FNSKU labels: print them, or pay someone.
An FNSKU is the barcode Amazon issues for one seller's units of one product, so your inventory stays tracked separately from every other seller's identical item. It is a physical sticker that goes on the outside of the unit and covers whatever barcode was there before. Amazon ended commingled, manufacturer-barcode inventory on March 31, 2026, so if you buy to resell, every unit you send now needs its own FNSKU label. The only real question left is who applies it.
FNSKU vs UPC vs ASIN.
These get used interchangeably and they are not interchangeable. One is a seller-specific sticker, one is a product-wide barcode owned by the brand, and one is not a barcode at all.
| Code | What it identifies | Who issues it | Where it goes |
|---|---|---|---|
| FNSKU | One seller's units of one product. Two sellers of the identical product get different FNSKUs, which is the whole point: it keeps your inventory tracked separately inside the fulfillment center. | Amazon, per seller-ASIN pair. Generated in your own account and printed from the Label products step or from Manage Inventory. | A physical sticker on the outermost layer of the unit, covering any other visible barcode. It starts with an X. |
| UPC (and EAN, JAN, ISBN) | The product itself, across every retailer on earth. Identical units from the same manufacturer share one UPC no matter who sells them. | GS1 and its national equivalents, to the brand owner or manufacturer. Amazon calls this family the manufacturer barcode. | The manufacturer's own packaging. When an FNSKU goes on, this one has to be covered. |
| ASIN | The Amazon catalog listing, not a physical unit. Every seller on a listing shares its ASIN. | Amazon, when the catalog entry is created. | Nothing. It is a catalog key, not a barcode you stick on anything. It does appear as text on the printed FNSKU label. |
Resellers no longer have a choice.
Amazon's own wording, on the barcode requirements page: as of March 31, 2026, brand owners can continue to use manufacturer barcodes without stickers, and resellers are required to use Amazon barcodes for products even if they have a manufacturer barcode. That is the end of the stickerless, commingled path for arbitrage and wholesale sellers. The exception is narrow and belongs to the brand owner of the product; eligibility is checked per ASIN on Seller Central: Use manufacturer barcodes for FBA.
The other half of 2026 matters just as much for the arithmetic further down this page. Amazon stopped offering prep and item labeling services in the US store on January 1, 2026. Before that you could pay Amazon $0.55 per unit to apply the label at the fulfillment center, for standard and oversize alike. Amazon will not do it now at any price. Source: Seller Central: FBA Prep Service. It is still the most useful benchmark on the page, because it is the one number Amazon itself once put on the job.
The 6 rules Amazon actually writes down.
Read off live Seller Central help pages on September 19, 2026. Each rule names the page it came from. Anything we could not confirm on a Seller Central page is not on this list.
Between 1 x 2 inches and 2 x 3 inches
Amazon states the dimensions as a band, not a single size: 1 x 3 inches or 2 x 2 inches are both inside it. For laser printing, the supported letter-paper layout is 30 labels per page at 1 x 2 5/8 inches, which is the sheet most sellers buy.
Black ink on white, non-reflective labels with removable adhesive
All three properties are stated. Reflective or glossy stock is named in Amazon's own problem list as a cause of unscannable barcodes, and removable adhesive is what lets a receiver or a prep center correct a mislabel without destroying the packaging.
300 dpi or greater, thermal or laser, never inkjet
Amazon's instruction is explicit: the seller tools are optimized for thermal printers, laser printers also work, and do not use inkjet printers to print Amazon barcodes. The label must stay readable and scannable for 24 months, so Amazon also asks you to scan-test your own barcodes periodically and to clean or replace print heads. If your printer tries to scale the PDF, set scaling to None or 100%; a shrunk barcode stops scanning.
Not on a curve or a corner, and 0.25 inch clear of the package edge
Both are stated as placement requirements. Amazon separately requires 0.25 inch of white space on the sides of the label content and 0.125 inch top and bottom, and the printed label has to carry the ASIN or FNSKU, the product name, and the item condition, matching the format Seller Central generates.
Cover every other visible barcode
Two named exceptions survive: serial number barcodes and Transparency authentication codes. Everything else, the manufacturer UPC included, gets covered. In a case pack, every unit needs its own Amazon barcode and the barcodes on the case itself have to be removed.
Still scannable after prep materials go on
Amazon puts this in the placement list, which is the rule people break by polybagging over a label and creasing it, or by bubble-wrapping a labeled unit. If the bag or wrap is the outer layer, the label belongs on the bag or wrap.
What a bad label actually costs, and what it does not.
Amazon states the labeling consequence plainly: a product that requires an Amazon barcode and arrives without one is marked defective, Amazon applies a barcode sticker itself, and the defect is reported on your Inbound Performance Dashboard. Placement failures can delay processing and may result in unplanned prep service fees.
Amazon's inbound defect fee is a different fee, and it is worth being precise because the two are conflated everywhere. It runs $0.32 to $5.72 per unit by size tier and weight, and Amazon's published table charges it for units that are misrouted, deleted, or abandoned. Not for a sticker in the wrong place. Budget for both separately, and treat any single point estimate of the defect fee as a number somebody made up.
What labeling actually costs you.
Labels are cheap. Hours are not. The table below is arithmetic run on the stated assumptions, not a measurement of anybody's warehouse. Change the assumptions and the table changes with them.
| Per month | Label stock ($0.02 to $0.04 each) | Your hours (20 to 40 sec per unit) | Those hours at $40 | Monthly total |
|---|---|---|---|---|
| 200 units | $4 to $8 | 1.1 to 2.2 hours | $44 to $89 | $48 to $97 |
| 500 units | $10 to $20 | 2.8 to 5.6 hours | $111 to $222 | $121 to $242 |
| 1,500 units | $30 to $60 | 8.3 to 16.7 hours | $333 to $667 | $363 to $727 |
Notice what the table does not do: it does not get cheaper per unit as volume rises. At $40 an hour, DIY labeling costs a flat $0.24 to $0.48 per unit at every volume in the table, because peeling and sticking has no economies of scale. The printer is the only fixed cost that amortizes, and it is the smallest number here.
Label stock
$0.02 to $0.04 per label
1 x 2.125 inch thermal stock at typical case pricing. Assumption. The 30-up laser sheet path is roughly ten times cheaper per label, under a cent, but it costs you a laser printer and sheet handling.
Time per unit
20 to 40 seconds
Peel, cover the manufacturer barcode, apply flat, spot-scan. Assumption, and it is labeling only: it excludes receiving, inspecting, bagging, and boxing. Our supplies page uses 2 to 4 minutes for the whole prep job.
Your hour
$40
Assumption, used only to turn hours into a number in the table. Substitute your own; the break-even formula below does not depend on it.
Thermal label printer
$75 to $200, one time
The range between the budget and workhorse direct-thermal printers priced on our own supplies page (Amazon prices checked August 16, 2026). Assumption, and prices move.
Laser plus sheet labels
$0 extra if you already own a laser
Assumption. If you own only an inkjet this path is closed, not cheap: Amazon says do not use inkjet printers to print Amazon barcodes.
What the other side of the trade costs.
Across the 2026 Pricing Index, the median US entry rate is $1.30 per unit across 44 verified centers with published rate cards, deduplicated. Figures are the June 12, 2026 snapshot the index publishes.
That rate is for a prep job, not a sticker. It typically covers receiving, inspection, the FNSKU label, and handoff. Comparing it line for line against 30 seconds of your own time is the mistake this page exists to stop. Some centers do publish a standalone FNSKU-only line below $1.00; we verified more than one in the published directory and name none, because those lines move and this page is not a ranking surface.
The line item most DIY-versus-outsource comparisons omit: 41% of those centers charge a one-time setup fee, median $87. On a 200-unit month that fee alone is worth roughly two months of label stock. Ask what it is before you compare per-unit rates. The full fee benchmarks break down what each tier includes.
Outsourcing labeling beats doing it yourself when your own hour is worth more than:
hourly rate = (price per unit minus label stock) x 3,600 / seconds per unit
Worked once, on the only per-unit labeling price Amazon itself ever published: at $0.55 per unit, $0.03 of label stock, and 30 seconds of work, the break-even is about $62 an hour. Below that rate, printing your own labels is cheaper.
Swap in a $0.30 FNSKU-only line and the break-even drops to about $32 an hour. Which is the real finding here: outsourcing labeling by itself is a close call that turns entirely on the rate card you get. Outsourcing the whole prep job, at 2 to 4 minutes a unit instead of 30 seconds, is a different and much easier decision.
Compare the DIY hours above against verified centers' published FNSKU rates: every published rate card in the full prep center list is filterable and carries a last-verified date, and the services guide says which centers name FNSKU labeling on their own service list.
We will put your volume in front of verified centers.
Tell us your monthly units and what you sell. We hand-match you to 2 or 3 prep centers that cleared our 4-point verification standard, with their current rate cards and the FNSKU line called out. Free, no account required.
When a label is not enough.
A correctly printed FNSKU on the wrong layer of packaging is still a receiving defect. Four situations where labeling is the smaller half of the job:
- Poly bags. Apparel, textiles, small parts, anything that sheds or leaks. The bag becomes the outer layer, so the FNSKU goes on the bag, not on the product inside it. Transparent, 1.5 mil minimum, fully sealed, with adult products reversing the transparency rule.
- Suffocation warnings. Required on any bag with an opening of 5 inches or more, printed or permanently affixed near the opening. Buying bags with the warning pre-printed removes a whole labeling step, which is why it is the default buy.
- Expiration dating. Dated goods need the date on the unit and on the master case in an accepted format, with enough shelf life remaining at receipt. This is its own labeling pass, on top of the FNSKU, and it is where supplement and food sellers lose shipments.
- Bundles and sets. A multi-unit bundle carries one FNSKU on the outer bag plus a visible do-not-separate marking. Without the marking, receivers split the bundle into its component units and the SKU stops existing.
The full rulebook for all of these, with category-by-category requirements and the failure mode for each, is on our FBA prep requirements page. What each of them costs as a rate-card line is on the prep services guide.
Common FNSKU questions.
Can I print FNSKU labels at home?
Does Amazon still allow manufacturer barcodes?
What size does an FNSKU label have to be?
What happens if the FNSKU label is wrong or missing?
Can a prep center apply FNSKU labels for me?
Related references.
Amazon FBA prep requirements
Every other prep rule a labeled unit still has to clear: polybag specs, drop tests, expiration formats, hazmat.
Open the requirements →
FBA prep supplies checklist
The printers, label stock, and bags behind the per-unit costs on this page, each priced on a stated date.
Open the checklist →
What FBA prep centers charge
Per-unit benchmarks by tier, and the fixed fees that decide whether a cheap per-unit rate is actually cheap.
Open the fee benchmarks →
FBA Prep Pricing Index 2026
Where the $1.30 median and the 41% setup-fee finding on this page come from, rate card by rate card.
Open the index →
FBA prep services explained
FNSKU labeling is one line on a 17-service taxonomy. The rest of the rate card, defined.
Read the services guide →
Full FBA prep center list
Every published center, filterable, each with a rate card and a last-verified date.
Browse the full list →
What is FBA prep?
The primer, if labeling is the first prep decision you have had to make.
Read the primer →