Amazon IPI Score: What It Is, What Moves It, and What to Do When It Drops

What the IPI score actually is

IPI stands for Inventory Performance Index. It's a single number from 0 to 1000 that Amazon calculates for every FBA seller, based on how well you're managing what's sitting in their warehouses. You find it in Seller Central under Inventory Planning, on the Inventory Performance dashboard.

Amazon has never published the exact formula. What it has published is that four things feed into it: excess inventory, sell-through rate, stranded inventory, and in-stock rate. It recalculates roughly weekly, usually landing on Sundays, so a fix you make on Monday won't show up in the number until the following week at the earliest.

Amazon has also moved the goalposts on what counts as an acceptable score more than once. The threshold for avoiding storage limits was raised from 350 to 400, then to 500, then dropped back to 450 during 2020's capacity crunch. That history matters for one reason: if you're reading a number off an old blog post or forum thread, treat it as expired. Your account's current threshold, if one applies, is shown on your own dashboard. That's the only number that counts.

The four inputs that build your score

Amazon weights these four factors, but it doesn't say how much each one counts. What it does tell you is what each one measures and roughly which direction to push it.

A worked example: how the math actually moves

Say you're carrying a SKU with 90 days of supply on hand and a sell-through rate low enough that Amazon's algorithm flags a chunk of it as excess. That excess percentage, not the raw unit count, is what hits your score. Cut days of supply on that SKU to something closer to 45, either by slowing incoming POs or running it down through normal sales, and the excess percentage on that SKU drops out of the calculation without you touching the other three factors at all.

The mistake sellers make here is trying to fix excess by shipping in less inventory across the board, which then starves fast-movers and tanks the in-stock rate factor instead. You've traded one problem for another. The fix has to be SKU-by-SKU: identify which specific ASINs are carrying the excess weight, and act on those, not on total inventory dollars.

Across the more than $500M in managed revenue Full Circle has managed for 100+ brands, this is the single most common IPI drag we see: not one catastrophic SKU, but three or four slow movers quietly dragging the whole account's excess percentage up while the seller is watching the wrong number.

When the score itself is the problem

Sometimes the number is bad news and the fix you tried doesn't move it. A few things to check before you assume the score is wrong:

• Give it time. The score updates weekly. A fix made this week won't register until next week's calculation, sometimes the one after.
• Check for stranded listings you don't know about. A deactivated listing, a suppressed buy box, or a units-in-an-unfulfillable-state issue can sit in stranded inventory without showing up anywhere obvious in your day-to-day view.
• Don't confuse IPI with the Account Health Rating. They're different scores, on different dashboards, driven by different inputs. Fixing one does nothing for the other.
• Restock limits and storage limits don't always move in lockstep with the score anymore. Amazon has changed how it ties capacity to IPI more than once. Read the specific banner or notice on your account rather than assuming the old score-to-limit mapping still applies.

Mistakes that tank the score, including ones we've made

The most common self-inflicted wound is a blanket removal order run on a slow SKU without checking whether the slowness is seasonal or permanent. We've made this call ourselves on a client's inventory before checking seasonality closely enough, and the removal lockout period that follows a removal order then blocked a restock right as demand came back. The score improved for a few weeks. The stockout that followed cost more than the excess-inventory penalty ever did.

Other patterns worth watching for: treating IPI as a vanity number with no real consequence until a storage limit notice arrives; over-correcting in-stock rate by over-ordering, which just creates next quarter's excess problem; and ignoring stranded inventory because the unit count looks small, when it's the percentage, not the count, that Amazon is scoring.

If the sell-through side of the problem traces back to paused or cut ad spend rather than anything happening in the warehouse, that's a Dr. PPC problem, not an inventory one — fixing reorder timing won't help a SKU that stopped getting traffic.