Amazon FNSKU: What It Is and How to Create Your Barcode

As of January 2026, Amazon no longer applies FNSKU labels for sellers. Every FBA seller in the U.S. is now responsible for labeling their own products before sending inventory to Amazon's fulfillment centers.

If you're unsure what an FNSKU is, how to create one, or why it matters for your business, this guide gives you a complete overview. We'll walk through the full FNSKU barcode process — how to find, print, and apply your labels — plus the labeling mistakes that cost sellers money and the essential differences between every Amazon barcode type.

What Is an FNSKU Barcode?

FNSKU stands for Fulfillment Network Stock Keeping Unit. It's an Amazon specific barcode assigned to every product in the Fulfillment by Amazon (FBA) program.

Here's the simple version: the FNSKU barcode is how Amazon knows that a specific unit in their warehouse belongs to you. Not another seller listing an identical item. Not a different variant or a different merchant. Your FNSKU identifies that product as yours.

Every FNSKU starts with "X00" followed by alphanumeric characters (example: X001ABC123). Amazon generates it automatically when you set up a listing for FBA. You don't purchase it from anyone or create it yourself.

The FNSKU appears on a scannable label — sometimes called FNSKU tags — that goes on each unit before you ship inventory to Amazon. Proper labeling is essential — each item label must include a barcode with quiet zones, a string identifier, and the product title and description.

Why Every Amazon Seller Needs an FNSKU

Here's the problem FNSKU labels solve: commingled inventory.

Without FNSKU labels, Amazon can pool your stock with units from other sellers who sell an identical item under one ASIN. A customer orders from your listing but receives another seller's unit.

If that unit is counterfeit, expired, or damaged, you get the negative review and the potential account suspension.

FNSKU labels keep your inventory physically separated inside Amazon fulfillment centers. When a customer buys from you, Amazon scans the FNSKU barcode to pull your specific unit, fulfill the order, and credit the sale to the right seller.

This also matters for reimbursement claims. If Amazon loses or damages your item in their facility, the FNSKU is how they trace it back to you. Without it, proving ownership gets significantly harder.

The FNSKU identifies a product as yours. For any Amazon seller, it's the difference between getting credited for your sales and having your inventory confused with someone else's stock. Every sale is credited to the right account because of this barcode.

FNSKU vs. ASIN Codes vs. UPC Barcode: The Complete Comparison

Amazon sellers and retailers deal with at least five different identifiers, and the confusion between them trips up both new and experienced businesses selling on the platform. Here's how they connect.

FNSKU (Fulfillment Network Stock Keeping Unit) — Created by Amazon automatically. Identifies a product tied to a specific seller. Only works within Amazon FBA.

ASIN (Amazon Standard Identification Number) — Created by Amazon. Identifies a product listing. Only works on Amazon. Every seller who lists that item shares one ASIN.

UPC (Universal Product Code) — Purchased from GS1 or other authorized sources. Identifies a product regardless of seller. Works in any store or online marketplace in the world.

SKU (Stock Keeping Unit) — Created by you. Your internal inventory tracking code. Only works within your business.

MSKU (Merchant Stock Keeping Unit) — Created by you. Your Amazon-specific internal tracking code. Only works within your Seller Central account.

The key difference: ASIN codes are used for product categorization and search functionality on Amazon. FNSKUs are used to track inventory and credit the right seller for each sale. Multiple sellers can share the same ASIN, but each seller gets a unique FNSKU for that product.

A UPC is a universal product code. An FNSKU only works within Amazon's fulfillment system. UPCs are purchased from GS1. FNSKUs are generated by Amazon when a seller opts to use the FBA service.

FNSKU vs. Manufacturer Barcode and UPC Labels

Some sellers wonder whether they can skip FNSKU labels and just use the UPC barcode or manufacturer barcode already on their packaging. You technically can in some categories, but you probably shouldn't.

Using your existing barcode or UPC labels means Amazon treats all units as identical, regardless of which seller shipped them. That's commingled inventory — and it opens you up to every risk described above.

Amazon requires FNSKU labels instead of existing barcodes for several categories, including consumables, topicals, and baby products. If your item doesn't have a scannable UPC or EAN, you'll also need an FNSKU.

When you apply an FNSKU label, it must completely cover any existing barcodes on the packaging. Two visible barcodes on one item creates scanning confusion and can result in your item labels being rejected.

How to Create an FNSKU in Amazon FBA

FNSKUs are automatically generated by Amazon when you add an item to the Fulfillment by Amazon program. You don't need to apply or pay for it.

Here's the step-by-step:

1. Log into Seller Central and go to your Inventory page.

2. Set your barcode preferences. Navigate to Settings → Fulfillment by Amazon → FBA product barcode preference → select "Amazon barcode."

3. Create your product listing (or convert an existing Merchant Fulfilled listing to FBA). You'll need a UPC, EAN, or GTIN exemption to create the listing if you don't already have one.

4. Amazon generates the FNSKU. This happens automatically once your listing is connected to the FBA program. No extra steps required.

Amazon will automatically assign an FNSKU to your product when you enable FBA in your listing. The FNSKU is free and shows up within minutes.

Setting Your Amazon Barcode Preferences

Your barcode preferences in Seller Central control whether Amazon uses FNSKUs or existing barcodes to track your inventory. To check or change this:

Go to Settings → Fulfillment by Amazon → FBA product barcode preference. Select "Amazon barcode" to use FNSKUs. This is the recommended setting because it keeps your inventory separated from other sellers who list an identical item.

If you select the other option, your items become eligible for commingled storage. Most experienced sellers avoid this.

How to Find Your FNSKU in Manage Inventory

To find the FNSKU for your product, go to Manage Inventory in Seller Central and check that the FNSKU column is visible in your preferences.

Click the gear icon above your inventory list. Check the box next to "FNSKU" to add that column. Your FNSKU will now appear next to each FBA listing in the table.

You can also find it by clicking into a specific product and looking at the Product Details section. The FNSKU is listed alongside your ASIN, SKU, and other identifiers on the page.

Quick tip: FNSKUs usually start with "X00" when generated by Amazon. If you're looking at a barcode on a product and it starts with X00, that's an FNSKU.

To look up what ASIN an FNSKU maps to, search the FNSKU in your Manage Inventory search bar. You can also check inventory reports at Reports → Fulfillment → Inventory.

Note: you can't look up another seller's FNSKU — each one is tied to a specific seller account.

If you use third-party inventory management tools, your FNSKUs need to be synchronized with your listings to track inventory accurately. Most tools let you import and update FNSKUs individually or in bulk.

Just make sure each product's Merchant SKU field is populated and the FNSKU is assigned in Amazon first.

How to Print and Apply Your FNSKU Label

To download your FNSKU label, go to the Manage Inventory section, find your product, and click "Print Item Labels" from the dropdown menu next to Edit.

Amazon generates a PDF with your FNSKU barcode labels. Select the label size and quantity before downloading the file.

FNSKU label requirements:

• Size: Between 1" x 2" and 2" x 3" (standard Avery 5160 sheets work at 1" x 2-5/8")
• Background: White with removable adhesive
• Barcode format: Code 128A with a minimum barcode height of 0.25 inches
• Required elements: A scannable barcode with quiet zones, a string identifier, product title, and description
• Placement: Flat surface on the packaging. Must completely cover any existing barcodes on the boxes or shrink wrap.

Your two labeling options in 2026:

1. Label products yourself. Print FNSKU labels on adhesive label sheets and apply by hand. This costs under $0.01 per unit (just label sheets and ink).

It gives you full control over quality and lets you inspect each item during the labeling process before you send inventory to Amazon.

2. Have your supplier label them. Send your supplier the FNSKU barcode PDF and have them apply the labels before shipping. This works well for private label products and large shipments where labeling thousands of units yourself isn't practical.

Important 2026 update: Starting January 1, 2026, Amazon discontinued its FBA prep and labeling services for U.S. sellers. Before this change, you could have Amazon label your products for $0.55 per unit.

If you used to have Amazon label your inventory, that option is no longer available. All sellers must now label units themselves or use a third-party prep service.

You can also use an online FNSKU barcode label maker to create compliant, professional FNSKU barcode labels if you need custom sizes or formats beyond what Seller Central provides.

FNSKU Labeling Costs for Your Amazon Business

With Amazon's labeling service discontinued, here's what FNSKU labeling costs in 2026:

DIY labeling:

• Label sheets (Avery 5160 or equivalent): ~$15 for 3,000 labels
• Printer: Use what you already have
• Cost per unit: Under $0.01
• Trade-off: Takes time, especially for large shipments

Supplier labeling:

• Most suppliers charge $0.10–$0.30 per unit
• Cost per unit: $0.10–$0.30
• Trade-off: Costs more, but saves hours on large shipments and lets you streamline the prep workflow

Third-party prep services:

• Prep centers typically charge $0.50–$1.50 per unit (includes inspection + labeling)
• Cost per unit: $0.50–$1.50
• Trade-off: Most expensive, but fully hands-off

For sellers shipping 500+ units per shipment, DIY labeling can save hundreds of dollars on a single shipment. But if your time is better spent on sourcing and sales, a supplier or prep service can make more sense for your business.

Common FNSKU Labeling Mistakes (and How to Avoid Them)

These are the mistakes that cost sellers time, money, and inventory:

1. Not fully covering the existing barcode. If the original barcode is still scannable, Amazon's system might read the wrong code. Your item gets checked in under the wrong ASIN, and tracking it down becomes a mess.

Always cover the original barcode completely with your FNSKU label.

2. Labels peeling off during shipping. This happens when sellers use regular paper and tape instead of proper adhesive label stock. Amazon will reject units with missing or unreadable labels.

Use removable adhesive labels designed for product packaging — not printer paper taped to boxes.

3. Wrinkled or smudged barcodes. A barcode that can't be scanned is useless. Print on clean, dry label stock and apply labels to flat surfaces. Avoid placing them over seams, curves, or shrink-wrap ridges where the label can't lay flat.

4. Putting the wrong FNSKU on a product. If you sell multiple products, one mislabeled unit creates an inventory tracking nightmare. The customer gets the wrong item, you get a return, and your inventory counts are off.

Check each label against the product before applying.

5. Forgetting to update FNSKU after relisting. If you delete and recreate a listing, Amazon generates a new FNSKU. Your old labels are now invalid. Always verify your FNSKU in Manage Inventory before printing a new batch of labels.

6. Using FNSKU labels on FBM orders. FNSKUs are for FBA only. If you fulfill orders yourself through Merchant Fulfilled, use your own shipping labels and barcodes. FNSKU labels on FBM shipments just create confusion at both ends.

Frequently Asked Questions

What Is the Difference Between SKU and FNSKU?

A SKU (Stock Keeping Unit) is a code you create to track your own inventory. You set the format and naming convention — it's internal to your business.

An FNSKU (Fulfillment Network Stock Keeping Unit) is a code Amazon creates to track your products inside their fulfillment centers. You need a SKU for your own records and an FNSKU for Amazon's facilities. Both can exist for the same item at the same time.

What Is an FNSKU Used For?

Amazon uses the FNSKU to identify which seller owns each unit in their facilities. When a customer places an order, Amazon scans the FNSKU barcode to pull the correct seller's product, ship the order, and credit the sale to the right account.

It prevents your inventory from being mixed with items from other sellers, even when multiple sellers list identical items.

How Do I Get an FNSKU Code From Amazon?

Create a product listing in Seller Central, set your fulfillment method to FBA, and select "Amazon barcode" in your barcode preferences. Amazon will automatically generate an FNSKU for that product.

You can then download and print item labels from the Manage Inventory page. Amazon Seller Support can help if you run into issues during this process.

Is an FNSKU the Same as an ASIN?

No. An ASIN (Amazon Standard Identification Number) identifies a product listing — it's the same for every seller who lists that product. An FNSKU identifies a specific seller's inventory of that product.

Businesses selling identical items will each have their own unique FNSKU. While ASIN codes stay the same for every seller, the FNSKU changes with each account. The ASIN connects to the product page. The FNSKU connects to the seller's inventory.

Do I Need FNSKU Labels for Every FBA Product?

Yes. Amazon requires each unit to be labeled with the FNSKU barcode if you use Amazon FBA. Products stored in Amazon fulfillment centers need to be traceable to a specific seller account.

Many categories — like consumables and baby products — specifically require an FNSKU instead of a manufacturer barcode. Even in categories where manufacturer barcodes are accepted, using FNSKU labels protects you from the commingled inventory problems that lead to negative reviews and account issues.

Can I Use FNSKU Labels Outside of Amazon?

No. FNSKU barcodes only work within Amazon's fulfillment system. For retail stores, other online marketplaces, or anywhere outside Amazon, you need a UPC barcode, EAN, or other universal product code.

Only apply FNSKU labels to products you're sending to Amazon's FBA warehouses for fulfillment.

The FNSKU is one of those things that seems confusing until you set it up once. After that, it's just part of the routine. Label every unit, keep your inventory separated, and protect your seller account from commingled inventory. Once your labels are handled, you can focus on what actually grows your Amazon business — pricing competitively, sourcing profitable products, and scaling your sales.