Cost is the basis for inventory valuation. However not all costs are involved in determining the cost of inventories.
The costs known as product costs are capitalized in the Inventories account on balance sheet include
purchase cost
conversion cost
allocation of fixed production overhead based on normal capacity levels
other costs necessary to bring the inventory to its present location and condition
By capitalizing inventory cost as an asset, expense recognition is delayed until the inventory is sold
Not all inventory costs are capitalized: some are recognized as expense in the period incurred. These are the period costs:
unallocated portion of fixed production overhead
abnormal waste of materials, labor, overhead
storage costs (unless required as part of the production process)
administrative overhead
selling costs