FBA Fulfillment Fee
Also known as: FBA Fee, Pick and Pack Fee
The FBA fulfillment fee is the flat per-unit charge Amazon takes to pick, pack, and ship an FBA order, priced by the unit's size tier and shipping weight.
The fulfillment fee is what FBA charges to handle the physical order: picking the unit from its bin, packing it, shipping it to the customer, and covering customer service and returns handling. Unlike the referral fee (a percentage of price), the fulfillment fee is a flat dollar amount determined by the unit's size tier and shipping weight, not its sale price.
Amazon assigns each unit a size tier (Small Standard, Large Standard, Large Bulky, and oversize tiers) from its packaged dimensions and weight, then looks up the fee on the current FBA rate card. Shipping weight is the greater of actual and dimensional weight. Apparel and dangerous-goods units have separate, usually higher, rate cards.
The fulfillment fee is the single largest variable cost on most low-priced FBA units, so it dominates margin math. Shaving packaging to drop into a smaller size tier or a lower weight band is one of the highest-leverage cost reductions available.
A 9 oz item in the Small Standard size tier is charged roughly a $3.30 fulfillment fee per unit regardless of whether it sells for $15 or $25 — the fee tracks size and weight, not price.