Inventory turnover ratio measures how many times you sell through your entire inventory in a period: cost of goods sold divided by average inventory value. A ratio of 6 means you sold and replaced your stock six times this year. It is the single fastest health-read on whether your cash is working or napping on shelves.
The formula, with a worked example
Inventory turnover = COGS / average inventory value
Average inventory = (beginning inventory + ending inventory) / 2, both at cost, not retail.
Example: your store’s COGS last year was $180,000. Inventory was worth $36,000 on January 1 and $24,000 on December 31, so average inventory is $30,000. Turnover = 180,000 / 30,000 = 6 turns per year.
To convert to time: 365 / turnover = days to sell through, here 365 / 6, about 61 days of stock on hand on average. (That figure is the accounting cousin of days of inventory cover, which computes the same idea per SKU from live unit velocity.)
Use COGS, not revenue: revenue inflates the ratio by your margin and makes fat-margin businesses look faster than they are.
What a good ratio looks like
There is no universal good, only good-for-your-model:
- 2 to 4: normal for furniture, jewelry, high-ticket slow movers. Below 2, cash and storage costs deserve a hard look.
- 4 to 8: the healthy band for most small and mid-size ecommerce catalogs.
- 8 to 15: fast apparel, consumables, trend goods. Efficient, but check you are not stocking out between orders.
- 15+: grocery-speed. In ordinary retail this often signals under-stocking rather than brilliance, stockouts have costs too.
Direction beats level: a ratio drifting down quarter over quarter means inventory is accumulating faster than sales justify, deadstock forming in slow motion.
Reading it as a multichannel seller
Two adjustments matter once you sell on several channels:
Compute it on the whole pool. One stock pool serves Amazon, eBay, and your store; turnover computed per channel misreads the same inventory several ways. Combined COGS over the shared pool’s average value is the true number.
Let the catalog distribution warn you. The blended ratio hides the story: a healthy 6 can be five SKUs turning 20 while forty SKUs turn once. Ranking SKUs by turnover (or its operational proxy, per-SKU days of cover) finds both problems, the fast movers that deserve deeper stock and the sleepers eating your storage. Unifystock’s analytics compute per-SKU velocity across every connected channel, which is the raw material for exactly this ranking.
How to actually improve it
- Reorder less, more often on proven movers, smaller purchase orders raise turns without risking availability, provided your reorder points are honest.
- Clear the tail deliberately: bundle, discount, or delist the bottom decile instead of letting it age with dignity.
- Match depth to velocity per channel: if a SKU earns its keep only on one marketplace, stop stocking for five.
- Watch seasonality windows: pre-season builds legitimately depress the ratio; the mistake is carrying the build past the season.
Common questions
Is a higher inventory turnover always better?
No. Past a point, high turnover means thin stock, and thin stock plus multichannel demand is the oversell and stockout zone. The goal is the highest ratio that never interrupts sales.
How often should I calculate it?
Quarterly for the business-level number, continuously for the per-SKU operational view, which is why it belongs on a dashboard rather than in a year-end spreadsheet.
Turnover ratio versus days of cover - which do I use?
Turnover for financial health, backward-looking, at cost. Days of cover for operations, forward-looking, in units per SKU. They answer different questions and disagree productively.
Does inventory turnover include unsold returns?
Returned-to-stock units belong in inventory value; refunded sales come out of COGS. Sloppy returns accounting quietly flatters the ratio.
See the per-SKU truth behind your ratio
Unifystock tracks sales across every channel you sell on, from $49/month with unlimited orders, with live per-SKU velocity, days-of-cover and stockout forecasts on the plans above. See pricing.