Use Average Inventory for a Period-Based Turnover Ratio
Inventory turnover commonly divides cost of goods sold by average inventory. Using an average balance helps align a balance-sheet stock measured at specific dates with cost of goods sold measured across the whole period.
A higher turnover is not automatically better: stockouts, product mix, seasonality and margins matter. Compare the same accounting definitions across periods or similar businesses rather than using a fixed universal target.
Inventory turnover needs a consistent period and a sensible average inventory figure. Using only ending inventory can distort the ratio in a seasonal business, especially if the year-end balance is unusually high or low. Higher turnover can mean efficient inventory use, but extremely high turnover can also signal stockouts and lost sales. Compare the result with prior periods, similar businesses and the company's service level rather than assuming the highest number is always best.
Frequently Asked Questions
Why use COGS instead of revenue?
Inventory is generally carried at cost, so cost of goods sold provides a more consistent numerator for the standard turnover relationship.
What does inventory days represent?
It converts the turnover rate into an approximate number of days inventory remains on hand under the period assumptions.
Why use average inventory instead of ending inventory?
Average inventory better represents the amount carried through the period. A single ending balance can be unusually high or low because of seasonality or recent purchases.
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