The computational method involves calculating the moments for the various loads to be carried, finding the total weight and moment of the loaded airplane, and then calculating the loaded airplane's center of gravity location. The published weight and balance information for the aircraft contains the stations at which the various loads will be carried.
Example| Item | Weight | x | Station | = | Moment |
| Empty Airplane | 1150 | x | 13.0 | = | 14950 |
| John | 190 | x | 12.6 | = | 2394 |
| Susie | 135 | x | 12.6 | = | 1701 |
| Flight Bag | 15 | x | 42.1 | = | 631.5 |
| Fuel (26 gals) | 156 | x | 13.6 | = | 2121.6 |
| Total | 1646 | 21798.1 |
The weight and balance data for the airplane gives the pilot the station locations and the airplane's empty weight and moment. The weight and moment of each load are determined and added together. By doing this, the total loaded airplane weight of 1,646 pounds is determined, and the total moment is 21,798.1 pound-inches.
Since weight times station is moment, station is equal to moment divided by weight. To find the loaded airplane's CG, we would divide 21,798.1 pound-inches by 1,646 pounds. The result is 13.24 inches.
At this point, we refer to the weight and balance data for the airplane to verify we are within the weight and balance limitations. The maximum structural limitation is listed as 2,600 pounds. Our takeoff weight of 1,646 is well under this limitation.
The CG range for the airplane at 1,646 pounds is 11.0 to 16.3 inches. Our CG of 13.24 inches lies within this range.
Adding and Removing Items
The computational method can also be used to add or remove items after the weight and balance has been calculated. For example, if we discover that Susie has another bag we were previously unaware of, it would not be necessary to redo the weight and balance computations from scratch. The bags weight and moment could simply be added to the previous totals.
| Item | Weight | x | Station | = | Moment |
| Previous Total | 1646 | 21798.1 | |||
| + Susie's Bag | 35 | x | 42.1 | = | 1473.5 |
| New Total | 1681 | 13.84 | 23271.6 |
The new weight of 1,681 pounds and CG location of 13.84 inches are both still within limits.
Removing an item is performed the same way. Subtract the weight and moment of the removed items from the previous total weight and moment.
| Item | Weight | x | Station | = | Moment |
| Previous Total | 1681 | 23271.6 | |||
| - Removed Weight | 10 | x | 42.1 | = | 421 |
| New Total | 1671 | 13.67 | 22850.6 |
Moving Items
The computational method can be used to find the effect of moving an item by removing the item from the previous location, then adding it to the new location. For example, if John decided he would rather sit in the back seat, we could find the new weight and balance by removing him from the front seat, then adding him to the rear seat.
| Item | Weight | x | Station | = | Moment |
| Previous Total | 1671 | 22850.6 | |||
| - John | 190 | x | 12.6 | = | 2394 |
| + John | 190 | x | 30.7 | = | 5833 |
| New Total | 1671 | 15.73 | 26289.6 |
The total weight is still 1,671 pounds. However, the CG location has moved to 15.73 inches. The weight does not exceed the maximum weight, and the CG location is within limits. It is ok for John to sit in the back seat.