Inventory Turnover Calculator

Inventory Turnover Ratio = Cost of Goods Sold (COGS) ÷ Average Inventory. Average Inventory = (Beginning Inventory + Ending Inventory) ÷ 2. Days on Hand (or Days Sales of Inventory) = 365 ÷ Inventory Turnover Ratio. COGS is the direct cost of producing goods sold during a period (from the income statement). Beginning Inventory is the inventory value at the start of the period (from the balance sheet). Ending Inventory is the inventory value at the end of the period. Average Inventory smooths seasonal fluctuations by using a midpoint, giving a more representative inventory level. A higher turnover ratio indicates inventory is selling quickly, suggesting efficient cash conversion and lower holding costs. A lower ratio may imply overstocking or slow-moving items, tying up cash. The ratio is dimensionless; Days on Hand converts it into the average number of days it takes to sell inventory, making interpretation more intuitive. Both metrics must be calculated over the same period (e.g., annual).

A 'good' inventory turnover ratio varies widely by industry, business model, and product type. Generally, a higher ratio indicates efficient inventory management and strong sales, while a lower ratio suggests overstocking, obsolescence, or weak demand. However, too high a ratio can mean stockouts and lost sales. For perishable goods (e.g., fresh food), turnover is often very high (e.g., 20-50 times per year) because inventory must move quickly. For durable goods (e.g., machinery or luxury items), turnover may be low (e.g., 2-6 times per year) due to longer shelf lives and higher unit values. Compare your ratio to your own historical trends rather than external averages, because company-specific factors like seasonality, supply chain strategy, and growth stage heavily influence the number. Days on hand complements the ratio: fewer days generally means faster cash conversion, but also requires reliable replenishment. Watch for distortions from inflation (COGS may rise faster than inventory values) or one-time events (e.g., large write-offs). Use consistent accounting methods (FIFO vs. LIFO) when comparing periods.

A common mistake is using total sales instead of COGS—sales include markup, inflating the ratio. Another error is using only ending inventory instead of averaging, which can misrepresent turnover if inventory fluctuates seasonally. For example, a retailer with high holiday inventory may show a low turnover if only ending inventory is used, even if sales are strong. Edge cases include negative COGS (rare, from returns exceeding costs) or zero average inventory (division by zero)—if inventory is zero, turnover is undefined and indicates no stock, likely a data error. Also, using different time periods (e.g., monthly COGS with annual inventory) skews results. Finally, ignoring inventory write-downs or write-offs can understate COGS and overstate turnover, masking obsolescence.

Cost of Goods Sold (COGS)

The direct costs attributable to the production of goods sold by a company, including materials and labor.

Average Inventory

The mean value of inventory over a period, calculated as (Beginning Inventory + Ending Inventory) ÷ 2.

Days on Hand (DOH)

The average number of days a company holds inventory before selling it, computed as 365 ÷ Inventory Turnover Ratio.

Inventory Turnover Ratio

A measure of how many times a company sells and replaces its inventory over a period, calculated as COGS ÷ Average Inventory.

Write-off

An accounting action to reduce inventory value due to obsolescence, damage, or theft, which increases COGS and lowers turnover.