Aircraft Weight & Balance Calculator

Frequently Asked Questions

How is the center of gravity calculated?

CG (in from datum) = Σ(weight × arm) ÷ Σ(weight). With pilot 170 lb @ 85 in, fuel 240 lb @ 95 in, baggage 50 lb @ 142 in: total moment = 14,450 + 22,800 + 7,100 = 44,350; total weight 460 lb; plus empty 1,500 lb @ 87 in (130,500) → CG = 174,850 ÷ 1,960 ≈ 89.2 in.

What is the CG envelope?

The POH/AFM publishes forward and aft CG limits at every weight. Loading must keep the computed CG inside that envelope at takeoff and at landing (after fuel burn) - both points must be checked.

What happens if CG is too far forward or aft?

Too forward: heavy elevator forces, longer takeoff, hard to flare. Too aft: stall recovery becomes difficult or impossible, and pitch stability degrades. Aft CG is the more dangerous condition.

This is for study only - what do I use in real flight?

Always use the aircraft's current empty weight & moment from the latest weighing, the official POH loading chart, and verify with the FBO if any equipment changed. This calculator is educational; verify with the POH/AFM before any actual flight.

Provided by AllCalculators.io
Free online calculators for everyday. No registration required.

Educational only. Not for flight or navigation operations.

Aviation & Marine Disclaimer: Educational only. Not for flight or navigation operations.

This calculator is for educational and informational purposes only and is not a substitute for official flight or navigation planning. Always use current performance charts, an approved POH/AFM, certified navigation tools, and follow all applicable FAA, ICAO, USCG, and other regulatory guidance. Verify all results independently before operating any aircraft or vessel.

JavaScript is required to use the interactive calculator above. The questions and answers below remain readable without JavaScript.

How This Calculator Works

Weight and balance is the single most important pre-flight calculation in light-aircraft operation. Every airframe is certified with a center-of-gravity (CG) envelope - a forward and aft limit, often graphed against gross weight - and the aircraft handles and stalls predictably only when the loaded CG falls inside that envelope at a weight at or below max takeoff weight (MTOW). This calculator sums the moments from up to six stations (typical for a four-seat single: empty aircraft, front seats, rear seats, baggage, fuel) and divides by total weight to find the loaded CG. It also flags whether your CG is inside the supplied fwd/aft limits and whether you have exceeded max gross. Use it for planning study - verify every number against your specific aircraft's Pilot Operating Handbook (POH) or Aircraft Flight Manual (AFM) weight-and-balance section before flight.

Formula / Method

Moment = weight × arm. Arm is the horizontal distance (inches) from the reference datum to the item; the datum is defined by the manufacturer (firewall, leading edge, propeller hub, etc.). Total moment Σ(W × A) divided by total weight ΣW gives the loaded CG arm. The aircraft is legal to fly when (a) total weight ≤ MTOW and (b) fwd limit ≤ CG ≤ aft limit at that weight. Many envelopes are trapezoidal - the aft limit moves forward at heavier weights - so you must check against the limits valid for your loaded weight, not the absolute extremes.

Worked Example

A Cessna 172 with empty weight 1,450 lb at arm 37.0 in (moment 53,650 lb-in), two front-seat occupants totalling 340 lb at 37.0 in (12,580), one rear-seat passenger 170 lb at 73.0 in (12,410), 120 lb baggage at 95.0 in (11,400), and 38 gal usable fuel = 228 lb at 48.0 in (10,944). ΣW = 2,308 lb (under 2,400 MTOW ✓); ΣM = 100,984 lb-in; CG = 100,984 ÷ 2,308 ≈ 43.75 in. If the published envelope at 2,308 lb is 35.0–47.3 in, the aircraft is within limits. Burn off 20 gal in cruise (−120 lb at 48.0 in) - CG shifts slightly aft, recheck for landing.

Common Mistakes

Using the wrong empty weight - aircraft are reweighed when equipment changes; always use the current weight-and-balance sheet, not the factory figure. Forgetting fuel burn shifts the CG during flight; if you are near a limit at takeoff, recheck the landing condition. Confusing arm units - some manuals use inches, others millimetres; mixing them silently moves the CG by 25×. Treating "total moment" figures from the POH as additive without dividing by 1,000 (a common POH convention to keep numbers manageable). Loading heavy items in the baggage compartment to balance a light pilot - almost always pushes the aft CG limit, degrades stall recovery, and is a leading cause of loss-of-control accidents.

Tips & FAQ

Why does CG matter so much? A forward CG makes the aircraft more stable but increases stall speed and elevator force on landing; an aft CG reduces stability, can make the airplane uncontrollable in a stall, and in extreme cases prevents recovery from a spin. What is the "envelope"? A graph in the POH plotting allowable CG vs. weight - this calculator accepts simple fwd/aft limits; for full envelope checks, read your weight you computed back to the POH chart. How precise must I be? To the nearest pound and tenth of an inch is standard; the math is simple but the inputs matter. Do I need to do this every flight? Whenever loading changes meaningfully - passengers, baggage, fuel quantity, equipment. Disclaimer: this tool is for planning study only; verify with your current POH/AFM and a CFI before flight.

Aircraft Weight & Balance Calculator

Frequently Asked Questions

Related Aviation & Marine Calculators