Summary

  • US FBA sellers can request extra capacity for announced future periods by offering a maximum reservation charge per cubic foot. Higher offers get priority when space is available.
  • Performance credits apply a 15% rate after eligible shipped FBA sales have been prorated by extra capacity as a share of the total limit. Credits stop at the reservation charge.
  • MCF sales do not qualify, ordinary FBA costs remain, and leaving approved capacity unused does not automatically cancel the reservation obligation.

Every warehouse has a limited supply of space and an apparently unlimited supply of merchants expecting a terrific month. The awkward part is that some of those merchants know something the warehouse does not. A product launch, a promotion or a change in customer appetite may be quite real before it becomes visible in past sales.

Amazon's US FBA Capacity Manager gives that private knowledge a price field. Sellers can ask for extra volume and specify the maximum reservation fee they would accept per cubic foot. As capacity becomes available, Amazon approves requests in descending order of the offered unit fee. A seller can argue with the forecast, provided the argument includes a potential bill.

This is a useful right. Allocation based entirely on yesterday's sales can make tomorrow's promising product look inconveniently unproven. Yet accepting every plea would turn the warehouse into a museum of other people's confidence. The reservation mechanism tries to extract a more serious signal than another hopeful spreadsheet.

Amazon Science's account of the design identifies precisely this information problem: sellers have plans for launches and promotions that forecasting systems cannot fully see. Handling exceptions through individual intervention was burdensome. A priced request gives the seller's expectations a way into a process that can compare many claims.

The result is more interesting than a simple auction for shelving. A successful seller may owe no reservation charge at all. Working out whether that makes the stock a good investment requires looking beyond the tempting zero.

An early bid need not mean an expensive one

Requests cover future periods for which estimated or confirmed limits have been announced. Sellers cannot submit them for the current period. The mechanism belongs in purchasing and production decisions, before a lorry full of confident inventory is already on its way.

Higher bids improve priority, but available capacity still determines what can be granted. The seller also need not pay the maximum offered. Under the current US help rules, requests granted in the same week receive the lowest per-cubic-foot reservation rate granted that week. If later requests receive a lower rate for the same usage period, earlier grants adjust downwards.

That protection matters to someone trying to place a manufacturing order. It reduces the fear of applying early only to watch a later applicant obtain a cheaper rate for the same period. The seller can seek planning certainty without necessarily locking in the price of being first to worry. The guarantee improves the timing of the decision; it does not improve the product.

There is no upfront payment when a request is submitted or granted. After the requested period ends, Amazon charges the reservation fee less earned performance credits. Sufficient qualifying sales can erase the whole reservation charge. Until the sales arrive, however, the obligation is contingent rather than imaginary.

The fraction before the headline percentage

Performance credits accrue at $0.15 for each dollar of qualifying sales. Applying 15% to the shop's entire turnover would make the proposal considerably more cheerful than the rules allow.

Amazon first considers sales of units shipped during the requested period in the storage type receiving the increase. It then prorates those sales by the additional granted capacity's share of the total capacity limit. The result is the sales base to which the credit rate applies.

The official US standard-size example starts with a limit of 1,000 cubic feet and adds 500, producing a total of 1,500. The additional share is one-third. If relevant sales are $105,000, the prorated amount is $35,000, generating up to $5,250 in credits. The help page displays a rounded 33%; the exact fraction, 500 divided by 1,500, explains the arithmetic.

This calculation does not follow individual boxes sitting in the extra space and discover which sales they caused. It allocates sales using authorised volume. That supplies a workable settlement rule. Estimating the extra demand or profit actually created by the capacity requires a separate exercise.

For illustration, add an assumed final reservation rate of $10 per cubic foot to the official volumes. That is a hypothetical price, not an observed award rate. The additional 500 cubic feet would carry a $5,000 reservation charge. The potential $5,250 credit would cancel $5,000, with no $250 cash prize left over. Credits are capped at the charge.

If relevant shipped sales were instead $60,000 at the same capacity limits, the one-third allocation would produce a $20,000 base and a $3,000 credit. The remaining reservation bill would be $2,000. Same space, different sales, rather less comfortable optimism.

A sale can be good business and still fail this test

The channel boundary is particularly revealing. Multi-Channel Fulfillment, or MCF, sales do not count towards performance credits. Only FBA sales qualify. A merchant may expand another channel successfully and improve the business without generating the credits expected by a careless all-sales forecast.

The dates create another boundary. Additional capacity may be accessible up to a month before the requested period, allowing inventory to be positioned in advance. Credits still depend on sales during the requested period. Capacity increases available through early access are excluded from the current period's ratio calculation. Permission to move stock early does not make the sales calendar equally flexible.

Sellers can set an expiry date for an ungranted request. If approval has not arrived by then, the request stops being considered. This acknowledges an elementary fact of manufacturing: an answer delivered after the purchasing deadline can be administratively positive and commercially useless.

Pending requests can be cancelled before they are granted or expire. Once granted, cancellation is confined to specified circumstances, including a confirmed base limit exceeding its earlier estimate; an associated automatic-cancellation feature is available. Merely leaving the granted space unused does not remove the reservation charge. The balance still depends on applicable credits.

Those details turn a volume request into a decision about product mix, channels and shipment dates. The physical question, “Will the boxes fit?”, is only the start of the commercial one.

Zero reservation fee is a small victory

Ordinary FBA charges remain, including fulfilment services and monthly storage based on average daily inventory volume. The goods also had to be bought, and someone financed the time between payment and sale. Clearing one fee does not clear the economics of the purchase.

A late promotion could raise eligible sales and reduce the reservation balance while sacrificing more contribution than it saves. The warehouse sees stock moving. The merchant may be watching profit leave with it. Chasing the credit becomes expensive when the target is treated as a certificate of commercial success.

We lack a particular seller's product margins, shipping calendar, channel mix and awarded rate; those would decide whether its request pays. The distinction between sales, credits and profit is already clear enough to keep them in separate columns.

Amazon announced the capacity system in January 2023 for introduction that March. Its enduring interest lies in how it allocates judgment and error. A seller gets a route to challenge a central forecast, while accepting a possible cost if the expected sales do not materialise. That is a meaningful commercial bargain. It deserves a better appraisal than counting the cubic feet won.