes are usually sufficient between weighings.

Q4: Can I carry more than the listed baggage weight if it's light items?
A4: No. The baggage compartment weight limits are based on structural limits and CG considerations. Even if the items are light, exceeding the compartment's maximum weight capacity is unsafe and illegal. Always adhere strictly to these limits.

Q5: What is the difference between "Empty Weight" and "Tare Weight"?
A5: "Tare weight" is the weight of an empty container or scale. In aviation, "Empty Weight" refers to the aircraft itself, including fixed equipment, unusable fuel, and full oil, but excluding crew, passengers, baggage, and usable fuel. Tare weight is not directly used in aircraft weight and balance calculations but is relevant in weighing procedures.

Q6: Does the weight of the pilot change the CG significantly?
A6: Yes, especially in lighter aircraft or when the aircraft is lightly loaded otherwise. A 50 lb difference in pilot weight can shift the CG by a noticeable amount, potentially moving it closer to or further from the limits. Accurate pilot and passenger weights are crucial.

Q7: How does fuel burn affect the CG during a long flight?
A7: As fuel burns off, the total weight decreases, and the CG typically shifts aft because fuel is usually located near the aircraft's center of gravity or slightly forward. This shift can be significant over long flights. Pilots must ensure the aircraft remains within CG limits throughout the entire flight, from takeoff with full fuel to landing with minimum fuel.

Q8: Is this calculator a substitute for the POH?
A8: No. This calculator is a powerful tool for pre-flight planning and quick checks. However, the official Pilot's Operating Handbook (POH) and the aircraft's specific Weight and Balance documentation are the authoritative sources for CG limits, equipment lists, and approved loading procedures. Always consult them.

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