Amazon FBA Storage: What It Costs and Why the Bill Changes Every Month

How Amazon FBA storage fees work

Amazon charges an FBA storage fee every month based on how much physical space your inventory takes up in a fulfillment center, not on what the inventory is worth. Amazon measures your average daily volume in cubic feet across the month, then applies a rate that depends on your size tier — standard-size versus oversize — and the season. The rate runs higher from October through December, because that's when fulfillment centers are tightest and Amazon prices the shelf space accordingly.

That base storage fee is only the starting point. Amazon layers other charges on top depending on how long inventory sits and what happens if it doesn't sell: an aged inventory surcharge, removal or disposal fees if you pull it out, and a liquidation fee if Amazon sells it off for you. Amazon's own Revenue Calculator will estimate the base fee for a specific ASIN, but it won't tell you what happens if that ASIN is still sitting there in month six — that's the part sellers usually get wrong.

A worked example: what storage costs before you sell a unit

Here's the mechanic, worked through with round numbers so the math is visible. Check Seller Central for the exact rate that applies to your size tier and month — Amazon updates these periodically, and a number quoted elsewhere may already be out of date.

Say a slim standard-size item — a wallet, the kind of category a brand like Ridge sells in — takes up 0.3 cubic feet per unit. Store 3,000 units for three months before they sell through, and you're carrying 900 cubic-feet-months of space. Multiply that by whatever the published monthly rate is for standard-size items that quarter, and that's the storage bill before a single sale happens. Now take a bulky item — a stockpot, the category HexClad sells in — at roughly 2 cubic feet per unit. The same 3,000 units cost several times as much to store, purely because the fee is volume-based, not value-based. A slow-moving oversize SKU can quietly cost more to store than it earns in margin, and nobody notices until the aged inventory surcharge lands on top.

The aged inventory surcharge is a second, separate fee

The aged inventory surcharge stacks on top of the storage fee, it doesn't replace it. Amazon breaks it into aging bands — units sitting 181 to 270 days, 271 to 365 days, and over 365 days each get charged at a steeper rate than the last. A unit that's been sitting since day 200 is paying the regular monthly storage fee and the surcharge, every month it stays.

Using the pot example above: if those oversize units don't sell within six months, they cross into aged inventory territory and the bill for that SKU jumps again, on top of the already more expensive size tier. This is exactly where the removal-versus-liquidation decision matters — past a certain point, paying Amazon to remove or liquidate the stock is cheaper than paying to keep storing it while it ages further.

The mistake most sellers make (we've made it too)

The common mistake is treating the storage fee as a fixed cost of doing business instead of a signal. A rising storage bill on one SKU almost always means the reorder timing was wrong — too much stock landed too early, or a promotion that was supposed to move it fell through. Across more than $500M in managed revenue and 100+ brands, we've watched the same pattern: the storage fee itself is rarely the real problem. It's the symptom that shows up 60 to 90 days after a purchasing decision nobody revisited.

A mistake we've made ourselves: reacting to the storage fee line item in isolation instead of checking whether the SKU was already past 181 days when the surcharge posted. Fixing the size tier or the reorder quantity going forward does nothing for units already aged — those need a removal or liquidation call now, not a note for next quarter's planning.

When the number looks wrong, or the fix didn't work

If the fee looks wrong, start with the size tier. Amazon calculates cubic feet from the dimensions on file, and a dimension entered in the wrong unit, or a product that got reclassified from standard to oversize after a packaging change, will inflate the fee without anything about the physical product changing. Check the dimensions Amazon has on record against what you actually shipped before assuming the rate is the problem.

If you already pulled a slow-moving SKU — removal or liquidation — but the aged inventory surcharge still shows up the following month, check the timing. Amazon bills storage fees on inventory present as of a snapshot date each month; if the removal order was filed after that date, the SKU gets charged one more cycle. That's not an error to dispute, it's a calendar problem, and it's worth building removal timing around the snapshot date rather than around whenever you happened to notice the SKU was stale.

Where this fits with the rest of your FBA costs

None of this requires a new system for a small catalog — a spreadsheet and a monthly Seller Central check will catch most of it. Where it gets hard is at scale, across hundreds of SKUs, where the reorder decision, the 181-day clock, and the removal-versus-liquidation math need to happen for every SKU, every month, not just the ones someone notices. Dr. Stock, from Full Circle, works that specific set of leaks — reorder timing, aged inventory and the removal call, alongside FBA fee errors and reimbursement recovery — with inventory purchasing decisions always going to a human, whatever autonomy level a client sets. If the leak you're actually chasing is in the ad account, not the warehouse, that's a Dr. PPC problem, not a storage one.