Should I Use an Amazon FNSKU Label?

4th May, 2025

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Understanding the Basics: Manufacturer Barcodes vs Amazon FNSKU
When sending products to Amazon FBA, you have two primary labelling options: the manufacturer barcode (usually a UPC or EAN) or Amazon's FNSKU label. While both methods are valid, the choice you make can significantly affect your inventory accuracy, customer experience and long-term business health.

The manufacturer barcode is the universal barcode printed on products by the original producer. These codes are shared across all units of the same product, regardless of who sells them. If your item is the exact same product that another seller is also sending to Amazon, both products will carry the same manufacturer barcode. That might seem efficient, but it comes with some serious caveats.

The Risks of Using Manufacturer Barcodes
Using manufacturer barcodes means that your inventory is pooled with other sellers’ stock. Amazon’s fulfilment system treats these items as interchangeable. That can be perfectly fine if every seller plays by the rules and sends in genuine, brand-new stock. But what if they don’t?

Here is where things can go wrong:

• Another seller might send in used, damaged or even counterfeit stock
• That stock gets picked and shipped to your customer
• The customer complains or requests a refund
• The negative feedback, A-to-Z claim or refund comes out of your account

In short, your reputation and revenue can suffer for mistakes you didn’t make. And that simply is not fair.

If you are an experienced seller, you may have already faced this issue without even realising it. Customer complaints, unexpected returns or damaged stock reports might be linked to this pooled inventory system. By using manufacturer barcodes, you lose control over what your customer actually receives.

Enter the FNSKU: Your Barcode for Peace of Mind
To avoid these problems, Amazon offers the FNSKU (Fulfilment Network Stock Keeping Unit). This is a barcode generated specifically for your Amazon account and listing. When you label your inventory with FNSKUs, Amazon only ships your units to your customers. You are no longer in the shared inventory pool.

In essence, the FNSKU system keeps your inventory separate and protected. Here is why it matters:

• Accountability: Only you are responsible for your products
• Accuracy: Your customers receive the exact stock you send
• Quality Control: No more worrying about rogue sellers damaging your brand
• Refund Protection: If there is an issue, it is actually related to your product—not someone else's

For wholesale and arbitrage sellers, FNSKU labelling is practically essential. It is the only way to ensure your customers get the items you sourced and packed with care. FNSKU labelling costs as little as 30p a unit, see our pricing here.

But What About Private Label Sellers?
If you are selling your own branded products, perhaps sourced from overseas or manufactured exclusively for you, then you might be thinking that manufacturer barcodes are fine. After all, no one else should have your exact product.

While that is mostly true, there are still risks. Fake sellers can hijack listings. Competitors might try to copy or resell knockoffs. If they are allowed to use manufacturer barcodes, their items could end up in your listing’s fulfilment pool.

Even as a private label seller, using FNSKU labels gives you extra protection and traceability. It ensures that only your genuine products reach your customers. Plus, if an issue ever arises, Amazon can pinpoint it back to your batch and not someone else’s mistake.

How to Use FNSKU Labelling Effectively
Implementing FNSKU labelling is easier than you might think. When you create a shipment in Seller Central, you will be asked whether you want Amazon to label your products or if you will do it yourself.

If you choose to label your inventory, simply download the FNSKU labels during the shipment creation process. Then print and apply one label to each unit. These labels must completely cover the original manufacturer's barcode.

Alternatively, you can work with a prep centre like Express Prep. We specialise in applying FNSKU labels accurately for your business. Whether you are shipping 50 units or 5000, we ensure everything is labelled to Amazon’s standards.

A quick tip: Always check the label requirements for your product category. Some require additional labels like suffocation warnings or expiry dates.

Are There Any Downsides to Using FNSKU Labels?
There are some added steps when using FNSKU barcodes. You need to print and apply them, or pay Amazon or a prep centre to do it. That adds cost and time. However, the benefits of control, accuracy and brand protection far outweigh these minor downsides.

If you are building a long-term business on Amazon, you need systems that scale and protect your reputation. FNSKU labelling is a small investment that prevents major headaches down the line.

Conclusion: So, Should You Use FNSKU Labels?
Yes, almost always.

Unless you are a private label seller with airtight control of your listing and zero risk of competition, FNSKU labels offer much-needed protection and peace of mind. For wholesale and arbitrage sellers, they are non-negotiable.

By using FNSKU barcodes, you keep your inventory clean, your brand safe and your customers happy. It is a smart, proactive move that can save your Amazon account from damage caused by someone else’s poor practices.

And the best part? You do not have to do it alone. At Express Prep, we label thousands of units every day. We know the rules, follow Amazon’s standards and keep your inventory compliant and safe.

Book a free call with one of our team at Express Prep to make your fulfilment easier and give you your time back. 

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