ERPLY keeps inventory using FIFO (First In, First Out) method. All incoming goods are registered as batches. Each sold, written-off or transferred item is subtracted from the oldest available batch. Hence, oldest inventory items (that arrived first) are also sold first.
COGS (Cost of Goods Sold) is calculated by adding up the costs of each individual sold item.
The remaining value of your inventory is the total cost of all batches still in stock.