Inventory Turnover

Inventory turnover is a metric that measures how many times a company sells and replenishes its stock over a given period, usually a year. It answers a concrete business question: is the inventory sitting in my warehouse moving quickly, or is it standing still and tying up capital?

The classic formula divides the cost of goods sold (COGS) by the average inventory for the period. A result of 6, for example, means the company turned over its entire stock six times during the year. High turnover signals brisk sales and little capital trapped in merchandise; low turnover usually points to overstock, obsolete products or weak demand.

Measuring and comparing this metric consistently across categories, branches and periods is exactly what an analytics platform like Metrix solves, centralizing sales and inventory data to calculate the metric without manual spreadsheets.

How it is calculated and what it means

Inventory turnover comes from a simple formula: turnover = cost of goods sold / average inventory. Average inventory is calculated by adding the opening and closing stock for the period and dividing by two, which smooths out seasonal swings. The result is a number of times (for example, 4 or 8), not a percentage.

One key point to avoid confusion: the numerator is the cost of sales, not revenue. Using sales revenue (which includes margin) artificially inflates the metric and makes it impossible to compare across companies. Both COGS and inventory must be measured at cost for the math to be correct.

A sister metric widely used in LATAM is days of inventory (DSI, or "days sales of inventory"), which translates turnover into time: days = 365 / turnover. A company with a turnover of 6 holds roughly 60 days of stock on average. Talking in days is usually more intuitive for operations and sales teams than talking in "turns".

Why it matters to the business

Turnover is one of the most closely watched metrics in retail, consumer goods and distribution because it ties directly to working capital. Every dollar sitting in merchandise is a dollar that is not available for anything else. Healthy turnover frees up cash, reduces obsolescence risk and lowers storage costs. In categories with expiration dates (food, pharmacy, cosmetics), slow turnover also translates into direct losses from products that expire.

But "higher" is not always better. Turnover that is too high can hide a problem: if stock flies off the shelves because it is chronically low, the company ends up with stockouts and loses sales it cannot even record. The right balance depends on the industry and is managed together with safety stock and the target service level.

A concrete example

A supermarket chain in Argentina closes the year with COGS of $12 million and average inventory of $1.5 million. Its turnover is 12 / 1.5 = 8 times, equivalent to about 46 days of stock. If the beverages category turns 20 times (replenishing every 18 days) but home appliances turn only 3 times (every 120 days), the analysis reveals where capital is tied up. With that information, the purchasing team can adjust replenishment and renegotiate supplier terms for the slow categories.

Common mistakes when using it

• Mixing revenue and cost in the formula (the most frequent mistake).
• Calculating a single company-wide turnover and making decisions with it, instead of breaking it down by category or SKU.
• Ignoring seasonality: comparing December (peak demand) against February distorts the average.
• Forgetting the industry context: a wholesale distributor and a jewelry store have very different target turnovers and are not comparable.

How it differs from similar metrics

Turnover answers "how fast is my stock moving?", while GMROI adds the profitability dimension (a product can turn slowly but leave a lot of margin) and fill rate measures customer service. All three are best read together, not in isolation.