Amazon Aged Inventory Surcharge Calculator

What the formula says

The aged inventory surcharge is charged per cubic foot per month on units that have been in a fulfilment centre beyond the age thresholds, in bands that escalate with age.

It sits on top of ordinary monthly storage rather than replacing it, so aged stock pays both.

Surcharge = aged cubic feet in each band × that band's monthly rate, summed across bands.

The numbers, worked through

1,200 units of the small standard product at 0.0625 cubic feet is 75 cubic feet. Ordinary storage on that is around $59 a month off-peak.

Once past 181 days the surcharge adds roughly $38 a month at the first band. Past 271 days the rate steps up materially, and past 365 days it becomes punitive, the combined charge on that 75 cubic feet can exceed $400 a month.

Against $10,200 of cost value in that stock, a year of holding at the top bands would consume a substantial fraction of what the goods are worth.

The escalation is designed so that no rational seller holds stock that long, and sellers who do are almost always avoiding a decision rather than making one.

What the number leaves out

The age clock starts at receipt into the fulfilment centre, and the assessment happens on a snapshot date each month. Units removed a day after the snapshot pay a full month they could have avoided.

Sellers also frequently assume that selling some units resets the position. It does not, Amazon ages inventory on a first-in basis, so the oldest units remain oldest regardless of sales volume.

Turning it into a decision

Set a calendar reminder at 120 days rather than reacting at 181. Every option available at four months is better than every option available at seven.

Then choose deliberately between price action, bundling, removal and disposal, comparing each against the surcharge it avoids. Disposal at $0.32 a unit to avoid a year of escalating charges is frequently the highest-return decision available.

Preventing it rather than clearing it

Aged inventory is nearly always created at the purchase order, not in the warehouse. An order sized on an optimistic forecast, a minimum order quantity accepted without challenge, or a seasonal product bought late all produce it.

The control that works is a cover ceiling on inbound shipments, no shipment that would take FBA cover past a stated number of weeks without a written reason. Amazon's restock limits impose a version of this externally, and sellers who resent them are usually the ones who most needed them.

The second control is sending stock in tranches. Holding reserve inventory at a third-party warehouse and replenishing FBA against demand costs a little in handling and removes the aging risk entirely, which for a seasonal or unproven product is a good trade.

One further mechanism worth knowing: Amazon periodically offers reduced or waived removal fees during promotional windows, which can make a removal decision materially cheaper if it can wait a few weeks.

That is worth checking before paying full removal rates on a large quantity, provided the aging bands are not about to escalate in the meantime.