Inventory sitting on a shelf is cash a business can’t use for anything else — turnover measures how quickly that cash is actually cycling back through the business.
How it works
Cost of goods sold divided by average inventory gives the number of times inventory turns over in a year; dividing 365 by that figure gives the average number of days a unit sits before selling.
Why “average” inventory, not a single snapshot
Inventory levels can swing substantially within a year, especially for seasonal businesses — averaging the beginning and ending balance smooths that out rather than relying on whichever point happened to be measured.
How to use this calculator
- Enter annual cost of goods sold and average inventory.
A worked example
Cost of goods sold $600,000, average inventory $100,000: turnover = 600,000 ÷ 100,000 = 6, meaning inventory turned over about 60.83 days to sell (365 ÷ 6).
COGS $500,000, average inventory $125,000: turnover = 4, or 91.25 days to sell.
What the variables mean
| Variable | Meaning |
|---|---|
| COGS | Cost of goods sold over the period |
| Average inventory | Typical inventory value held during that period |
Edge cases worth knowing
A higher turnover number means inventory moves faster — but an unusually high figure can also signal understocking and lost sales, not just efficiency.
Zero average inventory makes turnover undefined — there’s nothing to divide the cost of goods sold by.
Frequently asked questions
Is a higher turnover always better?
Usually, but extremely high turnover can also mean running too lean and risking stockouts — the right level depends on the type of business.
Does this apply to service businesses without physical inventory?
No — inventory turnover is specific to businesses that hold physical goods for resale.
