Amazon FBA Inventory Statistics That Actually Matter | Inventory Hero
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Amazon FBA Inventory Statistics That Actually Matter
The FBA inventory statistics that move your business are your own: turnover, sell-through, IPI, stockouts, returns. What each tells you and how to read it.
What inventory statistics should Amazon FBA sellers track?
The core set is inventory turnover (how fast stock sells), days of supply (how long current stock lasts), sell-through rate (share of available stock sold in a period), your IPI score (Amazon's inventory-health index), stockout rate (how often SKUs hit zero), and return rate. Track them per SKU and against your own trend, because these first-party numbers, not industry averages, are what actually move your business.
T. Brian Jones is co-founder and CTO of Inventory Hero. He leads the engineering behind its Amazon data pipeline, demand forecasting, and the AI platform that lets sellers talk to their live inventory, sales, and supplier data in plain language.
There is no single good number; it varies sharply by category, from many turns a year for fast consumables to just a few for slow, high-margin goods. Rather than chase an industry figure, compare your turnover to your own history and to similar products, and watch the trend. A turnover that is falling means stock is building faster than it sells, which is the signal that matters more than any benchmark.
Where do I find my FBA inventory statistics?
Most come from Seller Central: sales velocity from Business Reports, on-hand and aging from the FBA inventory and inventory-age reports, your IPI from the inventory dashboard, and returns from the FBA Customer Returns report. Combine those with your own cost data to compute turnover, days of supply, and margin. Inventory software can calculate and track these per SKU continuously so you are not rebuilding them by hand.
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The Amazon FBA inventory statistics that actually move your business are your own numbers, not industry averages: how fast your stock turns, how long it lasts, how much sells through, and how often it runs out or comes back. The short version: the core set is turnover, days of supply, sell-through, IPI, stockout rate, and return rate, and you read each against your own trend and category rather than a single benchmark. Below is what each statistic tells you and how to read it.
People search for FBA inventory statistics hoping for a benchmark to measure against. The honest answer is that broad industry figures, while interesting, rarely change a decision: healthy ranges vary so much by category, price point, and business model that a single average is close to meaningless for your specific SKU.
What does change decisions is your own data, tracked per SKU and over time. Is this product's turnover rising or falling? Is its sell-through healthy for its category? Is it heading for a stockout or aging into a fee? Those first-party statistics are what you act on, so they are what this guide focuses on.
A handful of numbers cover most of what you need to know:
Inventory turnover. How many times you sell through and replace stock in a period. Higher means capital is working harder; falling means stock is building.
Days of supply. How long current stock lasts at your recent pace, the forward-looking view that drives reorder timing.
Sell-through rate. The share of available stock sold in a period, a read on how well demand matches supply.
IPI score. Amazon's own inventory-health index, which influences your storage capacity.
Stockout rate. How often your SKUs hit zero, the direct measure of the most expensive routine mistake.
Return rate. Returns as a share of sales, which distorts true demand and ties up units.
Together these tell you whether your inventory is healthy, working, and heading for trouble, which is the whole job.
Cost and margin from your own landed-cost records.
Combining these by hand is doable but tedious per SKU, which is where inventory software earns its place, calculating and tracking the whole set continuously so you manage on live numbers rather than a monthly reconstruction.
You do not need a dashboard obsession; a short monthly pass over the core statistics catches most problems:
Scan turnover and days of supply per SKU for anything trending the wrong way, stock building or thinning faster than expected.
Check the aging profile for SKUs approaching the surcharge, and act on them before the fee.
Review stockouts and near-misses from the month, and adjust reorder points that fired late.
Read return rate on your highest-volume SKUs for any climbing number that signals a product or listing problem.
A quick worked read: sell-through rate is units sold divided by units available, so 200 sold against 50 still on hand is 200 / 250, or 80 percent, a healthy sign demand is keeping pace with stock.
Confirm your IPI is steady or improving, since it gates your storage capacity.
Fifteen minutes a month across these turns the statistics from numbers you have into decisions you make, which is the entire point of tracking them.
The Amazon FBA inventory statistics that matter are your own: turnover, days of supply, sell-through, IPI, stockout rate, and return rate on the operational side, and DIO, GMROI, and your aging profile on the cash side. Read each against your own trend and your category, per SKU, and pair related numbers for context, because an industry average cannot tell you what to do with a specific product. Track the set that changes your decisions. For the metric that anchors them, see inventory turnover; for the health index Amazon watches, the IPI score.