aia assets

Back to

UPC codes, FNKSU’s, and SKUs: Mastering Inventory Management

November 26, 2022
mastering inventory management for amazon sellers

We have talked about best practices in listing optimization and some shortcuts to streamline the process of uploading listings. But we can’t talk about inventory management without deciphering SKU, UPC, and FNSKU codes – if these are all just Greek to you, then you’ve come to the right place. Time to decode!

Amazon sellers will need to use all three codes for EACH PRODUCT!

upc, sku, fnsku, aia assets

Generating Bar Codes

UPCs (Universal Product Codes) are numeric barcodes assigned by manufacturers. UPCs are unique identifiers of the manufacturer and the exact item. If you are a manufacturer, and selling your own branded product, you will need to purchase UPC codes from GS1 (Global Standards 1). Each item (that varies in style, color, shape, etc.) will need its own barcode.

Sellers need UPCs to list their items on Amazon. These codes identify each product. UPCs do not need to BE physically on the item you’re selling but will be LISTED on the item’s detail page. Multiple sellers of identical items will be using the same UPC codes.

SKUs (Stock keeping units) can be any unique alphanumeric string assigned to each product by the seller (up to 40 characters). The Amazon SKU number is only visible in your Seller Central account and is mandatory for both FBM and FBA sellers.

You can choose your SKU number, based on size, color, purchase location, style, etc. It is a seller’s internal way of keeping track of their inventory

FNSKU (Fulfilment Network Stock Keeping Units) are Amazon-specific barcodes. Used ONLY by FBA sellers, the FNSKU identifies sellers’ products and connects those products to your Amazon Seller account.

An FNSKU must be affixed to each product and can be downloaded from your inventory dashboard.

Mastering Inventory Management

Now that we have defined the importance of the different bar codes, let’s dive into the importance of inventory management. Keeping your store well-stocked is a key marker of success on Amazon. Utilizing inventory management tools is crucial to your success. They can help you determine when to restock items, make rapid pricing changes, or run promotions to increase sales and improve turnover. Many add-ons, APIs, and external inventory management tools are effective. Find the best one that works for you and your team.

Consequences of Going Out of Stock

  1. The decline in sales revenue
  2. Loss of momentum
  3. Customers will shop your competition
  4. Drop in your keyword and category ranking
  5. Lost organic search visibility

If your bestselling product goes out of stock – even if your PPC is doing great, your ranking high, and reviews are top-notch – your product will tank, and recovery will be challenging.

What if you have TOO much inventory?

  1. Increased warehouse costs
  2. Potential damage to stale inventory
  3. Spoilage
  4. Shifts in customer demands may make inventory unsellable
  5. Limits Cash Flow







Now that you’ve mastered the Amazon dashboard, and are an expert at listing products, it’s important for your business to grow and develop. What’s a better model for your business – FBA or FBM? Let us know, and we’ll talk about it next time!

Ready To Buy an Amazon Seller Account?