Inventory Turnover Calculator
Calculate your inventory turnover ratio and average days inventory is held to assess how efficiently your business manages stock. Use it during financial reviews to spot overstocking, understocking, or slow-moving product issues.
About this calculator
The inventory turnover ratio measures how many times a business sells and replaces its entire inventory within a period. The formula is: Inventory Turnover = COGS / Average Inventory, where Average Inventory = (Beginning Inventory + Ending Inventory) / 2. COGS (Cost of Goods Sold) represents what it cost to produce or purchase the goods actually sold, making it a more accurate numerator than revenue. A higher ratio generally signals strong sales and lean stocking; a lower ratio can indicate overstocking, weak demand, or obsolescence risk. A complementary metric is Days Inventory Outstanding (DIO): DIO = 365 / Inventory Turnover. DIO tells you how many days, on average, inventory sits before being sold. Retailers, wholesalers, and manufacturers all benchmark these ratios against industry peers to set reorder points and optimize working capital.
How to use
A retailer has annual COGS of $480,000, beginning inventory of $60,000, and ending inventory of $80,000. Average Inventory = (60,000 + 80,000) / 2 = $70,000. Inventory Turnover = 480,000 / 70,000 ≈ 6.86 times per year. Days Inventory Outstanding = 365 / 6.86 ≈ 53.2 days. This means the business sells through its entire stock roughly every 53 days, or about 6.9 times a year. If the industry average is 8 turns per year, this retailer may be holding excess stock and should consider reducing order quantities or running promotions to clear slow-moving items.
Frequently asked questions
What is a good inventory turnover ratio for retail or manufacturing businesses?
A good ratio varies widely by industry. Grocery and fast-moving consumer goods retailers can turn inventory 15–30 times per year, while furniture or luxury goods retailers may turn it only 2–4 times. Manufacturing companies typically target 4–8 turns depending on production cycles. The key is to benchmark against direct competitors in your sector rather than a universal number. Consistently tracking your own trend over time is equally valuable for catching deterioration early.
How does a low inventory turnover ratio hurt business profitability?
Low turnover means capital is tied up in unsold goods, increasing holding costs such as storage, insurance, and the risk of spoilage or obsolescence. It also reduces cash flow available for other investments and can indicate poor demand forecasting or over-purchasing. In extreme cases, slow-moving inventory must be sold at a discount or written off entirely, directly hitting gross profit margins. Improving turnover frees up working capital and reduces the cost of carrying excess stock.
Why do businesses use average inventory instead of ending inventory in the turnover formula?
Using only ending inventory can distort the ratio because inventory levels fluctuate throughout the year due to seasonality, large orders, or year-end adjustments. Averaging the beginning and ending balances provides a more representative view of the stock level maintained during the period. For businesses with highly seasonal or volatile inventory, a monthly or quarterly average (summing each period's balance and dividing by the number of periods) gives an even more accurate denominator and a more reliable turnover figure.