Inventory turns is how many times in a year you sell through your average stock holding.
Days inventory outstanding is the same number expressed as time — how long the average item sits before it is sold. Four turns a year is about ninety days on the shelf.
Why turns matter more than value
Stock is cash you have already spent and cannot use. Every item on a shelf was paid for with money that is no longer available for wages, materials or a slow month.
Turns measure how quickly that money comes back. A business holding the same value of stock at six turns has its cash working three times harder than one at two turns.
What good looks like
Roughly four to eight turns a year for retail, two to four for wholesale. Service trades holding parts vary too widely for a benchmark to be meaningful — compare against your own trend instead.
The direction matters more than the level. Turns falling while revenue holds steady means stock is accumulating faster than it is selling, and the cash tied up is growing.
Both extremes cost money
Too slow — cash trapped in stock, and rising exposure to items that stop selling. See dead stock.
Too fast — you are running thin, which shows up as jobs needing a second visit because the part was not on the van. That is a real cost too, and it lands as multi-visit jobs rather than as an inventory number.
The right level is the one that keeps first-visit completion high without parking cash on a shelf, and it is found per part rather than across the whole holding.
Available where inventory tracking is enabled for your workspace.