The complete guide to FNSKU labels, box labels, and pallet labels — sizes, barcode types, DPI requirements, placement rules, and how to avoid $0.20/unit FC relabeling fees.
Amazon FBA requires three types of labels: FNSKU unit labels (1×2 inches, Code 128 barcode, on every unit), box labels (4×6 inches, GS1-128, on every carton), and pallet labels (4×6 inches, on all 4 sides of each pallet for LTL shipments). Getting these wrong costs $0.20/unit in relabeling fees or results in shipment holds.
Three distinct label types, each with strict specifications enforced at Amazon fulfillment centers.
| Label Type | Size | Barcode | Min DPI | Placement | Required On |
|---|---|---|---|---|---|
| FNSKU Unit Label | 1×2 inches (min 1×1") | Code 128 | 300 DPI min | Outside of unit/poly-bag | Every individual sellable unit |
| Box / Shipment Label | 4×6 inches | GS1-128 | 203 DPI+ | Side of carton (not top/bottom) | Every carton in the shipment |
| Pallet Label | 4×6 inches | Code 128 / GS1-128 | 203 DPI+ | All 4 sides, upper third | Every pallet in LTL shipments |
An FNSKU (Fulfillment Network Stock Keeping Unit) is a 10-character identifier starting with X0 (e.g., X001234567) that Amazon uses to track your specific inventory — separate from other sellers' inventory of the same ASIN. It is generated by Amazon in Seller Central and is unique to your account + ASIN combination.
Most WMS and ERP systems export FNSKU labels as ZPL files. Zentralabel converts them to print-ready PDFs at the correct 4×6 size, 300 DPI, in seconds.
Convert ZPL to PDF FreeAmazon FCs reject shipments for these errors. Each one either costs $0.20/unit or delays inventory receipt by days.
| Rejection Reason | Root Cause | How to Fix |
|---|---|---|
| Unreadable barcode | Low DPI, smeared ink, or insufficient quiet zone | Print at 300 DPI min. Test-scan with phone before shipping. |
| Wrong barcode type | Using ASIN or UPC instead of FNSKU | Generate labels from Seller Central's Print Item Labels. |
| Label over expiration date | FNSKU label covers required expiration date | Reposition label to a clear area of packaging. |
| Mismatched box count | Shipped 5 boxes, declared 4 in system | Always update box count in Seller Central before shipping. |
| Commingled UPC visible | Old manufacturer barcode not fully covered | Use opaque label stock to fully cover original barcodes. |
| Wrong label size | Box label printed at wrong dimensions | Use 4×6" label stock. Print from Seller Central at 100% scale. |
Yes. FNSKU labels can be printed on any inkjet or laser printer at 300 DPI on white label stock. For thermal printing, a Zebra or Rollo thermal printer is ideal. Box labels (4×6) require either a thermal printer or a standard printer with 4×6 label paper. Inkjet and laser printers work but require the ink to be fully dry and sharp — smeared barcodes cause scan failures.
In Seller Central, go to Manage Inventory → find your product → Print Item Labels. You can also access them via Inventory → Manage FBA Shipments during shipment creation. Amazon generates them as PDFs. If your workflow uses ZPL (e.g., from a WMS), convert the ZPL to PDF using Zentralabel.
If the barcode is unreadable or the wrong type: Amazon may charge a $0.20/unit labeling fee, hold your shipment as a 'problem shipment,' or return the entire shipment. For LTL with incorrect pallet labels, Amazon may refuse the delivery entirely. These costs add up quickly on high-volume FBA shipments.
No. You can label units yourself or have your prep center do it. Amazon's labeling service (FBA Label Service) costs $0.55/unit and is only available if you opt into it. It's more cost-effective to label yourself or use a prep service for anything above a few hundred units.