Days Inventory Outstanding (DIO)

Days inventory outstanding measures how long a dollar sits on the shelf. It divides average inventory by cost of goods sold and scales to days: a DIO of 60 means the company holds about two months of sales in stock. Together with days sales outstanding (collections) and days payable outstanding (supplier terms), it forms the cash conversion cycle — the number of days the company's cash is tied up funding operations.

For credit analysis of distributors, retailers, and manufacturers, rising DIO is one of the most reliable early warnings. Inventory that grows faster than sales means product is not moving: demand softened, buying was over-optimistic, or stock is aging into obsolescence. Because inventory is usually the largest current asset backing the current ratio, a liquidity picture that looks stable while DIO climbs is actually deteriorating — the "assets" are getting harder to convert to the cash that pays your invoices.

Benchmark within the industry: fast-moving consumer distribution might run 30-45 days, building materials 60-90, specialty equipment well over 100. And watch the year-end effect — companies manage inventory down for statement dates, so a quarterly view catches what an annual snapshot smooths over. When DIO jumps, ask the customer directly about aging and obsolescence reserves; the quality of the answer is itself diagnostic.