A Seller's Guide to Amazon FBA Labels (FNSKU, Shipping, Box)

Alright, Let’s Have a Little Chat About Amazon FBA…

Look, if you're selling on Amazon, you’ve chosen to play in the big leagues. And in the big leagues, they don't screw around. You’re playing in Jeff Bezos' sandbox, and you have to play by his rules. And let me tell you, after 5 years of dealing with Seller Central on both sides of the planet—from dusty warehouses in Bhiwandi, India, to massive fulfillment centers in California—the fastest way to get your inventory rejected, your shipment delayed for weeks, or even your account suspended is by messing up one tiny, seemingly insignificant thing: your labels.

Seriously. People pour thousands of dollars into product sourcing, PPC campaigns, and fancy photography, and then they slap on a blurry, misaligned, or incorrect FBA label and wonder why their business is failing. It’s like building a Ferrari and then putting bicycle tires on it. According to a 2024 report by ShipMatrix, labeling errors account for over 25% of all inbound shipment problems at major fulfillment networks like Amazon. That's a quarter of all problems, just because of a stupid sticker!

This isn't going to be some corporate-speak guide regurgitated from Amazon's help pages. This is the real, raw, 'I-once-lost-$1,200-on-a-single-shipment-because-of-a-smudged-barcode' guide. I’m going to tell you exactly what you need to know about Amazon FBA labels for both the US and Indian markets, what mistakes will get you in hot water, and how to do it right, for free, every single time.

The Three FBA Labels That Will Make or Break Your Business

First thing's first. When we talk about 'FBA labels', we're not talking about one thing. We're talking about a holy trinity of stickers. You have to get all three right. Messing up even one can derail your entire operation.

1. The FNSKU Label (The Product ID): This is the most important one. FNSKU stands for Fulfillment Network Stock Keeping Unit. It’s Amazon's internal barcode for your specific product. When you list a product, Amazon generates this code. It starts with 'X00...'. This is how Amazon knows that the specific unit of 'Super-Duper Face Cream' on their shelf belongs to you, and not the ten other guys selling the exact same cream.
2. The Shipping Label (The Box's Passport): This is the big label that goes on the outside of your master carton—the big box you send to the Amazon warehouse. It has the Amazon warehouse address, your return address, and a big barcode that tells the warehouse, 'This box is part of Shipment ID FBA12345XYZ.' This is how they check in your shipment.
3. The Box Label (The Carton Contents): This is a smaller label that also goes on the outside of the master carton, usually next to the shipping label. It tells the warehouse what's inside the box, either in terms of mixed SKUs or single-SKU contents.

Think of it like this: The Shipping Label gets the box to the right building. The Box Label tells them what to expect inside. And the FNSKU Label identifies every single item once they open it.

Part 1: The FNSKU Label – Your Product’s Fingerprint

This is where most new sellers screw up. They think they can just use the regular barcode that came on their product (the UPC or EAN). BIG MISTAKE. Unless you’ve gone through the complex process of brand registry and commingling your inventory (which is a terrible idea for 99% of sellers, trust me), you MUST cover the original barcode with your unique FNSKU label.

Personal Horror Story #1: The Commingling Catastrophe (USA, 2018). Back when I was young and naive, I thought commingling was a great idea. It means you don't have to print FNSKU labels; you just use the product's UPC. Amazon then lumps your inventory in with every other seller's inventory of that same product. It's faster, right? Wrong. I was selling a popular brand of kitchen gadget. Another seller sent in a batch of cheap, counterfeit versions of the same product. A customer ordered from my listing but got shipped one of the fake ones from the shared inventory pool. I got the 1-star review, the 'inauthentic item' complaint, and a 72-hour account suspension notice. I had to write a humiliating 'Plan of Action' to Amazon, swearing I'd never commingle again. It was a $2,000 lesson in why you ALWAYS use your FNSKU. It's your only proof that the unit is yours.

FNSKU Label Requirements (Non-Negotiable):

• Format: Must include the FNSKU barcode (starts with X00), the product title (truncated is fine), and the item condition (e.g., 'New').
• Size: No specific size is mandatory, but it needs to be big enough to be easily scannable. Common sizes are 1" x 2.625" in the US or 38mm x 25mm in India. The key is that it's readable.
• Placement: It MUST completely cover any other scannable barcode on the product. No part of the original UPC should be visible. Place it on a flat, smooth surface. Don't wrap it around a corner.
• Print Quality: It has to be printed in black ink on a white, non-reflective label. No smudges, no fading, no 'toner-saver' mode. A blurry barcode is a dead barcode. Amazon’s official guidelines on this are very clear, as you can see on their FNSKU Label Requirements page.

How to Actually Print FNSKU Labels:

When you create your shipping plan in Seller Central, Amazon gives you a PDF of your FNSKU labels. You have a few options:

1. Let Amazon Do It (The Expensive, Easy Way): Amazon offers an 'FBA Label Service' for a per-item fee (around $0.55 in the US, ₹10-15 in India). For a new seller sending in 20 items, this is a no-brainer. Let them do it. For a seller sending in 500 items, this is financial suicide.
2. Print on A4/Letter Sheets (The Starter Method): Amazon lets you choose a template that matches common sticker sheets (like Avery 5160 in the US). You print the PDF on your regular inkjet/laser printer. It works, but it's slow, and aligning the sheets can be a pain.
3. The Pro Method (Thermal Printer): This is the way. A thermal printer spits out individual, peel-and-stick labels in a second. To do this, you can't use Amazon's default PDF. You need to take the FNSKU number itself and use a third-party tool to generate a PDF formatted for your 1-up thermal labels. There are many tools for this, including free options like the ones on SmartLabelPrint. It adds one extra step but saves you an eternity of time. I cover the printer differences in-depth in my printer comparison guide.

Part 2: The Shipping & Box Labels – Your Carton’s ID

Okay, your individual products are all labeled up. Now you put them in a big master carton to send to the fulfillment center. This carton needs its own set of labels.

Personal Horror Story #2: The Lost Shipment (India, 2021). During the monsoon season in Mumbai, I was sending a shipment to the Bhiwandi (BOM5) FC. I was using a cheap laser printer, and the toner was running low. The shipping label barcode looked a little faded, but I thought, 'Eh, it's probably fine.' It wasn't. The label got wet in transit, the already-faded barcode smudged, and the box became unscannable. It sat in a corner of the Delhivery hub for three weeks marked as 'Unidentified'. It was a huge issue to get them to find it, and I missed a huge sales spike for that product. Lesson learned: print quality is not optional.

Shipping & Box Label Requirements:

• How Many?: You need ONE of each (one shipping label, one box label) on every single carton you send.
• Placement is CRITICAL: Place both labels on a flat side of the box, not on a seam or corner where it might get ripped or creased. Put them next to each other. Do NOT put them on the top or bottom of the box, as they can get covered by other boxes during transit.
• Size: The standard size is 4x6 inches. Amazon generates them in a PDF, often two on a single A4/Letter page.
• DO NOT Obstruct: Make sure your tape doesn't cover any part of the barcodes or addresses. A single piece of glossy tape can reflect a scanner's laser and make the barcode unreadable.
• Cover Old Labels: If you're reusing a box (which is fine!), you must completely obliterate any old shipping labels, barcodes, or addresses. I use a black permanent marker or a blank 'cover-up' label. A confused sorting machine is your worst enemy. Check out Amazon's official Shipment Label Requirements for the nitty-gritty details.

How to Actually Print Shipping & Box Labels:

This is where a thermal printer really shines. Amazon's PDF often puts two 4x6 labels on one A4 page. Trying to print this on a thermal printer is a disaster.

1. The Free Way (Recommended): Use a free online PDF cropping tool. Upload Amazon’s PDF, draw a box around the first 4x6 label, and the tool will split the PDF into individual 4x6 pages. Now you can print this new PDF directly to your thermal printer.
2. The A4 Sheet Way: If you're still on an inkjet/laser, you can buy A4/Letter sheets that are pre-cut into two large labels. Print the PDF on these, and you're good to go.

The Ultimate FBA Labeling Checklist – Don't Ship Without This

Seriously, print this out and tape it to your packing station until it becomes muscle memory.

• FNSKU Labels: Is the original product barcode (UPC/EAN) COMPLETELY covered?
• FNSKU Labels: Is the FNSKU label flat, not wrapped around a corner?
• FNSKU Labels: Is the print dark, crisp, and totally free of smudges?
• Carton Labels: Are there exactly ONE shipping label and ONE box label on the carton?
• Carton Labels: Are they on the side of the box, not the top/bottom seam?
• Carton Labels: Is there ZERO tape over any barcodes or text?
• Carton Labels: Have all old labels on the box been completely removed or blacked out?
• Printer Settings: Did you print at 100% scale ('Actual Size')? Double-check this. I'm serious.

Conclusion: It’s Not Sexy, But It’s Your Business’s Lifeline

Look, nobody gets into e-commerce because they have a burning passion for printing labels. It's the most boring, unglamorous part of the job. But it's also the foundation upon which your entire logistics operation is built. Getting it right costs you nothing but a bit of attention to detail. Getting it wrong can cost you thousands of dollars in lost inventory, chargeback fees, and account health nightmares.

Follow the rules. Use the right tools (even the free ones). Don't cut corners. Your future self, swimming in profits instead of dealing with Seller Support cases, will thank you. For more detailed guides on other label types, check out our other posts on general shipping labels and how to print 4x6 labels without a thermal printer.