What is the inventory turnover calculation

1) Inventory Turnover = Sales / Inventory

or

2) Inventory Turnover = COGS / Average Inventory

Typically the first calculation is more common.

Actually the typical answer is COGS / Average Inventory. Sales relates to the retail price of inventory. COGS and Inventory are expressed at cost or purchase price. It is also to remember to use Average Inventory to adjust for any changes in inventory during the accounting period. Using Ending Inventory can distort the turnover when there are significant increases or decreases in inventory during the accounting period.