What is the per-unit storage fee?
The per-unit storage fee is the monthly charge Amazon assesses on every unit stored in its FBA fulfillment centers, based on the cubic footage each unit occupies. Unlike the aged inventory surcharge, which only applies after 180 days, the monthly storage fee applies to all inventory from the day it arrives.
Amazon charges storage on the 15th of each month based on your average daily inventory volume. The rate depends on two factors: the product’s size tier (standard or oversize) and the time of year. Q4 rates (October through December) are roughly three times higher than the rest of the year because warehouse capacity is constrained by holiday inventory.
Most sellers underestimate storage costs because the per-unit amount looks small. But storage compounds across the catalog and across time. A product with 500 units averaging 60 days in the warehouse generates a very different storage bill than the same product turning in 20 days.
2026 storage rate card
| Size tier | Jan–Sep | Oct–Dec (Q4) | Per 0.139 cu ft unit (off-peak) |
|---|---|---|---|
| Standard-size | $0.78 / cu ft | $2.40 / cu ft | $0.11 / mo |
| Oversize | $0.56 / cu ft | $1.40 / cu ft | $0.08 / mo |
The Q4 multiplier is 3.1× for standard-size ($2.40 vs $0.78) and 2.5× for oversize ($1.40 vs $0.56). A product that costs $0.11 per month in storage from January through September costs $0.33 per month in Q4.
Example: annual storage cost on a mid-velocity SKU
Product: standard-size, 0.15 cu ft per unit (8 × 6 × 5 inches). Sells 100 units per month. Average on-hand: 150 units (6 weeks of supply). Total volume: 22.5 cu ft.
| Period | Rate | Monthly cost |
|---|---|---|
| Jan–Sep (9 months) | 22.5 cu ft × $0.78 | $17.55 / mo × 9 = $157.95 |
| Oct–Dec (3 months, Q4) | 22.5 cu ft × $2.40 | $54.00 / mo × 3 = $162.00 |
| Annual storage cost | $319.95 | |
| Per unit sold (1,200/year) | $0.27 |
At $0.27 per unit sold, storage consumes less than 1% of a $34 selling price. But change the velocity to 50 units per month (same 150 on hand) and the per-unit cost doubles to $0.53 because fewer units share the same storage bill. Slow movers pay a hidden premium in storage per unit.
The Q4 storage trap
Q4 rates triple precisely when sellers want maximum inventory for holiday sales. The instinct is to send everything in September to avoid stockouts during the holiday rush. But sending six months of inventory before October means paying $2.40 per cubic foot on units that will not sell until December or January.
The alternative: stage excess inventory in AWD ($0.56 per cubic foot, no Q4 increase) or a third-party warehouse, then drip-feed to FBA weekly as units sell. This keeps your FBA on-hand at 3-4 weeks of supply, minimizing the Q4 premium while maintaining in-stock rates. The tradeoff is a more complex replenishment workflow and slightly higher stockout risk during demand spikes.
Common mistakes
- Ignoring the Q4 rate jump when planning holiday inventory sends. Sending 3 months of supply in September instead of 6 weeks saves 50% on Q4 storage. Replenish weekly from a staging location instead.
- Calculating storage per unit instead of per cubic foot. Two products can have the same unit count but vastly different storage costs. A 0.3 cu ft product costs twice as much to store as a 0.15 cu ft product. Always model storage by cubic footage.
- Not connecting storage cost to sell-through velocity. Storage cost per unit depends on how fast you sell. A SKU with 30-day turns costs $0.04/unit in storage; the same SKU at 120-day turns costs $0.16/unit. Improving sell-through is the most effective way to reduce per-unit storage cost.