Weight & Balance Calculator

For each loaded item, moment = weight × arm (arm = distance in inches or cm aft of the datum). Add up all weights to get total weight, add up all moments to get total moment, then CG = total moment ÷ total weight. That one division is the entire "formula" — everything else is bookkeeping. This tool does the bookkeeping for you and plots the result against your CG envelope.

The standard workflow is: (1) list every item — empty aircraft, pilot and passengers, baggage, fuel; (2) multiply each weight by its arm from the POH to get moments; (3) total the weights and moments; (4) divide total moment by total weight to get the CG; (5) check that weight is under maximum takeoff weight and the CG point falls inside the CG envelope; (6) repeat the check for the landing condition after planned fuel burn. This suite automates all six steps, including the fuel-burn shift.

The CG envelope is the approved region on a chart of CG position (horizontal axis) versus aircraft weight (vertical axis). If your computed (CG, weight) point falls inside the envelope, the loading is within certified limits. The left edge is the forward CG limit, the right edge the aft limit, and the top edge is maximum weight. The chart on this page draws your envelope and plots your zero-fuel, takeoff, and landing points so you can see margins at a glance.

The datum is an imaginary reference plane the manufacturer picks (often near the firewall or nose) from which all distances are measured. The arm (or station) is the distance of an item aft of the datum, usually in inches. Items ahead of the datum would have negative arms, but in light aircraft every station is aft of the datum, so arms are positive numbers like 37" for front seats in a Cessna 172.

Both are dangerous, for different reasons. Forward CG (nose-heavy) increases stall speed, needs more elevator to flare, and can make the nosewheel slam down — in the extreme you cannot rotate at all. Aft CG (tail-heavy) reduces pitch stability: the airplane is twitchy, stalls more abruptly, and spin recovery is degraded or impossible. Never fly outside either limit — "close enough" is not a category.

%MAC expresses the CG as a percentage of the wing's Mean Aerodynamic Chord: %MAC = (CG − LEMAC) ÷ MAC × 100, where LEMAC is the leading edge of the mean aerodynamic chord. Typical light-aircraft CG ranges sit around 15–30% MAC. Enter your LEMAC and MAC (from the POH weighing section) in the calculator to get the %MAC readout alongside inches.

Fuel has an arm too, so as it burns off the CG shifts. In most light aircraft the fuel arm is aft of the typical CG, so burning fuel moves the CG forward — but not always, and in some aircraft the shift is aft. The fuel-burn mode on this page computes your takeoff CG and landing CG from your planned burn and shows both on the envelope chart. Always check the landing condition: a loading that is legal at takeoff can drift out of the envelope by landing.

Zero fuel weight is the aircraft plus everything except usable fuel — crew, passengers, baggage. Some aircraft (notably the Cirrus SR22, with a 3400 lb zero-fuel limit) have a maximum zero fuel weight to protect the wing structure: fuel in the wings relieves bending loads, so the fuselage contents alone are limited. The calculator shows your zero-fuel condition and checks it against the limit when the preset defines one.

Sure — using the C172S preset on this page: empty 1663 lb (moment 67,303), pilot + front passenger 340 lb at arm 37" (moment 12,580), 50 gallons of fuel = 300 lb at arm 48" (moment 14,400). Totals: weight 2303 lb, moment 94,265, CG = 94,265 ÷ 2303 = 40.93". At 2303 lb the forward limit is 38.24" and the aft limit 47.3", so the point is inside the envelope with 2.7" of forward margin. Try it live with the preset.

Yes — switch the unit toggle to metric. Weights are entered in kg, arms in cm, and fuel in liters (converted at 0.719 kg/L, the metric equivalent of the standard 6.0 lb/gal for avgas). The math is identical; only the units change. Useful for aircraft with metric POH supplements and for training outside the US.

This page includes a printable W&B sheet: fill in your loading, then use the Print button (or Ctrl/Cmd+P) to get a clean one-page loading form with every station, totals, CG, envelope verdict, and a signature/date line — the same layout flight schools use. It replaces the spreadsheet for ramp use, and because everything runs in your browser there is nothing to download or install.

Yes. Regulations (e.g. 14 CFR 91.103 in the US) require the pilot in command to become familiar with all available information concerning the flight, including weight and balance — and examiners will ask for it on a checkride. Any change in passengers, baggage, or fuel is a new calculation. This tool makes the "every flight" part take seconds instead of minutes.

Useful load = maximum takeoff weight − empty weight. It is everything you are allowed to add: crew, passengers, baggage, and usable fuel. Example: a C172S at 2550 lb MTOW with a 1663 lb empty weight has 887 lb of useful load. With full fuel (336 lb) that leaves about 551 lb for people and bags — the classic "full fuel or full seats, not both" tradeoff.

Do not fly until it is inside. Practical fixes: reduce weight (less fuel — carry what the trip needs plus reserves, not full tanks by habit), move weight (heavy bags from the aft baggage area to the rear seat area or vice versa shifts the CG), or leave something behind. Re-run the numbers after every change, and re-check the landing condition after the planned fuel burn.

The presets use representative sample values (arms, envelope corners, and sample empty weights) compiled from published POH and type-certificate data — they are correct as worked examples and for training, but your specific airframe's empty weight, moment, and equipment list come from its own weight and balance records. For real flight planning, overwrite the empty-weight row and verify every arm and envelope limit against your aircraft's POH/AFM.

No. This is a planning and training aid: it does the arithmetic and draws the chart, but the authoritative limits are the charts and tables in your aircraft's POH/AFM and its individual weight and balance records. Weight and balance errors can be fatal — always cross-check the final numbers against your POH before flight.