Why is center of gravity important in aircraft?

Center of gravity determines how the aircraft handles. An aft CG (toward the tail) makes the aircraft more sensitive and potentially unstable: in extreme cases it can become impossible to recover from a nose-high attitude. A forward CG (toward the nose) makes the aircraft heavy on the nose and sluggish in pitch, and may prevent the pilot from raising the nose enough to flare for landing. Both conditions can cause loss of control. The CG limits in the POH are the safety boundaries within which the aircraft was designed and tested to operate.

What is the forward CG limit and what happens if you exceed it?

The forward CG limit is the most forward position the center of gravity can be while maintaining safe control of the aircraft. If the CG is too far forward, the nose is heavy, requiring excessive back pressure on the elevator or stabilator to maintain level flight. In extreme cases, the pilot may not be able to rotate during takeoff or flare sufficiently for landing. The forward limit is determined by elevator authority at the most critical flight conditions, typically minimum speed landing configuration with full flaps.

What is the aft CG limit and why is aft CG more dangerous?

The aft CG limit is the furthest rearward position the center of gravity can be. Aft of CG limit conditions are generally more dangerous than forward CG conditions because an aft-heavy aircraft becomes increasingly unstable in pitch. If the aircraft pitches nose-up, the tail-heavy condition tends to make it continue pitching nose-up rather than self-correcting. This can lead to loss of control from which recovery may be impossible. Aft CG also reduces the nose-down pitch authority needed to recover from stalls.

How accurate is the weight and balance calculator for my specific aircraft?

This calculator uses approximate preset arm values that are representative of each aircraft model but may differ from your specific aircraft due to installed equipment, modifications, and the specific empty weight from your aircraft's most recent weighing. The empty weight and arm in particular vary significantly between individual aircraft of the same model. Always obtain your aircraft's actual empty weight and empty arm from the weight and balance record in the maintenance logs and enter those values to replace the presets.

⚖️ Aviation Flight Planning · 14 CFR 91.9

Aircraft Weight and Balance Calculator: CG Envelope for US GA Pilots

The most complete free aircraft weight and balance calculator for US pilots. Preset profiles for Cessna 172, Cessna 182, Piper PA-28, and Beechcraft Bonanza. Enter your aircraft’s actual empty weight and arm, load each station, and see takeoff AND landing CG plotted on the same CG envelope chart. Shows moment and moment/1000. PDF load manifest included.

C172, C182, PA-28, Bonanza Takeoff and Landing CG on Same Chart Moment / Moment×1000 Useful Load Remaining IN / OUT OF LIMITS Badge PDF Load Manifest

Step 1: Select Aircraft and Enter Empty Weight

Aircraft Type

Preset arm values are representative. Always verify empty weight and arm from your aircraft’s weight and balance record.

Empty Weight (from W&B record)

lbs

From your aircraft’s current maintenance logbook W&B record.

Empty Arm (from W&B record)

Arm of empty aircraft from datum. From maintenance logbook W&B record.

Step 2: Enter Station Weights and Fuel

Enter weight in lbs for each occupied station. Fuel rows: enter usable gallons. Arms are pre-filled from preset aircraft data.

Station	Arm (in)	Weight / Qty	Moment

What Weight and Balance Means for US GA Pilots Before Every Flight

It was a warm Saturday at KVNY Van Nuys Airport. A Cessna 172 carried a 240-pound pilot, two 200-pound adults in the rear seat, full baggage, and full fuel. The total loaded weight was 2,744 pounds. Maximum gross is 2,550 pounds. The aircraft was 194 pounds over gross before it ever reached the runway. This scenario plays out every weekend at airports across the country, and most pilots involved genuinely believe they are within limits because they never ran the actual numbers.

Weight and balance is two separate checks that both must pass before any flight. The weight check confirms the aircraft does not exceed its maximum certificated gross weight. The balance check confirms the center of gravity (CG) falls within the forward and aft limits published in the Pilot’s Operating Handbook. Exceed either limit and the aircraft is not airworthy. 14 CFR 91.9 prohibits flight above certificated weight limits, and the CG limits are part of the aircraft’s type certificate.

The fundamental relationship: CG (inches) = Total Moment (inch-pounds) ÷ Total Weight (pounds). Moment = Weight × Arm. Arm is the distance in inches from the aircraft datum (a fixed reference point near the nose) to the center of that weight item. This calculator performs all those multiplications and divisions instantly, then plots the result against the published CG envelope.

Why Both Conditions Must Be Checked Separately

An aircraft can be within gross weight but have an out-of-limits CG. A C172 with three 150-pound passengers, all in the rear two seats, no front passenger, and baggage piled in the aft compartment will be well under gross weight but potentially with an extremely aft CG. An aft CG makes the aircraft pitch-sensitive and can reduce or eliminate the nose-down pitch authority needed for stall recovery. Conversely, a solo pilot in a heavily loaded aircraft with full forward-only ballast can be under gross weight but with the CG forward of the forward limit, making it difficult to raise the nose during rotation and landing flare.

How This Calculator Differs from Paper Methods

Traditional weight and balance uses a paper worksheet, a moment table from the POH, and a CG envelope chart. You calculate each station’s moment, sum them, find the CG, and plot it on the envelope graph. This calculator automates all of that and adds two features the paper method lacks: it plots both the takeoff CG and the landing CG (after fuel burn) on the same envelope chart, and it shows you the useful load remaining after your current loading. Both are valuable for planning that goes beyond a simple go/no-go check.

How This Aircraft W&B Calculator Works: Moment, CG, and Envelope Check

The calculator uses the standard aviation weight and balance formula applied to each loading station in sequence. Select your aircraft to pre-populate the station arm values. Override the empty weight and empty arm with the actual values from your aircraft’s current weight and balance record. Then enter the weight (in pounds) at each occupied station and the fuel in gallons at both takeoff and landing.

The Moment Calculation

For each station:

Moment (in-lbs) = Station Weight (lbs) × Station Arm (in)
Add all moments including the empty aircraft moment (empty weight × empty arm)
Add all weights
CG (in) = Total Moment ÷ Total Weight

The calculator also shows the moment divided by 1,000, which is how many Cessna and Piper POHs present the data in their moment tables. Using moment/1000 keeps the numbers in a manageable range: a Cessna 172 at 2,400 lbs with CG at 39 inches has a moment of 93,600 inch-pounds, which becomes 93.6 in the moment/1000 column. Both express the same thing.

The CG Envelope Check

After calculating the takeoff CG (with full planned fuel) and the landing CG (with the landing fuel load), the calculator checks each against the aircraft’s forward and aft limits at the corresponding weight. For aircraft with a trapezoidal envelope (where the limits change with weight, which is common), the limits are interpolated at the actual takeoff and landing weights. The results are displayed as IN LIMITS (green) or OUT OF LIMITS (red) for both conditions, and both points are plotted on the envelope chart simultaneously.

Why the landing CG matters: Fuel burns from the wing tanks during flight. Depending on where the fuel arm is relative to the CG, fuel burn can move the CG forward or aft. If the CG is forward of the fuel arm, burning fuel moves the CG aft. At an aft-limit envelope, this can push the landing CG outside limits even though the takeoff CG was fine. Checking both conditions catches this before it surprises you on final approach.

Understanding the CG Envelope: Forward and Aft Limits in US GA Aircraft

The CG envelope is a chart published in the POH that shows the allowable CG range (horizontal axis) at every weight from minimum to maximum gross (vertical axis). The shape of the envelope varies by aircraft type. Understanding the shape tells you something about the aircraft’s design and typical loading challenges.

Rectangular Envelope (Cessna 172)

The Cessna 172 has one of the simplest envelopes in US general aviation: the forward and aft CG limits are essentially constant across all weights from minimum flight weight to max gross. This makes the C172 forgiving from a loading standpoint: the limits do not tighten as you add weight. The forward limit is approximately 35.0 inches and the aft limit is approximately 47.3 inches, a 12-inch range. The most common loading error in a C172 is carrying three or four adult passengers plus heavy baggage, which pushes the CG aft, combined with low fuel (forward of the CG) which makes the aft shift worse as fuel burns.

Trapezoidal Envelope (Cessna 182, most taildraggers)

The Cessna 182 and many other aircraft have a trapezoidal envelope where the aft CG limit moves aft as weight increases. This seems counterintuitive but is an aerodynamic characteristic: at lighter weights the aircraft is more sensitive and needs tighter limits, while at heavier weights the aircraft is naturally more stable. The practical implication is that you should always check both the light-weight and heavy-weight limits, since the binding constraint shifts depending on your loading.

Why Forward CG Warnings Are Also Critical

Many pilots focus on aft CG problems because they are more inherently dangerous. But forward CG should not be dismissed. A Cessna 172 with a solo 250-pound pilot, full fuel, and maximum baggage all located forward of the datum will have a CG very near the forward limit. If the elevator authority is reduced by wear in the control system or restricted elevator travel, a forward CG can prevent full-flap landing flare and result in a hard touchdown. Always check both limits.

Three Real Weight and Balance Scenarios from US GA Flight Planning

Scenario 1: Cessna 172S, Weekend Trip from KSMO to KLAS (Family of Four)

A pilot plans a trip from Santa Monica to Las Vegas with spouse and two teenage children. Aircraft empty weight 1,698 lbs, empty arm 39.3 in. Is this loading legal?

Station	Arm (in)	Weight (lbs)	Moment (in-lbs)
Empty Aircraft	39.3	1,698	66,731
Pilot (front left)	37.0	185	6,845
Spouse (front right)	37.0	140	5,180
Rear seat left	73.0	130	9,490
Rear seat right	73.0	125	9,125
Baggage area 1	95.0	68	6,460
Fuel (36 gal usable)	48.0	216	10,368
TOTALS		2,562 lbs	114,199
RESULT: CG = 114,199 / 2,562 = 44.6 in (within 35.0 to 47.3 range – OK) but WEIGHT = 2,562 lbs EXCEEDS MAX GROSS 2,550 lbs by 12 lbs. Must offload baggage or reduce fuel by 2 gallons.

Scenario 2: Piper PA-28-180, Instructor and Student, Fuel for 2-Hour Lesson

A CFI (190 lbs) and a student (165 lbs) plan a 2-hour lesson from KSQL San Carlos. Aircraft empty weight 1,340 lbs, empty arm 86.3 in. Planning to take 40 gallons of fuel for reserves plus the lesson. Landing with 12 gallons.

Station	Arm (in)	Weight (lbs)	Moment (in-lbs)
Empty Aircraft	86.3	1,340	115,642
Front seats	85.5	355	30,353
Fuel at takeoff (40 gal)	95.0	240	22,800
Takeoff totals		1,935 lbs	168,795
CG at takeoff	168,795 / 1,935 = 87.2 in (within 83.0 to 93.0 range at 1,935 lbs) IN LIMITS
Fuel at landing (12 gal)	95.0	72	6,840
Landing totals		1,767 lbs	152,835
CG at landing	152,835 / 1,767 = 86.5 in (within 83.0 to 93.0 range at 1,767 lbs) IN LIMITS
RESULT: Both takeoff and landing within weight and CG limits. Plan is valid.

Scenario 3: Beechcraft Bonanza A36, Three Passengers, Fuel Management Alert

A Bonanza A36 pilot plans a trip with two adult passengers in the middle seats and one in the rear. Empty weight 2,180 lbs, empty arm 76.3 in. Full fuel (74 gallons) for a cross-country, landing with 20 gallons.

Station	Arm (in)	Weight (lbs)	Moment (in-lbs)
Empty Aircraft	76.3	2,180	166,334
Pilot (front left)	68.0	185	12,580
Middle seats	95.0	340	32,300
Rear (bag/pax)	121.0	175	21,175
Fuel (74 gal)	75.0	444	33,300
Takeoff totals		3,324 lbs	265,689
Takeoff CG	265,689 / 3,324 = 79.9 in (aft limit at 3,324 lbs is approximately 79.8 in) MARGINAL / AT LIMIT
Fuel at landing (20 gal)	75.0	120	9,000
Landing CG	(265,689 – 33,300 + 9,000) / (3,324 – 444 + 120) = 241,389 / 3,000 = 80.5 in EXCEEDS AFT LIMIT at 3,000 lbs
RESULT: Landing CG goes OUT OF LIMITS as fuel burns. The aft passengers must be rearranged or weight reduced before flight.

Expert Tips for Weight and Balance Loading at US Airports and FBOs

Always Get Your Aircraft’s Actual Empty Weight and Arm

The empty weight and arm in the POH from the manufacturer are the values at the time of delivery. Every aircraft since delivery has had equipment added, removed, or modified. Every repair involves some weight change. Your aircraft’s current empty weight and arm are in the weight and balance record in the maintenance logbooks, not in the original POH tables. The difference between the POH value and the current actual value can be 50 to 150 lbs for a 20-year-old GA aircraft. Always find and use the most recent W&B record entry.

Use Actual Passenger Weights, Not Standard Weights

The FAA allows airlines and charter operators to use standard passenger weights under specific conditions, but the FAA strongly recommends that GA pilots use actual weights. A pilot who estimates 170 lbs for each of three adult male passengers may be off by 60 to 90 total pounds if those passengers are each 200 lbs. On a hot day near gross weight, that error eliminates your performance margin. Ask passengers for their weights or keep a bathroom scale in your car at the airport. Most passengers are not offended if you explain it is a safety requirement.

Check Weight AND Balance: Do Not Stop at One

Many pilots check only whether total weight is under gross and stop there. Weight and balance is two separate calculations, and both must pass independently. A light solo pilot with heavy baggage all in the aft compartment can be well under gross weight but with an aft CG outside limits. A pilot who removes fuel to get under gross weight must verify the CG shifted in the right direction, because removing fuel from tanks that are aft of the CG shifts the CG forward, while removing fuel from forward tanks makes the CG go aft.

Check the Landing Condition When Fuel Burns to Known Locations

For flights longer than an hour, fuel burn moves the CG. Use this calculator to enter the planned fuel load at takeoff and at landing and verify both conditions are in limits. This is especially important for aircraft where the fuel arm is significantly different from the current CG, such as high-wing aircraft where the fuel is above the CG, or rear-fuselage-tank aircraft where the fuel is far aft. A loading that is fine at takeoff can move outside limits on a long flight.

Quick Reference: Weight and CG Limits for Common US Training Aircraft

The values below are general reference data for representative aircraft configurations. Your specific aircraft’s limits may differ due to model year, options, and STC modifications. Always use your aircraft’s type certificate data sheet and individual weight and balance record. Source: FAA Type Certificate Data Sheets (FAA.gov).

Aircraft	Max Gross Weight	CG Forward Limit	CG Aft Limit	Fuel Weight (6 lbs/gal)
Cessna 172S Skyhawk	2,550 lbs	35.0 in	47.3 in	53 gal = 318 lbs
Cessna 182T Skylane	3,100 lbs	~38.5 in (varies)	~47.3 in	92 gal = 552 lbs
Cessna 152	1,670 lbs	33.0 in	43.5 in	26 gal = 156 lbs
Piper PA-28-180 Cherokee	2,325 lbs	84.5 in	93.0 in	48 gal = 288 lbs
Piper PA-28R Arrow	2,650 lbs	86.0 in	94.0 in	72 gal = 432 lbs
Beechcraft Bonanza A36	3,650 lbs	67.5 in	80.0 in	74 gal = 444 lbs
Mooney M20J (201)	2,740 lbs	43.0 in	52.0 in	64 gal = 384 lbs
Diamond DA40	2,535 lbs	44.7 in	48.8 in	40 gal = 240 lbs

16 FAQs About Aircraft Weight and Balance, CG, and Load Limits

What is weight and balance in aviation?▼

Weight and balance refers to two separate preflight checks. Weight verifies the total loaded aircraft does not exceed maximum certificated gross weight. Balance verifies the center of gravity falls within the forward and aft limits. Both must pass. 14 CFR 91.9 prohibits flight above certificated weight limits and outside CG limits. The pilot in command is responsible for verifying compliance before every flight.

Why is center of gravity so important in aircraft?▼

CG determines stability and control authority. An aft CG makes the aircraft pitch-sensitive and potentially unstable: the nose-up tendency is self-reinforcing rather than self-correcting, which can lead to loss of control. A forward CG causes heavy nose-down handling and may prevent the pilot from raising the nose enough for normal rotation and landing flare. Both extremes can cause accidents. The CG limits in the POH are the boundaries within which the aircraft was designed and certified to fly safely.

How do you calculate CG for an aircraft?▼

CG equals total moment divided by total weight. Moment is weight multiplied by arm. Arm is the distance in inches from the aircraft datum to each weight item. Sum all weights. Multiply each weight by its arm to get that item’s moment. Sum all moments. Divide total moment by total weight to get CG in inches from the datum. Compare the CG to the forward and aft limits at the current weight.

What is an arm in aircraft weight and balance?▼

An arm is the horizontal distance in inches from the aircraft’s datum (a fixed reference point near the nose) to the location of a weight item. Each station (pilot seat, rear seats, baggage, fuel tank) has a specific arm published in the POH. Arms are always measured from the same datum. The arm values must come from your specific aircraft’s POH or weight and balance data sheet, not from a generic table, because they can vary with aircraft configuration and installed equipment.

What is maximum gross weight and can you exceed it?▼

Maximum gross weight (or maximum certificated takeoff weight) is the absolute upper weight limit for legal flight. It cannot be exceeded. Operating above this limit violates 14 CFR 91.9, reduces structural safety margins, increases stall speed, degrades climb performance, and extends landing distances. The maximum gross weight is part of the aircraft’s type certificate and is not a soft limit or a guideline: it is a regulatory requirement for every flight.

Does CG change during flight as fuel burns?▼

Yes. As fuel burns, the weight and moment from the fuel tanks decrease, shifting the CG. The direction of the shift depends on whether the fuel arm is forward or aft of the current CG. Pilots must verify the CG remains within limits throughout the entire flight, not just at takeoff. This calculator shows both takeoff CG and estimated landing CG on the same envelope chart, catching cases where a valid takeoff loading produces an out-of-limits landing condition as fuel burns.

What is the datum in aircraft weight and balance?▼

The datum is a vertical reference plane from which all arms are measured. Its location is defined by the aircraft manufacturer in the type certificate data sheet. Common datum locations include the firewall, the nose, or a point forward of the nose. The actual location does not matter for calculations as long as all arms are measured consistently from the same datum. All arms in the POH weight and balance section are from the same datum, so you can use them directly without knowing the physical datum location.

What is moment and moment over 1000 in weight and balance?▼

Moment is weight (lbs) times arm (in), expressed in inch-pounds. For large aircraft, moment values become very large numbers. Many POH weight and balance tables divide moment by 1,000, calling it “moment/1000” or “index units” to keep the numbers manageable. Both conventions give the same CG result: divide total moment by total weight, or divide (total moment/1000) by (total weight/1000). This calculator shows both the raw moment in inch-pounds and the moment/1000 value.

What is the forward CG limit and what happens when you exceed it?▼

The forward CG limit is the most nose-forward position the CG can be. It is determined by elevator authority at the minimum speed landing condition. Beyond the forward limit, the pilot may be unable to raise the nose sufficiently for a normal landing flare or may be unable to rotate the aircraft for takeoff. The forward limit is the boundary below which the aircraft design does not provide enough tail-down force to maintain control at low speeds.

Why is aft CG more dangerous than forward CG?▼

An aft CG is generally more dangerous because it creates an inherently unstable pitch condition. When the aircraft pitches nose-up, an aft-CG aircraft tends to continue pitching nose-up (positive feedback) rather than returning to level flight (negative feedback). This can lead to an unrecoverable stall. Forward CG limits elevator authority but the aircraft remains statically stable. NTSB accident data consistently identifies aft CG loading as a more common factor in fatal accidents than forward CG violations.

Is weight and balance required before every flight?▼

Yes. 14 CFR 91.9 requires compliance with weight and balance limits on every flight. Since loading changes on virtually every flight (different passengers, fuel loads, cargo), a W&B check should be performed before every departure. The FAA, AOPA, and every major pilot training organization recommend a full W&B calculation whenever the loading differs from the last verified calculation. Flying without checking is not just irresponsible: if an accident occurs, violation of 91.9 creates significant legal and insurance liability.

How accurate is this calculator for my specific aircraft?▼

This calculator uses preset arm values representative of each aircraft model, but your specific aircraft may differ due to installed avionics, modifications, and equipment changes since manufacture. The empty weight and arm in particular vary significantly between individual aircraft of the same model. Always obtain the actual values from your aircraft’s current weight and balance record in the maintenance logs and enter them in the empty weight and empty arm fields to replace the presets.

What is useful load in aviation?▼

Useful load is the maximum weight of all payload: pilots, passengers, baggage, and fuel combined. It equals maximum gross weight minus empty weight. A Cessna 172S with max gross of 2,550 lbs and empty weight of 1,700 lbs has 850 lbs of useful load. Full fuel (53 gal at 6 lbs/gal = 318 lbs) leaves 532 lbs for people and baggage. Four adults at an average 160 lbs each = 640 lbs, which exceeds the available 532 lbs. This is why some loading combinations are not mathematically possible in certain aircraft.

What fuel weight should I use for avgas in weight and balance?▼

The FAA standard weight for aviation gasoline (Avgas 100LL) is 6.0 pounds per gallon per AC 91-23B. Actual density varies slightly with temperature and blend, but 6.0 lbs/gal is the FAA-accepted planning standard. For Jet-A fuel, the standard weight is 6.7 lbs per gallon. This calculator uses 6.0 lbs per gallon for all aircraft (all preset profiles are piston-engine aircraft that use avgas).

What is zero fuel weight and why does it matter?▼

Zero fuel weight (ZFW) is the total aircraft weight without usable fuel. Some aircraft, particularly those with multiple fuel tanks or turbine engines, have a maximum zero fuel weight limit in the POH or type certificate. This limit protects wing structure: with no fuel dampening the wing bending loads, the structure sees higher stress. If your aircraft has a maximum ZFW, the non-fuel payload must be limited to keep ZFW within limits, even if takeoff weight is within gross weight limits.

How do I find my aircraft’s empty weight and arm?▼

Your aircraft’s current empty weight and arm are in the weight and balance record, a document in the maintenance logbooks and approved data package. This record must be updated whenever equipment is added or removed. The most recent entry in this record is the correct value to use. Do not use the empty weight from the original POH, which reflects the factory configuration and may differ significantly from your aircraft’s current empty weight after years of avionics upgrades and modifications.

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Legal Disclaimer and Editorial Transparency

This aircraft weight and balance calculator is a free educational reference tool published by USCalculators.com. The preset station arm values, CG envelope limits, and maximum gross weights are representative values based on publicly available FAA Type Certificate Data Sheets and Pilot’s Operating Handbooks for each aircraft model. These values are provided for educational and planning purposes only and may not reflect the exact specifications of your specific aircraft registration number, serial number, or installed equipment configuration.

Your aircraft’s actual empty weight, empty arm, station arm values, and CG envelope limits must be obtained from your specific aircraft’s current weight and balance record (in the maintenance logbook) and the approved flight manual or POH. FAA Type Certificate Data Sheets are available at FAA.gov. The FAA Weight and Balance Handbook (FAA-H-8083-1) is available at FAA.gov. The pilot in command is solely responsible for verifying that the aircraft is within all weight and balance limits before every flight. USCalculators.com has no commercial relationship with aircraft manufacturers or maintenance organizations. This page was reviewed by our aviation editorial team in August 2025.