Amazon FBA storage fees can turn a profitable product into slow-moving, expensive inventory. The charge is not based only on the number of units in a fulfilment centre. Amazon uses the average daily space your inventory occupies, the product size category, the month of the year, dangerous-goods status and how long stock has remained in storage.
This guide shows how to estimate monthly storage, understand peak-season increases and spot aged inventory before the surcharge grows. Use the free Amazon FBA Storage Fee Calculator to test your own dimensions, unit count, storage period and editable rates.
What Amazon FBA storage fees cover
Fulfilment by Amazon stores seller inventory in Amazon’s fulfilment network, then picks, packs and ships orders. Storage is only one part of the FBA cost structure.
The main inventory-related charges can include:
- Monthly inventory storage: charged for the space inventory occupies.
- Aged inventory surcharge: an additional monthly charge on units stored for 181 days or longer.
- Storage-utilisation or capacity-related charges: may apply when inventory uses space inefficiently under Amazon’s current rules.
- Removal, disposal or liquidation fees: charged when stock is taken out of the fulfilment network through those services.
FBA fulfilment fees, referral fees, inbound transportation and advertising are separate. For a broader product-profit check, use the Amazon FBA Profit Calculator and read the guide to Amazon FBA fees and profitability.
How Amazon calculates monthly inventory storage
Amazon says monthly storage costs depend on product size, volume, the average number of daily units stored, dangerous-goods status and the month of the year.
A useful estimate is:
Monthly storage fee = Average cubic feet stored × Monthly rate per cubic foot
To estimate cubic feet for a rectangular packaged unit:
Unit cubic feet = Length × Width × Height in inches ÷ 1,728
Then:
Average cubic feet stored = Unit cubic feet × Average daily units
Use the packaged dimensions Amazon records, not only the bare product dimensions. A small difference in packaging across hundreds of units can materially change storage volume and may affect the product’s size tier.
Amazon FBA storage fee example
Assume one packaged unit measures 12 × 8 × 4 inches and the average daily inventory is 300 units.
- Unit volume: 12 × 8 × 4 = 384 cubic inches
- Unit cubic feet: 384 ÷ 1,728 = 0.2222 cubic feet
- Average volume: 0.2222 × 300 = 66.67 cubic feet
Amazon’s US supply-chain page currently displays standard-size FBA storage examples of $0.78 per cubic foot per month from January through September and $2.40 from October through December.
- January–September estimate: 66.67 × $0.78 = about $52 per month
- October–December estimate: 66.67 × $2.40 = about $160 per month
The same inventory footprint costs roughly $108 more per month during the displayed peak-season period. This example excludes aged-inventory, storage-utilisation and other possible charges. Rates vary by marketplace, size category, programme and current fee schedule, so verify the figures in Seller Central before ordering stock.
Why October to December can change product profit
Amazon’s displayed standard-size US storage rate is much higher during October, November and December. Those months cover the holiday selling season, when fulfilment-centre space is under greater pressure.
A seller who orders deeply for holiday demand faces two opposite risks:
- Too little inventory can cause stockouts and lost ranking or sales.
- Too much inventory can remain after the season, incur peak storage and age into later surcharges.
Forecast at SKU level rather than using one shop-wide growth percentage. Separate dependable sellers, seasonal products, new launches and slow stock. The safety stock formula can help protect availability without turning every forecast error into months of excess inventory.
What is the Amazon aged inventory surcharge?
Amazon states that the aged inventory surcharge applies monthly to items stored in a fulfilment centre for 181 days or longer. It is added to ordinary monthly storage rather than replacing it.
This means an old unit can create several costs at once:
- Normal monthly storage
- Aged-inventory surcharge
- Capital tied up in unsold stock
- Possible discount, removal or disposal cost
- Opportunity cost from using inventory capacity
The surcharge generally becomes more severe as inventory moves into older age bands. Exact bands and rates change, so use Amazon’s current aged-inventory report and fee schedule rather than copying an old table from a blog or spreadsheet.
Storage cost per unit
Dividing the total monthly storage fee by average units gives a simple monthly cost per unit:
Monthly storage per unit = Total monthly storage fee ÷ Average daily units
In the earlier example:
- January–September: $52 ÷ 300 = about $0.17 per unit per month
- October–December: $160 ÷ 300 = about $0.53 per unit per month
A unit held for six months does not cost only one month of storage. Approximate holding cost by summing each month’s storage, including any seasonal rate change and aged surcharge.
When comparing products, calculate storage as a percentage of selling price and contribution margin. A bulky $20 product can lose profit much faster than a compact $80 product.
Why average inventory matters more than month-end stock
Amazon bases monthly storage on average daily volume. Looking only at the last day of the month can hide the real exposure.
For example, receiving 1,000 units on the first day and selling 700 gradually still uses substantial space throughout the month, even if only 300 remain at month-end. A useful forecast should model daily or weekly inventory movement rather than multiplying the closing balance by a rate.
If you do not have detailed data, use the average of expected opening and closing units as a rough planning estimate:
Estimated average units = (Opening units + Closing units) ÷ 2
This shortcut assumes sales occur reasonably evenly. It will be inaccurate for sudden deliveries, promotions or seasonal spikes.
How storage fees affect reorder decisions
A reorder point answers when to order, but not always how much to order. Buying a large quantity may lower the supplier’s unit price while increasing:
- FBA storage
- Aged-inventory risk
- Cash tied up in stock
- Markdown exposure
- Removal or disposal costs
Compare the supplier discount with the full holding cost. Saving $0.30 per unit is not a saving if extra storage, financing and clearance discount total $1.10 per unit.
Use the Inventory Reorder Point Calculator for timing, then set an order quantity based on forecast demand, lead time, case packs, cash flow and storage exposure.
Find slow FBA stock before it becomes aged stock
Three measures are especially useful:
Sell-through rate
Sell-through shows how much available stock sold during a period. Compare it by SKU rather than relying on a blended store average. The guide to ecommerce sell-through rate explains the formula and how to diagnose slow items.
Inventory turnover
Turnover compares cost of goods sold with average inventory value. A falling turnover ratio can reveal that purchasing is growing faster than sales. Use the inventory turnover guide to translate the ratio into days of stock.
Weeks of cover
Weeks of cover estimates how long current inventory will last at the recent sales rate:
Weeks of cover = Units on hand ÷ Average weekly unit sales
If a SKU has 600 units and sells 30 per week, it holds about 20 weeks of cover before considering inbound units. Compare that with lead time, seasonality and the 181-day aged-inventory threshold.
Seven ways to reduce FBA storage costs
1. Send smaller, more frequent replenishments
Hold enough Prime-ready stock for expected demand and keep reserve stock elsewhere when the economics work. This reduces average FBA volume but may increase inbound freight, so compare both costs.
2. Fix oversized packaging
Reduce empty space while protecting the product. Re-measure the final packaged unit and check whether a packaging change affects the recorded size tier.
3. Stop automatic reordering of slow SKUs
A global reorder rule can keep feeding inventory into listings that no longer sell. Require a minimum recent sales rate before creating a purchase order.
4. Run promotions before the age threshold
A controlled discount before stock becomes aged may cost less than months of storage plus a later clearance. Use the Discount & Sale Price Calculator to protect contribution margin.
5. Remove or liquidate stock using total-cost math
Compare future storage and expected selling profit with removal, disposal, liquidation and return-to-supplier options. Do not keep stock only because money has already been spent on it.
6. Separate seasonal and evergreen forecasts
Holiday stock should have an exit plan before the season. Evergreen stock can support steadier replenishment, while seasonal units need earlier markdown and removal dates.
7. Review the inventory age report every month
Group units by age band, estimate future fees and assign an action owner. Waiting until the surcharge appears removes valuable options.
Monthly FBA storage review checklist
- Download the current inventory and fee reports from Seller Central.
- Confirm Amazon’s packaged dimensions for high-volume SKUs.
- Calculate average cubic feet and storage cost per unit.
- Separate January–September and October–December assumptions.
- Review units approaching 181 days.
- Compare weeks of cover with lead time and forecast sales.
- Pause or reduce replenishment for slow SKUs.
- Choose promotion, removal or liquidation actions before fees compound.
- Update product contribution margins with actual storage costs.
Frequently asked questions
How are Amazon FBA storage fees calculated?
Amazon bases monthly storage on the average daily volume inventory occupies in fulfilment centres. Product size, volume, dangerous-goods status, the month and marketplace affect the rate.
When do Amazon aged inventory fees start?
Amazon currently states that the monthly aged inventory surcharge applies to units stored for 181 days or longer. Check Seller Central for the current age bands and rates.
Why are FBA storage fees higher in Q4?
Amazon charges higher displayed standard-size US storage rates from October through December, when fulfilment-centre space is in stronger seasonal demand.
Does FBA storage include fulfilment fees?
No. Monthly storage is separate from the per-unit fulfilment charge, referral fee, selling plan, inbound shipping, advertising and possible surcharges.
Can the calculator match my exact Amazon invoice?
It provides an estimate from the dimensions, unit count, storage duration and rates entered. Exact billing depends on Amazon’s recorded dimensions, average daily inventory, marketplace, programme, product status and current fee schedule.
Estimate the cost now with the Amazon FBA Storage Fee Calculator, then compare the result with Seller Central’s fee preview and inventory reports.
Sources checked 29 September 2026: Amazon’s selling fee overview, Amazon FBA cost guidance, Amazon’s current storage-rate comparison, and Amazon fee-estimation guidance.