Free Weight & Balance Calculator

Aircraft Weight and Balance: How to Stay Within CG Limits

Weight and balance is one of the most critical pre-flight calculations a pilot performs. An overloaded aircraft may not reach takeoff speed within the available runway. An aircraft loaded outside its center-of-gravity (CG) envelope may be uncontrollable in flight. The FAA requires that weight and balance be computed before every flight — and it must be within the limits published in the POH. Our calculator computes total weight, total moment, and CG arm from your station weights and arms.

Weight and Balance Formula

Each loading station (pilot seat, rear seat, baggage, fuel) has a defined arm — the horizontal distance from the datum (a reference point, usually the firewall or nose). Multiply each station weight by its arm to get the moment. Add all moments and divide by total weight to find the CG location. This must fall within the forward and aft CG limits for your current weight.

Why CG Position Matters

• Forward CG — The aircraft is nose-heavy. It requires more back-elevator pressure to rotate and maintain level flight. In extreme cases, there may not be enough elevator authority to flare for landing.
• Aft CG — The aircraft is tail-heavy. It is less stable and more responsive to control inputs. In extreme cases, recovery from a stall or spin may be impossible. An aft-CG condition is generally more dangerous than a forward-CG condition.

Typical GA Aircraft Loading

For a typical single-engine GA aircraft (like a Cessna 172):

• Operational empty weight — Aircraft with required equipment, unusable fuel, and full oil (~1,650 lbs)
• Front seat — Pilot and copilot (~340 lbs at arm 85 inches)
• Rear seat — Passengers (~200 lbs at arm 118 inches)
• Fuel — 6 lbs per US gallon (~48 gallons × 6 = 288 lbs at arm 96 inches)
• Baggage — Zone A (~40 lbs at arm 149 inches)

Fuel Weight: Do Not Forget

Aviation gasoline (100LL) weighs approximately 6 pounds per gallon. A full 56-gallon tank adds 336 lbs — a significant load. Many pilots calculate weight at takeoff fuel but forget that CG shifts aft as fuel burns (because fuel tanks are typically forward of the CG). Check both takeoff and landing weight and balance.

The Loading Problem: Too Heavy

If your calculated weight exceeds max gross weight, you must reduce load. Options include:

• Carry minimum fuel (legal reserve plus planned fuel, no more)
• Reduce passenger count or ask passengers to take a later flight
• Leave non-essential baggage
• Defer maintenance items that add weight (if legal)

After Weight and Balance

With weight and balance confirmed, check density altitude — high DA further degrades performance on an already heavily loaded aircraft. Also check crosswind conditions for your departure and destination runways. Together, these three calculations form the core of safe pre-flight planning.

Defaults shown are approximate values for a generic ~2,550 lb GA aircraft. Always use the specific weights, arms, and CG envelope from your aircraft POH Section 6 (Weight and Balance). Incorrect data produces incorrect results.