Some companies have difficulty valuing inventory due to the type of inventory held, e.g. grocery stores or Future Shop.
Company calculates the total inventory sold & subtracts this amount from the first items of inventory purchased.
Like the name suggests.
The average cost of all inventory is used.
A company can actually identify which units are sold or left on hand fun inventory valuation, i.e. antique car dealership.
Companies will value their inventory @ the lower market price, i.e. PCs that become obsolete due to advances in the hi-tech frontier are no longer worth the price the company paid for them. Famous pessimistic accountants mantra: "We assume all losses & no gains".