Lesson 8 of 10
Stock is money standing still
Every unit sitting in FBA is cash you already spent and can't spend again until it sells, so how long it sits matters as much as whether it sells at all.
Lesson 3 put a number on landed cost: what a unit cost to acquire, ship and land before it ever reached a shelf. That cash left Marleigh & Rowe the moment it was paid — not when the unit finally sold. Every one of this window’s trading rows already carries that cost, because every one of them sold. The same is true of every unit still sitting unsold in an Amazon warehouse right now: the cash for it is already spent, and it cannot be spent again until that unit sells. Stock is not an asset sitting still. It is cash sitting still.
This snapshot stops there. It is built from orders that happened, not from Amazon’s own inventory report, so it carries no figure for what is sitting unsold right now. That figure — and the three ideas below — live on the Inventory page.
Days of cover: how long the cash stays tied up
Days of cover is how long the stock on hand will last at the rate it is actually selling — sellable units divided by a daily sales rate. The Inventory page shows two versions of it side by side on the same row, because they are not always the same measurement: this app’s own figure, built from exactly the stock it can see is sellable today, and Amazon’s own days-of-supply figure from its replenishment report, which answers for a wider region rather than one marketplace. A gap between the two usually means they are counting different pools of stock, not that either one is wrong.
Sell-through: the rate cover is measured against
Cover is only as good as the sales rate it is divided by, and that rate — velocity, on the Inventory page — is itself worth watching on its own: units per day, gathered across every channel drawing on the same physical stock, averaged over a trailing window rather than a single day’s noise. A slowing velocity means the same units on the shelf now cover more days than they did last week, which is the cash staying tied up for longer, not less stock to worry about.
Restock: turning cover into an action
Amazon recommends what to send and where, and the Inventory page prices that recommendation at this account’s own landed unit cost — the same figure lesson 3 built, applied forward instead of back. Where a SKU has no landed cost on file in Settings, the page shows “no cost” rather than a dollar figure, for the same reason Contribution (lesson 4) gives a row with a missing cost no verdict rather than a guess: pricing hundreds of recommended units at nothing would understate a budget someone is about to commit real cash against.
Why stock belongs beside profit, not after it
A product can clear the bar on every sale it makes and still be starving the business of cash, if what it takes to keep it in stock outpaces what it earns back. Margin answers “is each sale worth making.” Cover and velocity answer a different question the margin alone never will: how long the cash stays locked up before that sale even happens again.