About this tool
Inventory Turnover Ratio Calculator is a free, in-browser tool that measures how many times you sell and replace your stock in a period. Enter the cost of goods sold (COGS) and your beginning and ending inventory, and it returns the turnover ratio, the days sales in inventory, and your average inventory. Nothing is uploaded — the math runs on your device.
Average inventory is (beginning + ending) ÷ 2. Inventory turnover is COGS ÷ average inventory — how many times the average stock was sold through. Days sales in inventory (DSI) is 365 ÷ turnover, the average number of days a unit sits before it sells. Using COGS rather than sales revenue keeps both sides of the ratio at cost, which is the standard, more accurate convention.
Use it to benchmark stock efficiency: a higher turnover and a lower DSI mean leaner, faster-moving inventory, while a low ratio can flag overstocking or slow sellers. Compare across periods or against industry norms to spot trends.