Amazon FBA storage fees are charged monthly on the cubic-foot volume your inventory occupies, at a rate that depends on size tier (standard or oversize) and time of year, with Q4 rates running roughly double the rest of the year. On top of that sits an aged-inventory surcharge on stock that sits too long.
One correction before the math, because it costs sellers real money: the surcharge does not begin at 365 days. Amazon’s aged-inventory surcharge in the US starts at 181 days and escalates in bands as inventory ages further. Plenty of guidance still repeats the old 365-day rule, including the previous version of this article, and sellers planning around it get billed six months earlier than they expect.
We manage inventory economics for client accounts. We tested these levers across many catalogs, and in our experience two of them account for nearly all the savings. Below is the calculation, the current structure, and what genuinely reduces the bill.
How to calculate Amazon FBA storage fees monthly
Storage fee = volume in cubic feet × rate per cubic foot
Volume means the space your packaged units occupy. Not their weight. That trips people up.
Worked example
Say you hold 100 units, each measuring 12 x 10 x 6 inches.
- Volume of one unit: 12 × 10 × 6 = 720 cubic inches
- Convert to cubic feet: 720 ÷ 1,728 = 0.4167 cubic feet per unit
- Total volume: 0.4167 × 100 = 41.67 cubic feet
- Apply the rate. At an illustrative off-peak standard-size rate of $0.87 per cubic foot: 41.67 × 0.87 = about $36 per month
Now apply a Q4 rate, which historically runs to roughly $2.40 per cubic foot for standard size: 41.67 × 2.40 = about $100 per month for the same inventory.
That seasonal swing is the whole point. Holding identical stock from October through December costs materially more than holding it in spring, which is why I’d treat Q4 inventory planning as a profitability decision rather than a warehouse chore.
Treat every rate in this article as illustrative. Amazon revises its fee schedule at least annually and has added several surcharges in recent years, so pull current figures from the FBA fee schedule in Seller Central before modeling anything.
The aged-inventory surcharge
Here is where the real damage happens, and where that outdated 365-day figure misleads worst.
Amazon applies an aged-inventory surcharge in escalating bands beginning at 181 days in storage, with the charge rising as inventory ages through further thresholds, and the heaviest rates applying to stock past a year. It lands alongside your regular monthly charge, not instead of it. Both bills arrive.
The practical consequence: inventory that will not sell within roughly six months needs a decision, not patience. By the time a slow mover reaches its first birthday in a fulfillment center, the accumulated surcharges have often exceeded whatever margin the units carried.
Check the Inventory Age report monthly, which we cover among the reports worth reading in our Seller Central reports guide. It shows exactly which units are approaching a threshold, and it is the single most profitable report most sellers never open.
Other fees that stack on top
Storage is one line among several. Modeling it alone produces a flattering picture, and I’d never quote a margin from it:
- Fulfillment fees, per unit by size and weight, covering pick, pack, and delivery. Our pick and pack fee guide breaks that down and compares it against third-party fulfillment.
- Referral fees, typically 8% to 15% of sale price by category.
- Low-inventory-level fees, charged on products with persistently thin stock relative to demand, which effectively penalizes under-stocking as well as over-stocking.
- Storage utilization surcharges, applied where your stored volume is high relative to your sales rate.
- Removal or disposal fees, when you take aging stock out.
Notice the pincer in that list: Amazon now charges for holding too much and for holding too little. No cost-free extreme exists. That makes forecasting accuracy the genuine lever, rather than caution in either direction.
A worked comparison, since this decides real money
Two sellers, identical product, identical annual volume of 1,200 units. Each unit occupies 0.4 cubic feet.
Seller A ships 600 units at a time, twice a year. Average FBA holding is roughly 300 units, or 120 cubic feet. Across a year at mixed rates, storage runs into the high hundreds of dollars, and a portion of every shipment crosses the 181-day threshold and picks up aged-inventory surcharges.
Seller B ships 200 units at a time, six times a year, holding roughly 100 units on average, or 40 cubic feet. Storage costs roughly a third of Seller A’s, and almost nothing ever ages past six months. Seller B pays more in inbound freight and spends more hours on shipment creation.
Neither is universally right. Seller A buys convenience and freight economy; Seller B buys lower storage and near-zero aged risk. What matters is that both should have run the arithmetic, and in my experience only one of them ever does.
What drives your Amazon FBA storage fees up
Product dimensions above all. Volume is the multiplier, so packaging efficiency converts straight into savings. Trimming an inch off a box’s longest side can shift an item between size tiers, and I’ve watched that single change halve a storage bill.
Season. Peak rates roughly double. Plan inbound timing around that, deliberately.
Sell-through rate. Fast movers barely accrue anything. Slow movers accrue relentlessly, month after month.
Size tier. Oversize rates exceed standard by a wide margin. Design your packaging around those boundaries rather than discovering them after production.
Reducing the bill
- Shrink the packaging. The most powerful change available to you, and it cuts fulfillment charges too. Settle it with your supplier before production rather than afterward.
- Send less, more often. Deep FBA stock is expensive stock. Hold reserve inventory upstream instead, either at a prep center or in Amazon’s own AWD program, which exists precisely because FBA storage is costly at depth.
- Act on aged inventory before 181 days, not after. Discount it, bundle it, run it through ads, liquidate it. A unit sold at breakeven beats a unit accruing surcharges toward a disposal fee.
- Watch the Q4 calendar. Inbound your holiday stock late enough to avoid two months of peak-rate storage, early enough to survive receiving delays. That window is narrower than most sellers plan for.
- Forecast rather than guess. Thin-stock charges punish under-stocking too, so the win is accuracy. Not minimalism.
- Audit the whole unit economic. Model landed cost, referral, fulfillment, storage, returns, and advertising together. Skip that and you will price goods that look profitable and are not. I see it constantly.
If inventory economics is where your margin keeps disappearing, an account audit models the full picture per ASIN, and there is often reimbursable money sitting in storage and fulfillment discrepancies too, which is what our reimbursement service recovers.
FAQ
How are Amazon FBA storage fees calculated?
By volume: your inventory’s total cubic feet multiplied by the applicable rate per cubic foot, which varies by size tier (standard or oversize) and by season, with Q4 rates roughly double off-peak rates. Weight does not affect storage fees, only fulfillment fees.
When does Amazon’s long-term storage fee start?
The aged-inventory surcharge begins at 181 days in the US and escalates in bands as stock ages, with the highest rates on inventory past a year. Guidance still citing 365 days is out of date and will cost you six months of unexpected charges.
How much are Amazon FBA storage fees per cubic foot?
Rates change at least annually and differ by size tier and season, with Q4 running roughly double off-peak. Because published figures date quickly, take the current numbers from the FBA fee schedule in Seller Central rather than from any article.
Why are my FBA storage fees so high?
Usually one of four causes: oversized packaging inflating cubic volume, slow sell-through letting stock accumulate age, holding inventory through Q4 peak rates, or aged-inventory surcharges that began at 181 days without your noticing.
How do I reduce Amazon storage fees?
Reduce packaging volume, hold less depth in FBA while keeping reserve stock upstream (a prep center or AWD), clear aged inventory before it crosses 181 days, and time Q4 inbound carefully. Improve forecasting rather than simply stocking less, since low-inventory fees penalize thin stock too.
Does Amazon charge for having too little inventory?
Yes. Low-inventory-level fees apply to products with persistently thin stock relative to their demand, so both over-stocking and under-stocking carry costs. Forecast accuracy, not caution, is what actually reduces total fees.
Last updated: August 27, 2026. Amazon revises FBA fee schedules and surcharge thresholds at least annually; the fee schedule in Seller Central is the authoritative current source.
