Aircraft Weight & Balance Calculator

Ensure your flight is safe and legal by accurately calculating your aircraft's weight and balance. This tool helps determine the Center of Gravity (CG) and total weight.

Weight & Balance Calculation

Weight & Balance Data Table

Aircraft Loading Details

Item	Weight (lbs/kg)	Arm (inches from datum)	Moment (lb-in / kg-m)
Empty Weight
Fuel
Front Seat(s)
Rear Seat(s)
Baggage
TOTALS

Center of Gravity (CG) Envelope Chart

Visual representation of your aircraft's CG relative to its operational limits.

What is Aircraft Weight & Balance?

Aircraft weight and balance is a critical aspect of aviation safety and operational efficiency. It involves calculating the total weight of an aircraft and determining the location of its Center of Gravity (CG). The CG is the point where the aircraft would balance if suspended. Maintaining the CG within specified limits, known as the CG envelope, is paramount for stable and controllable flight. An improperly loaded aircraft can be unstable, difficult to control, and may even lead to a loss of control or structural failure. This calculation is not just a regulatory requirement; it's a fundamental safety procedure for every pilot and operator. Understanding and correctly applying weight and balance principles ensures that the aircraft performs as designed and remains safe throughout all phases of flight, from takeoff to landing. This is why a reliable aircraft weight & balance calculator is an indispensable tool for pilots.

Who Should Use It?

Anyone involved in the operation or planning of an aircraft should use a weight and balance calculation. This includes:

• Pilots: For pre-flight planning and ensuring safe loading.
• Flight Dispatchers: For commercial operations, ensuring compliance and safety.
• Aircraft Owners: To understand the operational capabilities and limitations of their aircraft.
• Maintenance Personnel: When performing modifications or inspections that might affect weight or balance.
• Aviation Students: To learn and practice essential flight planning skills.

Common Misconceptions

Several common misconceptions exist regarding aircraft weight and balance:

• "It's just about not exceeding max weight." While maximum weight is crucial, the CG location is equally, if not more, important for stability and control.
• "My aircraft feels fine, so balance must be okay." An aircraft can be aerodynamically stable even if its CG is outside the limits, but control effectiveness will be severely compromised, making it dangerous.
• "The POH (Pilot's Operating Handbook) numbers are always exact." The POH provides certified limits and typical values. Actual weights and CGs of occupants, baggage, and fuel can vary, requiring precise calculation for each flight.
• "Weight and balance is only for small planes." Larger, commercial aircraft have even more stringent and complex weight and balance requirements due to their size, complexity, and passenger loads.

Aircraft Weight & Balance Formula and Mathematical Explanation

The core principle behind aircraft weight and balance calculations is the concept of moments. A moment is the product of a weight and its distance from a reference point (the datum). By calculating the total moment and total weight, we can determine the aircraft's Center of Gravity (CG).

Step-by-Step Derivation

1. Calculate Individual Moments: For each item loaded onto the aircraft (empty weight, fuel, occupants, baggage), calculate its moment by multiplying its weight by its distance from the datum (its arm).
   Moment = Weight × Arm
2. Sum All Moments: Add up the moments of all items to find the total moment of the aircraft.
   Total Moment = Σ (Weight × Arm)
3. Sum All Weights: Add up the weights of all items to find the total weight of the aircraft.
   Total Weight = Σ Weight
4. Calculate the Center of Gravity (CG): Divide the total moment by the total weight to find the CG location.
   CG = Total Moment / Total Weight

Variable Explanations

Understanding the variables used in these calculations is key:

Variable	Meaning	Unit	Typical Range
Wempty	Aircraft Empty Weight	lbs or kg	Varies greatly by aircraft type (e.g., 1000 – 50000+ lbs)
CGempty	Empty Weight Center of Gravity	Inches from datum	Specific to aircraft type (e.g., 90 – 110 inches)
Wfuel	Fuel Weight	lbs or kg	0 to max fuel capacity (e.g., 0 – 500 lbs)
CGfuel	Fuel Center of Gravity	Inches from datum	Specific to tank location (e.g., 95 – 105 inches)
Woccupants	Occupants' Weight (Pilot, Passengers)	lbs or kg	e.g., 150 – 250 lbs per person
CGoccupants	Occupants' Center of Gravity	Inches from datum	Location of seats (e.g., 96 – 115 inches)
Wbaggage	Baggage Weight	lbs or kg	0 to max baggage capacity (e.g., 0 – 100 lbs)
CGbaggage	Baggage Compartment CG	Inches from datum	Location of baggage area (e.g., 110 – 130 inches)
Mtotal	Total Moment	lb-in or kg-m	Calculated value (e.g., 150,000 – 500,000+ lb-in)
Wtotal	Total Weight	lbs or kg	Sum of all weights (e.g., 1500 – 3000 lbs)
CGcurrent	Current Center of Gravity	Inches from datum	Calculated value (e.g., 92 – 103 inches)
CGmin	Minimum Allowable CG	Inches from datum	Aircraft limit (e.g., 90 inches)
CGmax	Maximum Allowable CG	Inches from datum	Aircraft limit (e.g., 105 inches)
Wmax	Maximum Allowable Takeoff Weight	lbs or kg	Aircraft limit (e.g., 2500 lbs)

Practical Examples (Real-World Use Cases)

Let's illustrate with two common scenarios using a hypothetical light aircraft with a datum at the firewall, a max takeoff weight of 2500 lbs, and CG limits of 90.0 to 105.0 inches.

Example 1: Solo Flight with Full Fuel

A pilot is flying solo and wants to take off with maximum fuel.

• Aircraft Empty Weight: 1500 lbs
• Empty Weight CG: 95.5 inches
• Fuel Weight (Full Tanks): 400 lbs
• Fuel CG: 98.0 inches
• Pilot Weight: 180 lbs
• Pilot CG: 96.0 inches
• Baggage Weight: 0 lbs
• Baggage CG: 125.0 inches (typical aft location)
• Max Allowable Takeoff Weight: 2500 lbs
• CG Limits: 90.0 – 105.0 inches

Calculations:

• Empty Weight Moment: 1500 lbs * 95.5 in = 143,250 lb-in
• Fuel Weight Moment: 400 lbs * 98.0 in = 39,200 lb-in
• Pilot Weight Moment: 180 lbs * 96.0 in = 17,280 lb-in
• Baggage Weight Moment: 0 lbs * 125.0 in = 0 lb-in
• Total Moment: 143,250 + 39,200 + 17,280 + 0 = 199,730 lb-in
• Total Weight: 1500 + 400 + 180 + 0 = 2080 lbs
• Current CG: 199,730 lb-in / 2080 lbs = 96.02 inches

Interpretation: The total weight (2080 lbs) is below the max allowable takeoff weight (2500 lbs). The current CG (96.02 inches) is within the allowable limits (90.0 – 105.0 inches). This configuration is safe for takeoff.

Example 2: Two Adults, Baggage, and Reduced Fuel

Two adults are flying with baggage, but they are only taking 2 hours of fuel.

• Aircraft Empty Weight: 1500 lbs
• Empty Weight CG: 95.5 inches
• Fuel Weight (2 hours): 200 lbs
• Fuel CG: 98.0 inches
• Front Seat Occupants Weight: 180 lbs + 160 lbs = 340 lbs
• Front Seat CG: 96.0 inches
• Rear Seat Occupants Weight: 0 lbs
• Rear Seat CG: 110.0 inches
• Baggage Weight: 50 lbs
• Baggage CG: 125.0 inches
• Max Allowable Takeoff Weight: 2500 lbs
• CG Limits: 90.0 – 105.0 inches

Calculations:

• Empty Weight Moment: 1500 lbs * 95.5 in = 143,250 lb-in
• Fuel Weight Moment: 200 lbs * 98.0 in = 19,600 lb-in
• Front Seat Moment: 340 lbs * 96.0 in = 32,640 lb-in
• Rear Seat Moment: 0 lbs * 110.0 in = 0 lb-in
• Baggage Moment: 50 lbs * 125.0 in = 6,250 lb-in
• Total Moment: 143,250 + 19,600 + 32,640 + 0 + 6,250 = 201,740 lb-in
• Total Weight: 1500 + 200 + 340 + 0 + 50 = 2090 lbs
• Current CG: 201,740 lb-in / 2090 lbs = 96.53 inches

Interpretation: The total weight (2090 lbs) is well below the maximum (2500 lbs). The current CG (96.53 inches) is within the allowable limits (90.0 – 105.0 inches). This flight is also safe.

How to Use This Aircraft Weight & Balance Calculator

Using this aircraft weight & balance calculator is straightforward. Follow these steps for accurate flight planning:

1. Gather Aircraft Data: Locate your aircraft's Pilot's Operating Handbook (POH) or Weight & Balance manual. You'll need the aircraft's empty weight, empty weight CG, maximum allowable takeoff weight, and the forward and aft CG limits.
2. Determine Loading: Estimate or confirm the weight and intended location (arm) for all items you plan to carry:
   • Fuel: Calculate the weight based on the type of fuel and the number of gallons/liters you'll carry. Note the CG for the fuel tanks.
   • Occupants: Use actual weights for the pilot and passengers. Note the CG location for each seating position.
   • Baggage: Weigh your baggage and note the CG of the baggage compartment.
3. Input Data into Calculator: Enter the values into the corresponding fields in the calculator above. Ensure you use consistent units (e.g., all lbs or all kg, all inches from datum).
4. Calculate: Click the "Calculate" button.
5. Review Results: The calculator will display:
   • Total Weight: The sum of all weights entered.
   • Total Moment: The sum of all calculated moments.
   • Current CG: The calculated Center of Gravity.
   • Weight Status: Indicates if the total weight is within limits.
   • CG Status: Indicates if the current CG is within the forward and aft limits.
6. Interpret Findings: If both weight and CG are within limits, your aircraft is loaded safely. If either is outside the limits, you must adjust the loading (e.g., remove baggage, redistribute weight, carry less fuel) and recalculate until all parameters are within the safe envelope.
7. Reset: Use the "Reset" button to clear the form for a new calculation.
8. Copy Results: Use the "Copy Results" button to save or share your calculated data.

Key Factors That Affect Aircraft Weight & Balance Results

Several factors significantly influence the weight and balance calculations for any flight. Understanding these is crucial for accurate planning:

1. Aircraft Empty Weight & CG: This is the baseline. Any changes to the aircraft (e.g., modifications, repairs, equipment additions/removals) will alter the empty weight and its CG. Accurate records are vital.
2. Fuel Load: Fuel is often the most variable item. Its weight changes constantly during flight as it's consumed. The location of the fuel tanks (and thus the fuel's CG) also plays a significant role. Carrying less fuel shifts the CG forward, while carrying more shifts it aft.
3. Occupant and Baggage Weight: Passenger and cargo weights can vary significantly. Overestimating or underestimating these can lead to incorrect calculations. Distributing weight unevenly within compartments can also affect the effective CG.
4. Datum Location: The choice of datum (reference point) is arbitrary but must be consistent. A datum located far forward will result in larger moment values, while a datum located aft will result in smaller values. The CG limits are always specified relative to the aircraft's datum.
5. Arm Lengths: The distance of each item's weight from the datum (the arm) is critical. Even small errors in measuring or estimating arm lengths can lead to significant CG calculation errors, especially for items located far from the datum.
6. CG Envelope Limits: These are defined by the aircraft manufacturer and certified by aviation authorities. They represent the range of CG positions where the aircraft is aerodynamically stable and controllable. Exceeding these limits compromises safety.
7. Takeoff vs. Landing Weight: While this calculator focuses on takeoff weight, pilots must also consider landing weight. As fuel is burned, the total weight decreases, and the CG typically shifts forward. Ensuring the CG remains within limits throughout the flight, including at landing, is essential.

Frequently Asked Questions (FAQ)

Q1: What is the datum in weight and balance calculations?
A: The datum is an imaginary vertical line or plane established by the manufacturer from which all horizontal distances (arms) are measured. It's the zero reference point for calculating moments and CG.

Q2: How do I find the CG of my passengers or baggage?
A: The POH or Weight & Balance manual will specify the CG location (arm) for each seat and the baggage compartment(s). If loading baggage in a specific spot, you might need to calculate its CG based on its position within the compartment.

Q3: What happens if my CG is outside the limits?
A: Flying an aircraft with its CG outside the allowable limits is dangerous and illegal. It can lead to reduced control effectiveness, instability, and potentially a loss of control. You must adjust the load to bring the CG back within limits before flight.

Q4: Does the weight of the pilot matter?
A: Absolutely. The pilot's weight is a significant factor in the total weight and the overall CG. It must be accurately accounted for in every calculation.

Q5: Can I use this calculator for any aircraft?
A: This calculator provides the framework. However, you MUST use the specific weight, CG, and limit data for YOUR aircraft model, as found in its official POH or Weight & Balance manual. Using generic data is unsafe.

Q6: What is "moment"?
A: Moment is a measure of the turning effect of a weight at a distance from the datum. It's calculated as Weight × Arm. Summing moments helps determine the overall balance point (CG).

Q7: How often should I check weight and balance?
A: You should perform a weight and balance calculation for every flight, especially if the loading conditions change (different passengers, baggage, or fuel load). For aircraft with significant modifications, a new weight and balance computation might be required.

Q8: What if my aircraft has multiple fuel tanks?
A: If fuel is transferred between tanks during flight, the CG will change. You need to calculate the CG for the specific fuel configuration you intend to use for takeoff and consider how it might change during the flight. The POH will detail this.