Inventory Turnover Ratio is:

Inventory turnover is a financial metric that quantifies the frequency at which a company's inventory is converted into revenue from operations within a specific accounting period. This key ratio reflects the correlation between the cost of revenue from operations and the average inventory level during the same period.
Inventory Turnover Ratio = Cost of Revenue from Operations / Average Inventory
Where average inventory refers to arithmetic average of opening and closing inventory, and the cost of revenue from operations means revenue from operations less gross profit.