The weekly inventory review is a short job with one purpose: **find the ASINs whose runway has changed** before that change becomes a stockout.

It takes minutes when the data is in front of you, and it is the single highest-return recurring task in the business.

[Watch the walkthrough](https://kb.trackiq.com/kb-assets/kbvideo-invlevels-explainer-51d89615.mp4)

*Prefer to watch? One hundred and five seconds on why runway is a ratio rather than a number, the four figures worth reading, and the failure mode that is not looking at all.*

## **Think in days, not units**

Units in stock is not a useful number on its own. **Days of inventory** is, because it answers the only question that matters: how long until this runs out at the rate it is currently selling?

**Days of inventory = units available ÷ current daily sales velocity**

A product with 4,000 units looks healthy until you notice it sells 200 a day and the next shipment lands in 35 days.

![Stock and days of cover, per ASIN](/kb-assets/shot-inv-table-2e21b7.png)

## **What to look at**

Per child ASIN, four numbers:

**Available units** — sellable right now.

**Reserved units** — committed to orders or in transfer, and not available to sell. Counting these as stock is a common way to be surprised.

**Inbound units** — on their way to Amazon, with a date attached. Units without a credible arrival date are not cover.

**Sales velocity** — recent average daily units. Recent matters; a 90-day average hides a product that has doubled in the last fortnight.

Then the derived views: **days of inventory at Amazon**, **days including your warehouse or 3PL**, and **days across the whole pipeline**. They answer different questions — the first is when you stop selling, the last is whether you have a supply problem or a logistics problem.

## **Watch the velocity, not just the level**

**This is the part that gets missed.** The stock number can be unchanged week to week while your runway collapses, because runway is a ratio.

**Selling faster than planned** — planned for 50 a day, now doing 75 — and your cover has dropped by a third with no change to the stock figure. Good news that becomes a stockout if nobody notices.

**Selling slower than planned** — planned 50, doing 30 — and you are now carrying more stock than the product justifies. That is cash sitting still, plus storage fees, plus long-term storage surcharges if it drags.

**So compare this week's velocity to last week's, and to what you assumed when you ordered.** A change of 30% or more in either direction needs a decision.

## **The weekly routine**

**Do it at a fixed point in the week**, alongside your other numbers rather than as a separate task. It only works if it is habitual.

**1. Sort by days of inventory, ascending.** The problems are at the top.

**2. For anything under your lead time plus a buffer, act.** If replenishment takes 45 days and an ASIN has 40 days of cover, that is already a stockout unless something changes.

**3. Check velocity changes across the catalogue.** Look for anything that moved sharply, in either direction.

**4. Flag your top sellers separately regardless.** They deserve a look even when the numbers look fine, because the cost of being wrong is much higher.

**5. Note anything that came back into stock**, and push it back to normal sales deliberately — recovery is not automatic.

## **Acting on what you find**

**Heading for a stockout, with time to fix it** — expedite the next shipment, move units from your warehouse or 3PL, or place an emergency order.

**Heading for a stockout with no time** — slow sales down deliberately and take more margin per unit while it lasts. See [**When You Are Going Out of Stock**](https://kb.trackiq.com/hc/knowledge-base/articles/going-out-of-stock).

**Overstocked** — the levers are the reverse: promotions, coupons, deals, and more advertising spend. An overstocked product is a candidate for the advertising budget you were about to spend elsewhere.

**Velocity up sharply** — revise the forecast now, not at the next planning cycle. The purchase order you are about to place was sized on the old number.

## **Making it harder to skip**

The honest failure mode is not misreading the data, it is not looking during a busy week.

**Set alerts on the products that matter** — low days-of-cover on your top sellers, and sharp velocity changes anywhere. That turns the weekly review from the only line of defence into a second one. See [**Setting Up Smart Alerts**](https://kb.trackiq.com/hc/knowledge-base/articles/setting-up-smart-alerts-and-real-time-notifications) and [**Alert Categories Explained**](https://kb.trackiq.com/hc/knowledge-base/articles/alert-categories-explained).

**And keep it in one place.** The reason this task gets skipped is usually that assembling the view takes longer than reading it. See [**How to Monitor Your Stock Levels**](https://kb.trackiq.com/hc/knowledge-base/articles/how-to-monitor-your-stock-levels).

## **Common mistakes**

**Counting reserved units as available.**

**Counting inbound units with no confirmed arrival date.**

**Using a long velocity average** that hides a recent change.

**Reviewing monthly** on products whose lead time is measured in weeks.

**Treating overstock as harmless.** It is slower-moving money and a growing storage bill.

## **Related**

- [**Why Inventory Is the Second Pillar**](https://kb.trackiq.com/hc/knowledge-base/articles/why-inventory-is-the-second-pillar) — why this outranks other optimisation work.
- [**Inventory Forecasting and Purchase Orders**](https://kb.trackiq.com/hc/knowledge-base/articles/inventory-forecasting) — the planning half.
- [**Catch a Stockout Early**](https://kb.trackiq.com/hc/knowledge-base/articles/catch-a-stockout-early) — the same check on the TrackIQ screen.