Amazon FBA Labeling Requirements: FNSKU, Barcodes, and Shipment Labels
Incorrect labeling is one of the most common reasons Amazon FBA shipments get rejected or stranded at fulfillment centers. Understanding Amazon FBA labeling requirements before you print your first shipment saves you money, time, and frustration.
Two Types of Labels You Need
Amazon FBA requires two distinct types of labels:
- Unit labels (FNSKU): Applied to each individual product unit
- Shipment/box labels: Applied to each shipping carton
Both are mandatory. Missing either will result in your shipment being received incorrectly or rejected.
FNSKU Labels: The Unit Barcode
What Is an FNSKU?
FNSKU stands for Fulfillment Network Stock Keeping Unit. It’s Amazon’s proprietary barcode that uniquely identifies your product listing. Unlike a UPC (which identifies a product universally), the FNSKU ties inventory to your specific seller account.
When Amazon scans an FNSKU at intake, it knows exactly which seller’s inventory this unit belongs to and which listing it should be connected to.
FNSKU Label Specifications
- Size: Minimum 1″ × 2″ (recommended: 1″ × 2.625″ — standard address label size)
- Print quality: 300 DPI minimum; must scan reliably from 2 feet
- Format: Code 128 barcode with human-readable FNSKU number below
- Background: White label with black barcode
- Color: No colored background that interferes with scanning
FNSKU Label Placement Rules
- Must cover (or replace) the manufacturer barcode (UPC/EAN) entirely — Amazon cannot have competing barcodes on a unit
- Must be flat — no bubbles, wrinkles, or folds crossing the barcode
- Must be placed on the flat surface of the product, not on shrink wrap or curved surfaces
- For poly-bagged items: label goes on the outside of the bag
- For items in boxes: label goes on the outside of the box
Where to Get Your FNSKU
In Seller Central: Inventory → Manage All Inventory → Select product → Print Item Labels. You can download the FNSKU as a PDF in standard label sizes (Avery 5160 format). Print on standard address labels or have your supplier apply them during production.
Barcode Requirements: UPC vs FNSKU vs Manufacturer Barcode
Amazon allows three barcode options for identifying units:
- Manufacturer barcode (UPC/EAN): Only usable if you’re enrolled in Amazon’s “Stickerless, Commingled Inventory” program — not recommended as it commingles your inventory with other sellers’ identical products
- FNSKU label: Applied over the manufacturer barcode; keeps your inventory separate (recommended)
- Transparency codes: For brand-protected ASINs; an additional layer of anti-counterfeiting
For most sellers, applying your FNSKU label over the manufacturer barcode is the right choice. It keeps your inventory segregated, which means any returns come back to your account only.
Shipment Box Label Requirements
Each shipping carton sent to Amazon requires a box label generated in Seller Central during the shipment creation process.
Box Label Specs
- Size: Minimum 3.3″ × 4.7″
- Placement: One label per box, on the largest flat side
- Visibility: Must be fully visible and not obscured by tape, straps, or other labels
- Contents: FBA shipment ID, Amazon destination warehouse code, your name, and a scannable barcode
Do not apply your box label until you’ve finalized the shipment in Seller Central — the label includes warehouse routing information that determines where Amazon sends your box.
Suffocation Warning Label
Required on all poly bags with an opening of 5″ or larger:
“WARNING: To avoid danger of suffocation, keep this bag away from babies and children. Do not use this bag in cribs, beds, carriages, or playpens.”
Minimum 10-point font. Can be printed directly on the bag or applied as a sticker.
Expiration Date Labels
For consumables, supplements, grocery, and health items:
- Format: MM-YYYY (not day/month/year)
- Minimum font size: 36-point
- Must be on the unit itself AND the master carton
- Must be on the exterior — not hidden under flaps or inside packaging
Set / Bundle Labels
For multipacks or bundles:
- Apply “Sold as Set — Do Not Separate” label on the outside of the bundle packaging
- Each bundle gets one FNSKU (not one per component)
- The FNSKU must correspond to the bundle ASIN, not any individual component ASIN
Labeling at Factory vs FBA Prep Service vs Self-Labeling
| Method | Cost | Best For |
|---|---|---|
| Factory labeling | Usually free or ~$0.03/unit | Private label sellers with consistent orders |
| FBA prep service | $0.15–$0.50/unit | Sellers who can’t control factory output or need US inspection |
| Amazon labeling service | $0.55/unit (2025 rate) | Convenience, small volumes |
| Self-labeling | $0 (your time) | Retail arbitrage, small batches |
Common Labeling Mistakes to Avoid
- Using the wrong FNSKU (from a different variation or ASIN)
- Label wrinkles or folds across barcode
- Applying label on curved surface
- Not covering the manufacturer barcode
- Using wrong label size (too small to scan reliably)
- Printing at low DPI (blurry barcode)
- Applying box label before finalizing shipment (routing code may change)
Before your first shipment, print a test label and scan it with Amazon’s Scan & Label tool or any barcode scanner app to verify scannability.
Related Articles
- Amazon FBA Packaging Requirements: Complete Guide for 2025
- Amazon FBA Shipping Requirements: Sending Inventory to Amazon (2025)
- Amazon FBA Prep Service: What It Is and When You Need One
- Amazon FBA Step by Step Guide for New Sellers (2025)
- Amazon FBA for Beginners: Everything You Need to Start in 2025
