Storage is the fee that punishes optimism
Fulfillment fees charge you when a unit sells. Storage charges you while it doesn't — monthly, on the cubic volume your inventory occupies, at $0.78 per cubic foot for most of the year and $2.40 through Q4 for standard-size products. Then, from day 181, the aged-inventory surcharge starts and escalates with age: the units you bought for a launch that didn't happen quietly become the most expensive stock you own. One seller essay puts it plainly: buy 300 units that sell 40 a month and units 100–300 collect storage, aged surcharges and Q4 rates — "the product did not fail, the buying decision did." This estimator makes that slow bleed visible before the purchase order, per unit and per month.
Rates: standard size $0.78 (Jan–Sep) and $2.40 (Oct–Dec); oversize $0.56 and $1.40. Aged surcharge from day 181, reaching $6.90 per cu ft — or $0.15 per unit, whichever is greater — beyond a year. Removal or disposal, if it comes to that, runs roughly $0.84–$14.32 a unit by tier: sometimes the cheapest exit is paying to destroy stock, and this page's numbers tell you when.
Worked example
One hundred 10×8×6 in units are 27.8 cubic feet. Held from November for three months they cost $155.00 — $66.67 in each Q4 month against $21.67 in January — $1.55 of storage on every unit, before a single aged day. Let the average unit age past a year and the surcharge alone adds roughly $191.67 a month at that volume.
How to use this calculator
- Enter the packaged dimensions and the units you are thinking of sending in — the size of the decision, not the size of the first order.
- Set the start month honestly: inventory landing in September meets the Q4 rate almost immediately.
- Compare per-unit storage against your margin from the FBA Calculator — if storage eats a third of it, the order is too big.
- Watch the day-181 line: plan the exit (price cut, removal, promotion) before the surcharge plans it for you.