PrepLabelQuick answer: To make FNSKU labels, copy each product's FNSKU (the X00… code from your FBA inventory in Seller Central), enter it with the title, condition and number of units, choose your label stock (for example 2 × 1 in thermal or 30-up Letter sheets) and click Download PDF. Print at 100% scale and scan one test label before you label the whole shipment.
How to print FNSKU labels
- Find your FNSKUs. In Seller Central, open your FBA inventory and copy each product's FNSKU (it usually starts with X00). The inventory report download has the same codes in an fnsku column.
- Enter or import products. Type each FNSKU with its title, condition and the number of units, or import a CSV or Excel file with one row per product.
- Pick your label stock. Choose a thermal roll such as 2 × 1 in or DYMO 30334, or a sheet such as 30-up Letter (Avery 5160 size) or 21-up A4. On a part-used sheet, set the first free position.
- Download and print at 100%. Click Download PDF and print at Actual size with scaling turned off. For Zebra printers you can download ZPL instead.
- Test-scan one label. Scan a test label with a barcode scanner or the Test & scan tab before labeling the whole shipment, then cover any other barcodes on each unit.
What goes on an FNSKU label
An FNSKU (Fulfillment Network Stock Keeping Unit) label tells the fulfillment center which seller owns a unit. Amazon's item-label specification lists four things, and PrepLabel prints exactly those four and nothing else:
- A Code 128 barcode of the FNSKU, with clear space on both sides so scanners can read it.
- The FNSKU in plain text under the bars, for example X001ABC123.
- The product title, shortened in the middle when it's long so the size or colour at the end stays visible.
- The condition, such as New or Used - Very Good.
The code checker under each FNSKU flags typos: Amazon FNSKUs are 10 characters and usually start with X0, and some listings use the ASIN (B0…) instead. You can also print labels for your own SKUs, which is handy for multichannel stock.
Label sizes PrepLabel supports
| Label stock | Size | Typical printer |
|---|---|---|
| 2 × 1 in thermal roll | 50.8 × 25.4 mm | Rollo, Zebra, Munbyn and other 4-inch desktop thermal printers |
| 2.25 × 1.25 in roll (DYMO 30334 size) | 57.2 × 31.8 mm | DYMO LabelWriter |
| 3 × 1 in or 50 × 25 mm roll | 76.2 × 25.4 / 50 × 25 mm | Thermal printers; 3 × 1 suits long SKUs |
| 62 × 29 mm (Brother DK-1209 size) | 62 × 29 mm | Brother QL label printers |
| US Letter, 30 per sheet (Avery 5160/8160 size) | 2-5/8 × 1 in | Laser printer |
| A4, 21 / 24 / 27 per sheet | 63.5 × 38.1 / 33.9 / 29.6 mm | Laser printer (UK and EU) |
| A4, 40 or 44 per sheet | 52.5 × 29.7 / 48.5 × 25.4 mm | Laser printer |
| Custom roll or sheet | Any size you enter in mm | Any |
Thermal PDFs have one label per page at the exact label size, so the printer driver doesn't have to guess. If your labels are on a Seller Central sheet already, the PDF to thermal converter cuts each one out and puts it on its own 2 × 1 in page.
Printer settings that make labels scan
- Print at 100% / Actual size. “Fit to page” shrinks the bars, and shrunken barcodes are a common reason labels fail at receiving.
- Match the paper size. In the printer dialog, pick the label size that matches the PDF (for example 2 × 1 in or 50.8 × 25.4 mm), not Letter or A4.
- Tell PrepLabel your printer's resolution. Bars are snapped to whole printer dots: 203 dpi for most Rollo, Zebra and Munbyn printers, 300 dpi for DYMO LabelWriter and some Zebra models.
- Use a thermal or laser printer. Amazon recommends thermal or laser printing on white labels with removable adhesive. Inkjet ink can bleed into the gaps between bars.
- Calibrate once. If labels drift off the edge, run your printer's gap calibration and use the alignment test page in the Test & scan tab.
Why a barcode won't scan, and how to fix it
| Symptom | Likely cause | Fix |
|---|---|---|
| Label prints small in a corner | Paper size in the print dialog doesn't match the label | Select the label size and print at 100% |
| Bars look fuzzy or merged | Scaling, or the wrong printer resolution | Set 203 or 300 dpi under Printer and alignment |
| Faint or grey print | Darkness too low or old thermal labels | Raise darkness in the printer settings |
| Scanner reads a different code | The manufacturer barcode is still visible | Cover every other barcode on the unit |
| “Too long for this label” warning | Long SKU on a narrow label | Use a 3 × 1 in label or a shorter SKU |
Prep labels, bin labels and bulk printing
The Prep labels tab makes suffocation warnings sized from your bag dimensions (in English, French, German, Spanish, Italian and Dutch), sold as set / do not separate stickers and expiration date labels. The Bin labels tab prints location labels with QR codes for your shelves. For a whole shipment, import a CSV or Excel file with a quantity per SKU, or export ZPL for a Zebra printer. Every PDF you download is listed in the print log, which you can export as CSV.
Free, private and made for resellers
Seller guides report that Amazon stopped applying FNSKU labels for US sellers on 1 January 2026 and ended commingling on 31 March 2026, so most resellers now label every unit themselves (see FNSKU labeling requirements in 2026). PrepLabel is built for that job: it's free, needs no account, and runs entirely in your browser. Product lists, saved libraries and the print log stay on your device, and PDFs you convert are never uploaded.
Frequently asked questions
Is PrepLabel really free?
Yes. Every feature is free: unlimited FNSKU labels, CSV and Excel import, the Seller Central PDF converter, ZPL export, prep labels, bin labels, saved products and the print log. There is no account and no paid tier.
Do I need to sign in to Seller Central or give PrepLabel my account?
No. PrepLabel never connects to Amazon. Copy the FNSKU codes from your inventory page or inventory report in Seller Central and paste or import them here.
Is PrepLabel affiliated with Amazon?
No. PrepLabel is an independent tool and is not affiliated with, endorsed by or sponsored by Amazon. Always check current labeling rules in Seller Central.
What barcode type does an FNSKU label use?
Code 128. PrepLabel encodes FNSKUs in Code 128 subset A, the variant Amazon's item-label specification names, draws every bar as vector artwork and snaps bar widths to your printer's dots.
Can I print on a partly used sheet of Avery 5160 labels?
Yes. Choose the 30-per-sheet Letter stock and set Start at label to the first unused position. Labels are counted left to right, top to bottom.
Does PrepLabel add its name or a watermark to my labels?
Never on a unit label or a warning label. Those carry only their own content. The only credit is a small line in the outer margin of full-sheet printouts and on the alignment test page.
More PrepLabel guides
Last updated · Written by the MiniTools team. General information, not legal advice. Amazon changes its rules, so confirm current requirements in Seller Central.