Aircraft Weight and Balance Calculator
Centre of gravity = total moment ÷ total weight, where each item’s moment is its weight × arm; a loading is legal only if both total weight and CG fall inside the envelope in your POH or AFM.
| Item | Weight | Arm | Remove |
|---|---|---|---|
For general informational use. Verify critical aviation calculations and weather with an authoritative source.
Worked loading example and fuel burn
An example four-seat single, using figures for illustration only. Your aircraft’s empty weight, arms and limits are in its own weight and balance report and flight manual.
| Item | Weight (lb) | Arm (in) | Moment (lb-in) |
|---|---|---|---|
| Basic empty weight | 1,650 | 39.0 | 64,350 |
| Pilot and front passenger | 340 | 37.0 | 12,580 |
| Rear passenger | 170 | 73.0 | 12,410 |
| Fuel, 40 US gal at 6 lb/gal | 240 | 48.0 | 11,520 |
| Baggage | 50 | 95.0 | 4,750 |
| Take-off | 2,450 | 43.1 | 105,610 |
CG = total moment ÷ total weight = 105,610 ÷ 2,450 = 43.1 in aft of the datum.
Check the landing CG too
Burn 30 gal (180 lb) and only 10 gal remain. Landing weight is 2,270 lb and the moment falls by 180 × 48 = 8,640 to 96,970, so the CG moves forward to 42.7 in. In this example the fuel sits behind the CG, so burning it moves the CG forward. In aircraft where fuel is ahead of the CG, burning it moves the CG aft, which can push a tail-heavy load out of limits in flight even if it was legal at take-off.
Standard weights used in planning
- Avgas: about 6.0 lb per US gallon (0.72 kg/L).
- Jet A / Jet A-1: about 6.7 lb per US gallon (0.80 kg/L), varying with temperature.
- Engine oil: about 7.5 lb per US gallon.
- People and bags: use actual weights for small aircraft. Standard passenger weights are meant for larger aircraft and operators with approved programmes.
Why both limits matter
A CG too far forward needs more elevator to raise the nose, which can make the landing flare difficult and increases stall speed slightly. A CG too far aft makes the aircraft less stable in pitch and can make stall recovery difficult or impossible. Being under maximum weight does not make an out-of-limits CG safe.
Weight and balance in four columns
Every loading has a weight, an arm (distance from the reference datum) and a moment (weight × arm). Add the weights and moments, divide total moment by total weight and you have the centre of gravity. If the weight and CG fall inside the aircraft’s envelope, the loading is within limits.
How to use it
- Enter the basic empty weight and arm from the aircraft’s current weight and balance record.
- Enter each seat row, baggage area and fuel with the arms from the POH.
- Enter maximum weight and the forward and aft CG limits for that weight.
- Read total weight, total moment, CG and whether the loading is within your entered limits.
Method and calculation
Moment = weight × arm for each row. Total moment ÷ total weight = CG (in the same units as the arms). Fuel can be entered as US gallons at 6 lb each or litres at 0.72 kg each for Avgas. The tool checks the CG only against a simple forward/aft range; many aircraft have a sloping envelope, so always plot the result on the POH chart.
Worked example and practical notes
Empty 1,650 lb at 39.0 in; pilot and front passenger 340 lb at 37.0 in; rear seats 150 lb at 73.0 in; baggage 40 lb at 95.0 in; 40 gal fuel (240 lb) at 48.0 in. Total 2,420 lb, moment 103,200 lb-in, CG 42.64 in. With limits of 35.0–47.3 in and a maximum of 2,450 lb, the loading is within range.
Accuracy and practical tips
Check both take-off and landing weight and CG: fuel burn moves the CG during the flight. Use the actual empty weight from the aircraft records, not a brochure figure.
Generic arithmetic only. The aircraft flight manual and the aircraft’s own weight and balance report are the authority for every number.
Last reviewed: October 2026
Read the guide: Aircraft Weight and Balance: Calculating CG
Frequently asked questions
What is a moment?
Weight multiplied by its arm. Moments add up, and total moment divided by total weight gives the CG.
Where do I find the arms?
In the weight and balance section of the aircraft flight manual or POH, measured from the manufacturer’s datum.
Can I use kilograms and millimetres?
Yes, as long as every row uses the same units. The CG comes out in the arm unit you used.
Is a CG inside the min and max always safe?
Not always. Many envelopes are not rectangles, so plot the point on the POH envelope chart.