Amazon FBA storage fees are the second-biggest cost line for most sellers after referral fees, and the one that catches teams off guard most often. They are billed monthly, calculated on cubic feet not units, and they spike during Q4. Long-term surcharges add a second layer for anything aged past Amazon’s thresholds.

This guide explains how storage fees actually work and how to spot the inventory that’s about to cost you.

TL;DR: Amazon charges monthly storage fees based on cubic feet your inventory occupies. Standard-size and oversize products have different rates, and rates roughly double in peak season (October to January). Anything aged past 365 days triggers a long-term storage surcharge. Tracking storage costs properly means joining the storage fee report to your inventory aging data, then forecasting what hits next month before it does.

How monthly storage fees work

Charged on cubic feet, not unit count. The bigger your products, the more you pay. Categories:

• Standard-size storage — lower per-cubic-foot rate, applies to most consumer goods.
• Oversize storage — higher rate, applies to bulky products.
• Dangerous goods — separate rate for hazmat-classified inventory.

Rates vary by Amazon marketplace. US, EU and JP all have their own schedules.

Peak season storage surcharge

From October through January, monthly storage rates roughly double. The surcharge applies to all stored inventory, not just inventory that arrived for the holidays. This catches sellers who keep average storage models and don’t account for the seasonal multiplier.

How to plan for it

• Forecast holiday inventory needs in early Q3.
• Send only what you need plus a reasonable buffer.
• Pull aged inventory out before October to avoid paying peak rates on slow movers.
• Use the FBA Capacity Manager (available in Seller Central) to track allocated space.

Long-term storage surcharges

Beyond the monthly fee, Amazon charges a long-term surcharge on inventory aged past a threshold. The current standard is 365 days, with historic tiers that may apply depending on the period.

The surcharge is significant — typically dollars per cubic foot per month, on top of the regular storage fee. For low-velocity SKUs it can quickly exceed the unit’s margin.

What to watch

• SKUs aged 270-364 days. About to trigger long-term surcharges. Action window for promo or removal.
• SKUs aged 365 days plus. Already paying the surcharge. Decision time — promote, remove or dispose.
• Aging trend. If your aged inventory is growing month over month, the underlying problem is sourcing or demand.

How to spot aged inventory before it hits

The right time to act on aging inventory is two to three months before the surcharge fires — when there is still time for a sell-through promo. Not after.

That means tracking, per SKU per warehouse:

• Days since first received in FBA.
• Current units on hand.
• Trailing 30-day units sold.
• Days of cover at current velocity.
• Forecast date the surcharge fires.

Combine those and you have a working aging dashboard. Without joining inventory aging data to current velocity, you are flying blind.

What to do with aged inventory

• Markdown promotions. Lower price plus ad spend bump can clear stock before surcharge.
• Lightning Deals or Coupons. Short-term sell-through boost.
• Removal orders. Send to your warehouse or 3PL to sell elsewhere.
• Disposal orders. If the unit cost no longer makes sense even with discounting.

The right action depends on margin math, not gut feel. Removal costs money. Disposal costs money. Holding costs money. The cheapest option depends on the SKU.

The bottom line

FBA storage fees punish slow movers. The numbers are predictable, but only if you have the data joined and tracked. Most sellers find out about long-term surcharges after they fire. Few catch them in time to act.

DataDoe’s Amazon data layer joins inventory aging, storage fees and velocity into one query so you can spot the surcharge before it hits, not after.