SKU (Stock Keeping Unit)
Last updated: March 17, 2026
SKU defined: What the acronym stands for
The abbreviation SKU stands for Stock Keeping Unit. So what is a SKU? It is an alphanumeric code, typically made up of 8 to 12 characters, used to uniquely identify a single product or product variant. Unlike universal codes such as EAN or UPC, the SKU number is created and assigned by the seller itself.
SKUs are an indispensable tool for inventory management. The SKU meaning goes beyond a simple label: they let sellers track stock precisely, analyze sales, and plan reorders efficiently. Especially with a large assortment featuring many variants (sizes, colors, configurations), SKUs bring order and transparency.
Table of contents
Structuring a SKU: Best practices
A well-structured SKU should convey information about the product at a glance. There are no fixed rules, but proven practices help you establish a consistent system.
Example of a SKU structure:
CAT-PROD-VAR-SIZE
e.g. ELEC-HDPH-BLK-L = Electronics, Headphones, Black, Large
Recommendations for creating SKUs:
- Start with the category or brand
- Add a product identifier
- Append variants such as color, size, or material
- Avoid special characters and spaces
- Keep the SKU as short as possible, but as long as necessary
SKU vs. ASIN vs. EAN: The differences
In the e-commerce world there are several product identifiers that are often confused. Here is a clear distinction:
SKU (Stock Keeping Unit)
Created by the seller itself, used internally, with no fixed length or format. Each seller can have its own SKUs for the same product.
ASIN (Amazon Standard Identification Number)
A 10-character alphanumeric code, assigned by Amazon, that uniquely identifies a product on the Amazon marketplace.
International product codes (12-13 digits), assigned by GS1, globally unique and valid across all sales channels.
SKU on Amazon: Merchant SKU explained
On Amazon, the SKU is referred to as the Merchant SKU or Seller SKU. It is a mandatory field when creating a new product listing and is used to manage your offers internally within Seller Central.
Important to know: Amazon automatically generates a SKU if you don't provide your own. However, it is strongly recommended that you use your own SKUs, because the automatically generated codes are hard to remember and manage.
Practical tip:
If you work across multiple marketplaces or in different systems (ERP, inventory management), you should use the same SKU everywhere. That makes synchronization easier and prevents errors in stock management.
Benefits of a solid SKU structure
A well-thought-out SKU system brings numerous benefits to your Amazon business:
- Better inventory overview: Quickly recognize products and variants
- More efficient reordering: Easy identification of products with your supplier
- Simplified analysis: Grouping products for sales evaluations
- Error reduction: Fewer mix-ups during picking and shipping
- Multi-channel compatibility: The same SKU is usable across all sales channels
Frequently asked questions (FAQ)
Can I change my SKU on Amazon after the fact?
No, once a SKU has been assigned it cannot be changed on Amazon. If you want to use a different SKU, you have to delete the listing and create a new one with the desired SKU. Keep in mind that any existing FBA inventory remains linked to the old SKU.
How long can a SKU be on Amazon?
Amazon allows SKUs of up to 40 characters. However, it is recommended that you keep SKUs between 8 and 12 characters to make them practical and readable. Letters, numbers, and a few special characters such as hyphens are permitted.
What is the difference between SKU and FNSKU?
The SKU is your internal product code that you assign yourself. The FNSKU (Fulfillment Network SKU), on the other hand, is generated by Amazon and uniquely links a product to you as the seller. The FNSKU is applied as a barcode on FBA products and is important for the Amazon warehouse.
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