Amazon FBA Prep Requirements: Labels, Packaging, and What Gets Rejected

Amazon's fulfillment centers operate with high throughput. When a product arrives improperly labeled or packaged, Amazon either returns it to the carrier (at your shipping cost) or performs "unplanned prep" — handling the packaging issue on your behalf and charging a per-unit fee ($0.25–$3.00+ per unit depending on the prep type).

For a shipment of 500 units requiring unplanned labeling, the fee alone can be $125–750. Multiply this across multiple shipments as your business scales, and prep errors become a significant margin drain. Correct prep before shipment is always cheaper.

More importantly, consistent prep errors can result in Amazon restricting your ability to use FBA for certain products, or requiring Amazon Prep service (where Amazon preps your products at an additional fee). Understanding requirements upfront avoids these outcomes.

FNSKU (Fulfillment Network Stock Keeping Unit) is Amazon's internal barcode that identifies your specific product-seller combination. Unlike UPC barcodes (which identify the product globally), FNSKU tells Amazon that this specific unit belongs to your seller account.

FBA requires every unit to have an FNSKU label that covers or replaces any existing barcode. If the manufacturer's barcode (UPC, EAN, JAN) is visible alongside the FNSKU, Amazon's scanner may read the wrong barcode and attribute the inventory to a different seller — causing inventory mix-up.

Generating FNSKU labels: go to Seller Central → Manage Inventory → select the product → Print Item Labels. FNSKU labels are free to generate. Print on standard Avery 5160 label sheets (1" x 2-5/8") or equivalent. Apply to each unit before sending to Amazon. The label must be scannable — test scan before shipping.

Barcode exemption: if you have Amazon's "virtual tracking" enabled (available under certain conditions), Amazon can track your inventory without FNSKU labels using the manufacturer barcode. However, this requires that your product's UPC/EAN is unique to your product and not shared with other sellers. Most new international brands should use FNSKU labeling for reliability.

Poly bag requirement: products that could spill, leak, or contaminate other products must be poly-bagged. Amazon also requires poly bags for apparel, fabric items, and products subject to moisture damage. Poly bags must be transparent and have a suffocation warning if the opening exceeds 5 inches in diameter.

Suffocation warning text: "WARNING: To avoid danger of suffocation, keep this bag away from babies and children. Do not use this bag in cribs, beds, carriages, or playpens. This bag is not a toy." This text must appear prominently on the bag. Pre-printed bags with this warning are available from packaging suppliers.

Bubble wrap: fragile products (glass, ceramics, electronics) must be bubble-wrapped or otherwise protected so the item withstands a "drop test" (dropped from 4 feet onto a hard surface without damage). Amazon's receiving team does not carefully handle items — packaging must survive normal warehouse operations.

Sets and bundles: if you're selling a multi-piece set (e.g., 3-pack, gift set), label the outer package "Sold as a set, do not separate" so receiving staff do not open and process individual items separately. Each set must be in a single, sealed unit of packaging.

Expiration dates: products with expiration dates (food, supplements, cosmetics with a "best by" date) must display the expiration date in MM/YYYY format on the unit. Lots expiring within 90 days of receipt at Amazon may be rejected. Send inventory with at least 6 months of shelf life remaining to be safe.

Master carton labeling: each carton sent to Amazon must have a shipment ID label (generated in Seller Central when creating the shipment plan) plus the standard Amazon box-content label. If sending multiple cartons from one shipment, number them (e.g., "1 of 4", "2 of 4"). Improperly labeled cartons cause receiving delays.

Pallet requirements: if shipping on pallets (large shipments), pallets must be ISPM 15 certified (heat-treated wood, marked with the HT symbol), 40×48 inches standard GMA pallet size, stacked to a maximum 50 inches (pallet + products), and wrapped in stretch wrap at least 4 layers. Do not double-stack pallets.

Prep checklist to use before every shipment: FNSKU label on every unit (covering manufacturer barcode), poly bag where required (with suffocation warning), bubble wrap for fragile items, set/bundle label on multi-piece units, expiration date visible (MM/YYYY), shipment ID label on every master carton, correct number of units per carton matching the shipment plan.