Aircraft Weight and Balance Calculator Online

Calculate Your Aircraft's Weight and Balance

Ensure your aircraft operates safely within its designed limits. Proper weight and balance management is critical for flight stability, performance, and regulatory compliance. Use this calculator to determine your aircraft's current center of gravity (CG) and verify it falls within the allowable range.

Weight and Balance Summary

Item	Weight (lbs)	Arm (inches)	Moment (in-lbs)
Aircraft Empty Weight (AEW)	—	—	—
Usable Fuel	—	—	—
Payload (Passengers/Baggage/Cargo)	—	—	—
Total Aircraft Weight	—	—	—
Calculated Center of Gravity (CG)	—	—	—
Allowable CG Range	—	—	—

What is Aircraft Weight and Balance?

Aircraft weight and balance refers to the process of determining the empty weight and center of gravity (CG) of an aircraft and then calculating the CG for a specific loading condition. This is a fundamental aspect of aviation safety, ensuring that the aircraft remains stable and controllable throughout its flight envelope. The CG is the point where the aircraft would balance if suspended. Its position relative to the aircraft's structure is critical for aerodynamic stability and performance.

Who should use it: Pilots, aircraft owners, maintenance personnel, and flight operations managers all rely on accurate weight and balance calculations. Pilots must verify that their aircraft is loaded within limits before every flight. Owners and maintenance crews need to maintain up-to-date weight and balance records. Flight operations managers use these calculations for scheduling and payload optimization.

Common misconceptions: A frequent misconception is that as long as the total weight is within the maximum takeoff weight (MTOW), the aircraft is safe. However, the CG position is equally, if not more, important. An aircraft can be within its weight limit but still be dangerously out of balance, leading to instability or loss of control. Another misconception is that weight and balance is a static calculation; it's dynamic and changes with fuel burn, passenger movement, and cargo shifts.

Aircraft Weight and Balance Formula and Mathematical Explanation

The core of aircraft weight and balance calculation involves understanding moments and the center of gravity. A moment is the product of a weight and its distance from a reference point called the datum. The datum is an arbitrary vertical plane or point from which all horizontal distances (arms) are measured.

Key Formulas:

1. Moment Calculation: For each item loaded onto the aircraft (empty weight, fuel, passengers, baggage), its moment is calculated by multiplying its weight by its arm (distance from the datum).
   Moment = Weight × Arm
2. Total Moment Calculation: The sum of all individual moments gives the total moment for the aircraft in its current configuration.
   Total Moment = Σ (Weightᵢ × Armᵢ)
3. Total Weight Calculation: The sum of all weights gives the total weight of the aircraft.
   Total Weight = Σ Weightᵢ
4. Center of Gravity (CG) Calculation: The CG is found by dividing the total moment by the total weight.
   CG = Total Moment / Total Weight

Variable Explanations:

Weight and Balance Variables

Variable	Meaning	Unit	Typical Range
Weight (W)	The mass of an item or the entire aircraft.	Pounds (lbs) or Kilograms (kg)	0 to Max Takeoff Weight (MTOW)
Arm (A)	Horizontal distance from the datum to the center of gravity of an item or the aircraft.	Inches (in) or Meters (m)	Varies greatly by aircraft type and datum location. Can be positive or negative.
Moment (M)	The product of weight and arm; represents the turning effect of the weight.	Pound-Inches (lb-in) or Kilogram-Meters (kg-m)	Varies greatly. Often large numbers.
Datum	An arbitrary reference point or plane from which all arms are measured.	N/A	Defined in the aircraft's Type Certificate Data Sheet (TCDS) or Pilot's Operating Handbook (POH).
Empty Weight (EW)	Weight of the aircraft with fixed equipment, unusable fuel, and no payload.	lbs or kg	Specific to aircraft model.
Empty Weight CG (EWCG)	CG of the aircraft at its empty weight.	Inches or % MAC	Specific to aircraft model.
Payload	Weight of passengers, baggage, and cargo.	lbs or kg	0 to Max Payload.
Usable Fuel	Fuel available for use during flight.	lbs or kg	0 to Max Usable Fuel.
Center of Gravity (CG)	The point where the aircraft would balance.	Inches or % MAC (Mean Aerodynamic Chord)	Must be within the specified allowable range for safe flight.
Allowable CG Range	The limits within which the CG must be for safe operation (takeoff, cruise, landing).	Inches or % MAC	Defined in the aircraft's POH.

Practical Examples (Real-World Use Cases)

Understanding weight and balance is crucial for various flight scenarios. Here are two practical examples:

Example 1: Standard Cross-Country Flight

A pilot is preparing for a 2-hour cross-country flight in a Cessna 172. The aircraft's POH specifies an Empty Weight of 1500 lbs with an EWCG of 95.5 inches from the datum. The allowable CG range for takeoff is 90.0 to 105.0 inches.

• Usable Fuel: 48 gallons × 6 lbs/gallon = 288 lbs. The fuel tanks are located at an arm of 98.0 inches.
• Payload: Pilot (180 lbs) and one passenger (160 lbs) = 340 lbs. The pilot's seat is at 96.0 inches, and the passenger's seat is at 102.0 inches. For simplicity, we'll average the payload arm or use the CG of the combined payload. Let's assume the combined payload CG is 99.0 inches.

Calculations:

• AEW Moment: 1500 lbs × 95.5 in = 143,250 lb-in
• Fuel Moment: 288 lbs × 98.0 in = 28,224 lb-in
• Payload Moment: 340 lbs × 99.0 in = 33,660 lb-in
• Total Moment: 143,250 + 28,224 + 33,660 = 205,134 lb-in
• Total Weight: 1500 lbs + 288 lbs + 340 lbs = 2128 lbs
• Current CG: 205,134 lb-in / 2128 lbs = 96.39 inches

Interpretation: The calculated CG of 96.39 inches falls within the allowable takeoff range of 90.0 to 105.0 inches. The aircraft is loaded safely for takeoff.

Example 2: Cargo Operation with Maximum Payload

A pilot is operating a light twin-engine aircraft for a cargo mission. The aircraft's POH indicates an Empty Weight of 4000 lbs with an EWCG of 150 inches. The allowable CG range for landing is 145.0 to 165.0 inches. The aircraft has a maximum payload capacity of 1200 lbs.

• Usable Fuel: 100 gallons × 7 lbs/gallon = 700 lbs. Fuel tanks are at an arm of 155 inches.
• Payload: Maximum payload of 1200 lbs. Let's assume the cargo is loaded such that its CG is at 160 inches.

Calculations:

• AEW Moment: 4000 lbs × 150 in = 600,000 lb-in
• Fuel Moment: 700 lbs × 155 in = 108,500 lb-in
• Payload Moment: 1200 lbs × 160 in = 192,000 lb-in
• Total Moment: 600,000 + 108,500 + 192,000 = 900,500 lb-in
• Total Weight: 4000 lbs + 700 lbs + 1200 lbs = 5900 lbs
• Current CG: 900,500 lb-in / 5900 lbs = 152.63 inches

Interpretation: The calculated CG of 152.63 inches is within the allowable landing range of 145.0 to 165.0 inches. The aircraft is loaded safely for landing, even with maximum payload and a significant amount of fuel.

How to Use This Aircraft Weight and Balance Calculator

Using this online aircraft weight and balance calculator is straightforward. Follow these steps to ensure your flight's safety:

1. Gather Aircraft Data: Obtain your aircraft's Empty Weight (AEW) and Empty Weight Center of Gravity (EWCG) from its Weight and Balance manual or Pilot's Operating Handbook (POH). Note the datum used.
2. Determine Payload Details: Calculate the total weight of your passengers, baggage, and cargo. Find the center of gravity (arm) for each item or the combined payload, as specified in your aircraft's manual.
3. Calculate Fuel Load: Determine the amount of usable fuel you will carry, converting gallons to pounds (typically 6 lbs/gallon for avgas, 7 lbs/gallon for jet fuel). Find the arm for your fuel tanks.
4. Input Values: Enter the AEW, EWCG, Usable Fuel Weight, Fuel CG, Payload Weight, and Payload CG into the respective fields of the calculator.
5. Calculate: Click the "Calculate" button.

How to Read Results:

• Total Weight: This is the sum of all weights entered. Ensure it does not exceed the Maximum Takeoff Weight (MTOW) or Maximum Landing Weight (MLW) specified in your POH.
• Current CG: This is the calculated center of gravity for your loaded aircraft.
• Allowable CG Range: This displays the CG limits for the current phase of flight (e.g., takeoff, landing) as defined in your POH.
• Interpretation: Compare your "Current CG" to the "Allowable CG Range". If your Current CG falls within the range, your aircraft is balanced correctly. If it falls outside the range, you must adjust the loading (e.g., move baggage, reduce fuel, change passenger positions) and recalculate until it is within limits.

Decision-Making Guidance: Always prioritize safety. If your calculated CG is outside the allowable range, do not fly. Consult your aircraft's POH and consider seeking assistance from a qualified aviation professional. This calculator is a tool to aid in the process, but the ultimate responsibility lies with the pilot to ensure safe loading.

Key Factors That Affect Aircraft Weight and Balance Results

Several factors significantly influence an aircraft's weight and balance calculations, impacting flight safety and performance:

1. Fuel Load: The amount of fuel carried is a major variable. As fuel is consumed during flight, the aircraft's total weight decreases, and its CG typically shifts forward (if fuel tanks are forward of the CG) or aft (if fuel tanks are aft of the CG). This dynamic change requires pilots to monitor CG throughout the flight.
2. Payload Distribution: The weight and placement of passengers, baggage, and cargo are critical. Placing heavy items far aft can quickly move the CG beyond the allowable limit, while placing them far forward can result in an excessively nose-heavy condition. Careful loading is essential.
3. Aircraft Configuration Changes: Modifications, repairs, or additions to the aircraft (e.g., installing new avionics, painting, adding long-range tanks) alter the empty weight and EWCG. These changes must be accurately documented and incorporated into the aircraft's official weight and balance records.
4. Datum Location: The choice of datum significantly affects the magnitude of the moments and CG values. While the datum is fixed for a specific aircraft type, understanding its location (e.g., nose of the aircraft, firewall) is crucial for correct calculations. A datum far forward will result in larger positive moments and CG values.
5. Usable vs. Unusable Fuel: Only usable fuel contributes to the aircraft's weight and moment during flight. Unusable fuel (fuel remaining in the tanks after the engine can no longer run) is part of the empty weight and its CG is factored into the EWCG.
6. Crew Weight and Equipment: The weight of the pilot(s) and any flight crew, along with their equipment, must be accounted for. This is often included in the payload calculation but should be considered specifically, especially in smaller aircraft where crew weight is a significant percentage of total weight.
7. Water/Waste Systems: For aircraft equipped with lavatories, the weight and location of water tanks (fresh and waste) can impact the CG. These must be accounted for, especially during loading and unloading operations.
8. Dynamic Loading: While calculations are typically static, real-world loading can involve dynamic shifts. Passengers moving around, baggage settling, or cargo shifting can temporarily alter the CG. Pilots must be aware of these possibilities.

Frequently Asked Questions (FAQ)

Q1: What is the difference between Maximum Takeoff Weight (MTOW) and Maximum Landing Weight (MLW)?

MTOW is the maximum weight at which the aircraft is certified to take off. MLW is the maximum weight at which the aircraft is certified to land. MLW is typically lower than MTOW to ensure a safer landing margin, accounting for factors like landing gear strength and braking performance.

Q2: How often should an aircraft's weight and balance be updated?

The weight and balance records should be updated whenever a change occurs that affects the aircraft's empty weight or EWCG. This includes major repairs, modifications, equipment installations/removals, or significant changes in fixed equipment.

Q3: What happens if my aircraft's CG is too far aft?

An aft CG condition makes the aircraft less stable and harder to control, particularly during landing. It can lead to difficulties in flaring, reduced stall margin, and potentially a loss of control. The elevator effectiveness decreases, making it harder to keep the nose up.

Q4: What happens if my aircraft's CG is too far forward?

A forward CG condition makes the aircraft more stable but can result in sluggish control response and require more force on the controls to maintain pitch. It can also lead to higher approach speeds and difficulties in achieving the desired landing attitude.

Q5: Can I use this calculator for any aircraft?

This calculator provides the fundamental calculations. However, you MUST use the specific Empty Weight, EWCG, arms, and allowable CG ranges provided in YOUR aircraft's official Pilot's Operating Handbook (POH) or Type Certificate Data Sheet (TCDS). Aircraft types vary significantly.

Q6: What is the "datum" in weight and balance calculations?

The datum is an imaginary vertical line or plane used as the zero reference point for measuring the arms (horizontal distances) of all weights on the aircraft. Its location is defined in the aircraft's POH and is crucial for consistent calculations.

Q7: How do I calculate the CG of baggage or passengers?

Your aircraft's POH will typically provide the arms for specific baggage compartments and passenger seats. If loading multiple passengers or baggage items, you may need to calculate the combined moment and weight of those items to find their collective CG before adding it to the aircraft's total moment and weight.

Q8: What does "% MAC" mean for CG?

% MAC (Mean Aerodynamic Chord) is another way to express the CG location, often used in performance-critical aircraft like jets. It relates the CG position to the aircraft's wing chord length, providing a standardized reference independent of specific arm measurements from a datum.