Supply chain glossary

Inventory Turnover

How inventory turnover measures the speed at which stock is sold and replaced, why the ratio needs a benchmark, and how to read it without cutting availability.

06. august 2026

3 min

Inventory Turnover

Inventory turnover is a ratio showing how many times a company sells and replaces its average inventory over a given period, usually a year. It is calculated as cost of goods sold divided by average inventory value, and it converts capital tied up in stock into a single figure comparable across periods, categories and locations.

A higher ratio means the same revenue is produced with less capital locked in stock, but the figure has no universally correct value: fresh food turns over fifty times a year, spare parts twice, and both can be well managed. Turnover carries meaning only against a benchmark – the same category a year earlier, the same store format, the same segment of the assortment. Averaged across a whole catalogue it hides the two groups that matter most: the fast‑moving items carrying the revenue and the slow ones carrying the capital.

  • Inventory turnover = cost of goods sold ÷ average inventory value, both at cost and over the same period.
  • Average inventory = (opening + closing inventory) ÷ 2, or the mean of monthly closing balances where seasonality is strong.
  • Days of inventory = 365 ÷ inventory turnover – the same ratio expressed as days of cover.

The ratio is easy to improve for the wrong reason. Cutting stock raises turnover until availability starts to fall, and the margin lost on unserved demand appears nowhere in the formula, which is why turnover is read together with an availability metric rather than on its own. Two measurement details decide whether the numbers are comparable at all: inventory and sales must both be valued at cost, and the averaging window must match the seasonal profile – a year‑end balance taken after the Christmas peak has run down will overstate turnover for the whole year.

Inventory turnover in practice

Turnover is an outcome, not a lever. It moves when the parameters behind ordering move – service level targets, safety stock, order quantities and review cycles – so the way to raise it without losing sales is to recalculate those parameters per item and location instead of applying a blanket stock reduction. Veritico STOCK derives them from forecast error and lead time variability and writes them into the replenishment run, which shows up as inventory value falling while availability holds. See demand forecasting and inventory optimization, replenishment and allocation management, and the Albert case study.

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