Oversize
Also known as: FBA Oversize, Bulky, Large Bulky
Oversize refers to FBA size tiers for large or heavy units that exceed standard dimensions, carrying substantially higher fulfillment and storage fees.
Amazon sorts every FBA unit into a size tier from its packaged dimensions and weight. Units that exceed the Large Standard limits fall into bulky/oversize tiers — Large Bulky and the Extra-Large tiers (graded by longest side and weight) — which have their own, much higher fulfillment-fee rate card.
Oversize units cost more at every step: higher per-unit fulfillment fees, higher monthly storage rates (bulky storage is priced per cubic foot and spikes in the Q4 peak), and they consume restock and storage capacity faster. Dimensional weight matters even more here, since these items are often bulky relative to their mass.
For sellers, the size tier is a make-or-break margin input. A product that crosses from Large Standard into an oversize tier can see its fulfillment fee jump several dollars, so reducing packaging to stay under a tier boundary is a high-value optimization — and sourcing decisions should account for the oversize fee structure up front.
A 24 × 18 × 14-inch storage bin weighing 11 lb lands in an oversize tier. Its FBA fulfillment fee runs well above a Large Standard unit, and it accrues bulky-rate storage fees — so the seller prices it to absorb those costs.