FBA Capacity Limits: How the Cubic-Feet System Works | Inventory Hero
·5 min readIPI
FBA Capacity Limits: How the Cubic-Feet System Works
FBA capacity limits set a monthly cubic-feet allowance for your inventory. How the limit is set, how Capacity Manager works, and how to plan around it.
Amazon gives you a single monthly capacity allowance measured in cubic feet, covering how much inventory you can hold in the fulfillment network and send in. It replaced the older separate storage and restock limits. Your allowance is set from your IPI score, your recent sales and forecast, and your capacity usage history, and you can request more through Capacity Manager.
How is my FBA capacity limit determined?
Amazon sets it from a few inputs: your IPI score (healthier inventory earns more room), your sales history and demand forecast (faster-growing accounts get more), and how you have used capacity in the past. IPI is the input most within your control, so improving inventory health is the durable way to earn more capacity over time.
Andrew Erickson is the founder of Inventory Hero. He has spent years working with Amazon FBA sellers on demand forecasting, restock planning, and the cash flow side of running a private-label brand. Inventory Hero exists because every spreadsheet-based inventory system he tried eventually broke — usually right before Q4.
You generally cannot send in inventory beyond your allowance, and if your stored inventory exceeds the limit, an overage fee typically applies per cubic foot over. The practical effect is you are blocked from restocking until space frees up or your limit rises, so the real cost is usually the stockout risk on a good SKU, not just the fee.
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FBA capacity limits are Amazon's system for capping how much inventory you can hold and send in, expressed as a single monthly allowance measured in cubic feet. The short version: it replaced the older separate storage and restock limits, your allowance is set from your IPI, sales, and history, and you can request more through Capacity Manager for a fee. Below is how the system works and how to plan around it.
A capacity limit is a single monthly allowance, in cubic feet, for the total inventory you can have in Amazon's fulfillment network and send to it. Amazon consolidated the older, separate storage limits and per-ASIN restock limits into this one volume-based number, so instead of juggling multiple caps you manage one allowance.
The mechanics have evolved since the system rolled out, and Amazon continues to adjust them, so treat this as the current shape and confirm the specifics in your own FBA capacity dashboard. The practical experience, though, is stable: you have a volume budget, and when it is full you cannot send in more.
Your IPI score. Healthier inventory generally earns more capacity; a weak IPI tightens it. This is the input most in your control.
Your sales and forecast. Growing, faster-selling accounts are granted more room, because Amazon expects the inventory to move.
Your capacity history. How you have used your past allowance factors in; chronically filling it with slow stock does not help your case.
Because IPI is the controllable lever, keeping inventory healthy is how you earn more capacity durably, rather than relying on one-off requests; see how to improve your IPI score for the actions that raise it. Baseline allowances vary widely by IPI and sales history, so there is no standard number to compare yourself against; read your own allowance in the capacity dashboard and judge it against your actual flow, not another seller's.
Because the allowance is volume, it helps to translate a shipment into cubic feet. Take a carton measuring 18 by 14 by 8 inches: that is 2,016 cubic inches, and since a cubic foot is 1,728 cubic inches, the carton is about 1.17 cubic feet. A 50-carton shipment is therefore roughly 58 cubic feet.
If your monthly allowance is, say, 1,000 cubic feet, that one shipment consumes about 6 percent of it. Now the trade-off is visible: a dense, fast-selling SKU that fits many units per cubic foot is cheap to store and turns quickly, while a bulky, slow SKU can eat a large slice of your allowance for months of little return. When capacity is tight, this arithmetic is the argument for sending in your dense, fast movers and clearing the bulky slow stock, the same logic you would apply to spending limited cash.
When your baseline allowance is not enough, Capacity Manager is the tool to request more:
Request additional capacity above your baseline for the period.
Reserve cubic feet for a fee. You can secure extra space at a reservation fee Amazon sets, charged per cubic foot per month, offset by a performance rebate credited on how much of that reserved inventory you actually sell through during the period. So it rewards selling, not just occupying: reserve space you will sell out of, or the rebate is small and you have simply paid for room.
Check the current rate first, then compare to a 3PL. Amazon adjusts the per-cubic-foot fee, so confirm the current rate in Capacity Manager before committing. Then run the comparison: roughly, if the reservation fee per cubic foot per month exceeds your 3PL's cost per cubic foot (its pallet rate divided by pallet volume) plus the shipping to drip-feed into FBA, the 3PL is cheaper. Factor the rebate, though: if you will genuinely sell through the reserved space, the net reservation cost drops and can tilt the call back toward reserving.1
Reserving space is worth it ahead of a proven demand spike you will sell through; it is not worth it to house the slow stock that tightened your limit in the first place.
You are blocked from sending more. You generally cannot create inbound shipments beyond your capacity, so you simply cannot restock until room frees up or your limit rises.
An overage fee applies to stored inventory over the limit. If your held inventory exceeds the allowance, Amazon typically charges an overage fee per cubic foot over, on top of normal storage. Amazon sets and adjusts that per-cubic-foot rate, so check the current figure in your capacity dashboard rather than assuming a number.1
The fee is real, but the bigger cost is usually operational: being unable to restock a healthy SKU is a stockout waiting to happen, which is far more expensive than the overage itself.
FBA capacity limits give you one monthly cubic-feet allowance, set from your IPI, sales, and history, with Capacity Manager to reserve more for a per-cubic-foot fee and an overage fee if you exceed it. Spend the budget on your best-returning SKUs, keep excess and stranded stock out of it, watch your IPI, and use a 3PL for overflow. For the practical side of being capped, see Amazon restock limits; for the score that sets your allowance, the Amazon IPI score; and for raising it, how to improve your IPI.
The FBA capacity limit system (the monthly cubic-feet allowance, Capacity Manager reservation fee and performance rebate, and per-cubic-foot overage fee) is described in Amazon Seller Central's FBA capacity limits and Capacity Manager help pages (sellercentral.amazon.com). Amazon sets and revises these rates; confirm current figures in your capacity dashboard. ↩↩2