FNSKU Labels Explained: What They Are and How to Print Them
What is an FNSKU label, how is it different from a UPC, what size does it need to be, and how do you print FNSKU labels for Amazon FBA? Everything explained simply.
If you sell on Amazon FBA, you've probably come across the term FNSKU and wondered what it actually is, why it's different from a regular barcode, and whether you actually need it.
This post explains it simply — no jargon, no Amazon seller lingo — and shows you exactly how to get and print FNSKU labels.
What Is an FNSKU?#
FNSKU stands for Fulfillment Network Stock Keeping Unit.
It's a barcode that Amazon creates specifically for your seller account and your product listing. No other seller has the same FNSKU — even if they're selling the exact same product.
Amazon uses the FNSKU to track which units in their warehouse belong to which seller. When a customer orders your product, Amazon scans the FNSKU to make sure they pick your unit — not someone else's.
FNSKU vs UPC — What's the Difference?#
| UPC/EAN | FNSKU | |
|---|---|---|
| Created by | The manufacturer or brand | Amazon, for your seller account |
| Who uses it | Any retailer, globally | Amazon FBA only |
| Shared with other sellers | Yes (same product = same UPC) | No — unique to your account |
| Risk of inventory mixing | Yes (commingling) | No |
| Free to get | No (UPC registration costs money) | Yes (free from Amazon) |
| Where to print it | Yourself or manufacturer | Seller Central or yourself |
The key difference: a UPC identifies the product. An FNSKU identifies the product and the seller.
Do You Actually Need FNSKU Labels?#
You need FNSKU labels if:
- You're sending products to Amazon FBA (required for most categories)
- You want to make sure your inventory stays separate from other sellers
- Your product doesn't have a UPC, or you're selling used/refurbished items
You might not need them if:
- You're enrolled in Amazon's Commingling program (where Amazon mixes your inventory with other sellers of the same product) — rare and generally not recommended
For most FBA sellers, applying FNSKU labels to every unit is the safest approach.
What Does an FNSKU Label Look Like?#
An FNSKU label contains:
- The FNSKU code (starts with "X00" for most sellers — e.g., X001ABC2DE)
- A barcode (Code 128 format)
- The product title (often truncated)
- Sometimes the condition (New, Used - Like New, etc.)
Amazon's system generates this automatically. You can also design a custom version with clearer text or your brand name.
What Size Does an FNSKU Label Need to Be?#
Amazon's requirements:
- Minimum size: 1" × 2" (25mm × 50mm)
- Recommended size: 1" × 2.625" — this is the standard Avery 5160 label size (30 per sheet)
- Background: White or very light — colored labels cause scanning failures
- Placement: On the outside of the product, not covering the original manufacturer barcode
Most FBA sellers use 1" × 2.625" adhesive labels. A sheet of 30 costs very little, and you can print from any home printer.
How to Get Your FNSKU Code from Amazon#
- Go to Amazon Seller Central → Manage Inventory
- Find the product you want to label
- Click Edit → Print Item Labels
- Set the label type, size, and number of labels
- Download the PDF and print
Amazon generates the label design for you. This is the easiest option if you just need standard labels quickly.
How to Print Custom FNSKU Labels (With Your Own Design)#
If you want a cleaner layout, bigger text, or your brand name on the label alongside the FNSKU barcode, you can design it yourself.
Step 1 — Export your FNSKU codes
In Seller Central, go to Reports → Inventory Reports and download your inventory. The report includes the FNSKU code for each ASIN.
Step 2 — Open Labeliy and choose the Inventory Label template
Go to labeliy.com/label-maker. Select the Inventory Label template — it has item name, SKU, and a barcode field.
Step 3 — Set up dynamic fields
Check the Dynamic checkbox on the item name and barcode elements. These will pull values from your spreadsheet for each product.
Step 4 — Paste your product data
Paste your product list (product name + FNSKU code) into the data table. Each row becomes one unique label.
Step 5 — Select 1" × 2.625" sheet and print
Choose a 30-up label sheet to match the standard FBA label size. Download the PDF and print on your adhesive label sheets.
How Many FNSKU Labels Do You Need?#
One per unit. If you're sending 200 units of one product, you need 200 FNSKU labels — each applied individually to each unit.
Amazon counts and scans individual units at the receiving station. A label on the outer box is not enough.
Can One FNSKU Cover Multiple Sizes or Colors?#
No. Each variation gets its own FNSKU.
If you sell a T-shirt in small, medium, and large, each size has a separate ASIN — and therefore a separate FNSKU. Same for color variations listed as separate ASINs.
Common FNSKU Label Problems#
"My FNSKU starts with B00 or X00 — which is correct?" Both are valid. B00 is older format, X00 is newer. Both work fine at Amazon fulfillment centers.
"Amazon says my label is unscannable — what went wrong?" Most common causes: label printed too small, colored label paper, barcode printed at low resolution, or label placed under tape or on a curved surface.
"Do I need to cover the original UPC?" If the product has an existing UPC, you have two options: apply the FNSKU label directly over it, or apply it in a blank area. Never leave both barcodes visible — Amazon should only scan the FNSKU.
"Can I use the same FNSKU label forever?" Yes, the FNSKU for a given ASIN doesn't change. Once you design and print the label, you can reprint it for future shipments without changes.
FNSKU labels are a simple requirement once you understand what they are. Get the code from Seller Central, print on standard 1" × 2.625" adhesive sheets, and stick one on every unit before you ship.