Cessna 172 Weight and Balance Calculator
Ensure your flight is safe, legal, and within limits.
1. Aircraft Basic Empty Weight
2. Load Details
Formula: CG = Total Moment / Total Weight
| Item | Weight (lbs) | Arm (in) | Moment (lb-in) |
|---|---|---|---|
| TOTALS | 0 | – | 0 |
* Arms are standard Cessna 172 generic values. Verify with your specific Pilot's Operating Handbook (POH).
CG Envelope Graph
What is a Cessna 172 Weight and Balance Calculator?
A Cessna 172 weight and balance calculator is an essential flight planning tool used by pilots to ensure their aircraft is loaded safely and legally within the manufacturer's specified limits. Unlike a car, an airplane behaves very differently depending on how heavy it is and where that weight is located.
Every Cessna 172 aircraft leaves the factory with a specific empty weight and center of gravity (CG). Whenever you add fuel, passengers, or baggage, the center of gravity shifts. If the CG moves too far forward, the aircraft may be difficult to flare during landing. If it moves too far aft, the aircraft can become unstable and impossible to recover from a stall. This cessna 172 weight and balance calculator simplifies the complex math required to verify these parameters.
Student pilots, flight instructors, and private owners use this tool before every flight to calculate the Gross Weight and the Center of Gravity (in inches aft of the datum) to confirm the aircraft falls within the "Normal" or "Utility" operating envelopes.
Cessna 172 Weight and Balance Formula
The physics behind the cessna 172 weight and balance calculator is based on the principle of moments. The aircraft balances like a seesaw on its center of lift.
The Core Equations
To find the Center of Gravity, we use three simple steps:
- Calculate Moment: Weight × Arm = Moment
- Sum Totals: Add all weights to get Total Weight, and all moments to get Total Moment.
- Calculate CG: Total Moment ÷ Total Weight = Center of Gravity (CG)
Variable Definitions
| Variable | Meaning | Unit | Typical C172 Range |
|---|---|---|---|
| Weight | Force of gravity on an object | lbs | 1,400 – 2,550 lbs |
| Arm | Distance from the Reference Datum | inches | 35″ – 123″ |
| Moment | Rotational force (Torque) | lb-in | 50,000 – 120,000 |
| Datum | Imaginary vertical plane (usually firewall) | N/A | 0″ |
Table 1: Key variables used in weight and balance calculations.
Practical Examples: Using the Calculator
Example 1: The Training Flight (Utility Category)
A student and instructor are going out for spin training. For this, they need to be in the Utility Category (lighter weight, forward CG).
- Aircraft Empty: 1,450 lbs @ 39.5″ Arm (57,275 Moment)
- Front Seats: 340 lbs (Instructor + Student)
- Rear Seats: 0 lbs
- Fuel: 30 Gallons (180 lbs)
- Baggage: 0 lbs
Result: The Total Weight is 1,970 lbs. The calculated CG is approximately 39.8″. This falls safely within the Utility category limit, allowing for maneuvers like spins.
Example 2: The Cross-Country Trip (Normal Category)
A pilot is taking three friends on a trip. This scenario often pushes the limits of the cessna 172 weight and balance calculator.
- Aircraft Empty: 1,450 lbs
- Front Seats: 350 lbs
- Rear Seats: 300 lbs
- Baggage: 40 lbs
- Fuel: 40 Gallons (240 lbs)
Result: Total Weight is 2,380 lbs. While this might be under the max gross weight for some C172 models (like the 172S), older models (like the 172N with a 2,300 lb limit) would be overweight. The CG shifts aft significantly due to the rear passengers and baggage.
How to Use This Cessna 172 Weight and Balance Calculator
- Locate Aircraft Basic Empty Weight & Moment: Find the "Weight and Balance Sheet" in your specific airplane's POH or paperwork. Enter these values in the first section.
- Enter Passenger Weights: Input the weight of the pilot and front passenger combined. Do the same for rear passengers.
- Input Fuel: Enter the fuel in gallons. The calculator automatically converts this to weight (6 lbs/gallon).
- Add Baggage: Enter baggage weights for Area 1 and Area 2. Be mindful of the 120lb limit.
- Analyze the Graph: Look at the "CG Envelope Graph" below the results.
- Green Point: You are within the safe envelope.
- Red Point: You are outside the envelope. DO NOT FLY.
Key Factors That Affect Weight and Balance Results
Several variables can drastically change your output in the cessna 172 weight and balance calculator:
1. Fuel Burn
As you fly, you burn fuel. Since fuel is located at Station 48 (relatively forward compared to baggage), burning fuel reduces weight but can shift the CG aft. Always calculate your landing weight and CG as well as takeoff values.
2. Baggage Placement
Baggage Area 2 (Station 123) has the longest arm. Even a small amount of weight here generates a huge moment, shifting the CG aft rapidly. 50 lbs in the back has the same leverage effect as 150+ lbs in the front seats.
3. Aircraft Modifications
New avionics, wheel fairings, or upgraded engines change the Basic Empty Weight. Always use the most current weight and balance record, not the one from the original manual.
4. Temperature (Density Altitude)
While not a direct weight factor, high temperature reduces engine performance. If your cessna 172 weight and balance calculator shows you are at max gross weight on a hot day, your takeoff roll may exceed the runway length.
5. Unit Conversions
Fuel is often sold in Liters in some countries but calculated in Gallons or Pounds. Using the wrong density (e.g., Jet A density vs Avgas) will lead to dangerous calculation errors.
6. Zero Fuel Weight
While less critical in small Cessnas than jets, ensuring your structural weight without fuel is within limits prevents wing stress. The main concern in a C172 is usually Max Gross Weight.
Frequently Asked Questions (FAQ)
What is the max gross weight of a Cessna 172?
It depends on the model. A Cessna 172N typically has a max gross weight of 2,300 lbs. The newer Cessna 172S Skyhawk SP has a max gross weight of 2,550 lbs. Always check your POH.
Can I fly if the CG is outside the envelope?
No. It is illegal and extremely dangerous. An aft-CG airplane is unstable and may not recover from a stall. A forward-CG airplane may not have enough elevator authority to land safely.
How much does Avgas weigh?
Standard aviation gasoline (100LL) weighs approximately 6.0 pounds per US gallon at standard temperatures. This calculator uses this standard value.
What is the difference between Normal and Utility category?
Normal category allows for standard maneuvers and limited bank angles. Utility category (usually lighter weight and forward CG) permits limited aerobatics, including spins and banks greater than 60 degrees.
Does this calculator work for a Cessna 152 or 182?
No. Every aircraft has different "Arms" (stations) and limits. Using a cessna 172 weight and balance calculator for a 182 will result in dangerous data because the wheels, seats, and fuel tanks are at different distances from the datum.
What happens if I overload the baggage compartment?
Exceeding the 120 lb limit in the baggage area can cause structural damage to the floor, even if the total aircraft weight is legal. It also creates a severe aft-CG tendency.
Why does the Moment value matter?
The moment is the raw data used to find the CG. While pilots talk in terms of "CG inches," the math relies on summing the moments. It represents the "rotational force" around the datum.
How do I calculate landing weight?
Take your takeoff weight and subtract the weight of the fuel you expect to burn during the flight. Re-run the calculation with the lower fuel amount to ensure your Landing CG is still within limits.
Related Tools and Internal Resources
Enhance your flight planning with our suite of aviation tools:
- Density Altitude CalculatorCalculate aircraft performance on hot days.
- Crosswind Component ToolDetermine safe landing limits.
- Fuel Burn EstimatorPlan range and endurance accurately.
- Ground Speed CalculatorCompute true speed over the ground.
- Holding Pattern VisualizerEntry procedures made simple.
- VFR Flight Plan ChecklistStep-by-step preflight guide.