Technical Specifications
- Standard
- Code 128 linear symbology (ISO/IEC 15417) encoding 10-character FNSKU
- Payload Format
- X00... (merchant-specific) or B00... (ASIN-matched) FNSKU identifier
- Label Dimensions
- 1" × 2-5/8" (Avery 5160, 30 per sheet) or direct thermal roll (e.g. 2.25" × 1.25" / 2" × 4")
- Mandatory Contents
- Code 128 barcode + human-readable FNSKU, product title, and item condition (e.g. "New")
- Quiet Zones
- 0.25" (6.35 mm) side margins and 0.125" (3.18 mm) top/bottom margins mandated by Amazon
- Printing Specs
- 300 DPI thermal or laser printing; client-side generation ensures seller data is never stored
Standard Industry Use Cases
- Item-level unit labeling for Fulfillment by Amazon (FBA) inbound shipments
- Avery 5160 / 30-up US Letter label sheets on laser printers
- Direct thermal shipping printers (Rollo, Zebra, MUNBYN, Brother) for single rolls
- Covering manufacturer UPC/EAN barcodes to prevent Amazon inventory commingling
- Private label FBA inventory preparation and Seller Central compliance
Key Benefits of Amazon FBA / FNSKU
Amazon's White Space Built In
The Amazon layout keeps 0.25" clear on the sides and 0.125" at the top and bottom, the margins Amazon asks for around the barcode and text.
Avery 5160 & Thermal Roll Ready
Print 30-up US Letter sheets on a laser printer, or single labels on MUNBYN, Rollo and Zebra thermal printers.
Text Always Matches the Bars
The FNSKU printed under the barcode is the value the barcode encodes, so a typo can't leave the text and the bars saying different things.
What Code Do I Need for My Product? (Customer Decision Guide)
Choosing the right barcode format depends on where your product is sold, the packaging substrate, and scanner infrastructure:
Manufacturer barcode or Amazon barcode (FNSKU)?
US, since 31 March 2026: if you are the brand owner with the Brand Representative role in Amazon Brand Registry, and the product has one scannable UPC, EAN or ISBN matching one ASIN, you can send it with the manufacturer barcode. Resellers must use Amazon barcodes. Products without a manufacturer barcode, or with a GTIN exemption, need Amazon barcodes. Amazon.in: Amazon barcodes by default; only books can go stickerless. More: Do I need a barcode to sell on Amazon?
Which printer for FBA labels?
A thermal printer (Amazon's own fulfilment centres use direct thermal Zebra GX430t printers) or a laser printer with Avery 5160 sheets. Not inkjet: Amazon says not to use it. Either way, 300 dpi or more.
Amazon's Label Rules (Seller Central help, checked 12 Oct 2026)
- Cover every other barcode on the unit (UPC, EAN, ISBN) with the FNSKU label, except serial-number and Transparency codes.
- Labels must be 1" × 2" to 2" × 3", black on white, non-reflective, with removable adhesive. Our template is 1" × 2⅝" (Avery 5160 size).
- Don't put the label on a curve or corner, keep 0.25" between the label and the edge of the package, and make sure it still scans after poly-bagging or other prep.
- Use a thermal or laser printer at 300 dpi or more, never inkjet. Labels must stay scannable for 24 months.
- Amazon India adds: don't tape over labels, and don't use QR codes on them.
Frequently Asked Questions
What is an Amazon FNSKU and how is it different from a UPC or ASIN?
An ASIN (Amazon Standard Identification Number) is Amazon's internal catalog identifier for a product page. A UPC is a universal retail GTIN assigned to the product packaging. An FNSKU (Fulfillment Network Stock Keeping Unit) is an Amazon-exclusive fulfillment barcode (typically starting with "X00") that ties an individual physical item directly to your specific seller account. This prevents commingling with identical inventory sold by other merchants in Amazon fulfillment centers. If you sell via FBA, Amazon usually requires each unit to carry an FNSKU barcode.
What barcode symbology does Amazon FBA require for FNSKU labels?
Amazon FBA mandates Code 128 (specifically Code 128-A, B, or C) for all FNSKU item barcodes. The barcode must encode exactly the 10-character FNSKU string with no extra digits, spaces, or prefixes. The human-readable FNSKU text must be printed cleanly directly beneath the bars. Our generator uses calibrated Code 128 vector rendering that complies precisely with Amazon Seller Central packaging requirements.
What mandatory text must appear on an Amazon FBA item label?
Under official Amazon FBA label guidelines, every unit label must contain three key elements: 1) The Code 128 barcode with human-readable FNSKU digits beneath; 2) The product title or item description (truncated cleanly to fit); and 3) The mandatory item condition line (e.g., "New", "Used - Like New", "Used - Good", or "Refurbished"). Furthermore, labels must include at least 0.25" (6.35 mm) quiet zones on the left and right sides and 0.125" (3.18 mm) at the top and bottom.
Can I print Amazon FBA labels on Avery 5160 sheets with an office printer?
Yes. UniversalCodeMaker includes a built-in Avery 5160 PDF label maker. Standard Avery 5160 sheets feature 30 labels per US Letter sheet (1" × 2-5/8" per label). Amazon explicitly recommends laser printing for label sheets because inkjets can smear when moisture or handling occurs during transit. Ensure your PDF print dialog is set to "Actual Size" or 100% scaling—never select "Fit to Page", which shifts label alignment.
Do I need to cover the existing manufacturer UPC or EAN barcode on the box?
Yes! Amazon FBA scanning policy strictly requires that only one scannable barcode is visible on the exterior packaging of each unit. If your product packaging already has a pre-printed UPC, EAN, or manufacturer barcode, you must apply the FNSKU label directly over the original barcode to cover it completely. Leaving two barcodes exposed leads to scanning confusion at fulfillment centers, delayed receiving, and unplanned prep fee penalties. For more details, see our Amazon Barcode Guide.
Are my private Amazon ASINs, FNSKUs, or seller SKU lists stored on your servers?
No. UniversalCodeMaker operates 100% inside your local web browser using client-side JavaScript. Your confidential Amazon FNSKU numbers, private-label product titles, inventory counts, and SKU lists never touch an external server and are never uploaded or tracked. Your catalog data remains completely private on your local machine.