Average Cost
The average cost method keeps track of the cost for each stock-type item. Each time you make a purchase, the average cost for that item is recalculated.
Example-Average Cost
You buy three widgets for $2.00 each and three for $1.00 each. To get the average cost, add together the amount you paid for each item, and divide by the total number of items. The average cost would be $1.50
($9.00 / 6 Widgets = $1.50).
Example-Adjustments to Inventory
Now, three widgets are stolen from your warehouse. You would have to make an inventory adjustment through the Tasks menu. The average cost is still $1.50 because the average cost doesn't change when your inventory adjusts down.
Example-Cost of Goods Sold
You manage to sell your three remaining widgets for $6 each. The Cost of Goods Sold would be $4.50 or Average Cost ($1.50) times Quantity (3).