Stock coverage

Stock coverage is units on hand divided by units sold per day: how many days the stock you hold will last at the current pace. It converts a stock level into the only unit that matters for reordering, which is time, and it is read against the supplier's lead time.

The comparison that makes it actionable is against lead time. Forty units selling at 2,5 a day is sixteen days of coverage; if the supplier needs three weeks, the reorder is already late, and no amount of staring at the stock level itself would have said so. The division is deliberately naive, and that is its virtue: no forecast and no model, just the shelf against the clock, which makes it the one inventory number everyone reads the same way.

The velocity in the denominator is a choice, and it decides what the number means. A seven-day window reacts fast and panics at every spike; a thirty-day window is calm and misses a trend for weeks. Whichever window is chosen, it has to be the same one across the catalogue, or coverage stops being comparable between products.

Seasonality distorts it in both directions: coverage computed on August velocity overstates how long stock lasts into a September push, and December velocity makes January stock look like years. Around promotions, read it on the pace you expect rather than the pace you just had.

At zero velocity it is undefined rather than infinite, and should be shown as unknown. A product that has not sold in thirty days does not have infinite coverage, it has a different problem, and printing a dash instead of a number is the honest way to say so.

Read it beside inventory value at cost: high coverage on a cheap accessory is untidy, high coverage on an expensive line is where working capital goes to sleep. The pair is exactly what the Inventory report puts on one row per SKU.