What is a seller SKU on Amazon?

SKU stands for stock keeping unit. On Amazon, the seller SKU (also called merchant SKU or MSKU) is the code you pick for your own offer on an ASIN. It can be up to 40 characters and must be unique within your seller account.

Amazon uses the SKU to know which of your offers you mean. When you change a price, update stock, or switch fulfillment, you do it for a SKU.

SKU vs ASIN vs FNSKU

• ASIN identifies the product and its shared detail page. Every seller of the product uses the same ASIN.
• Seller SKU identifies your offer on that ASIN. You can have several SKUs on one ASIN, for example one fulfilled by Amazon and one you ship yourself, or a new and a used offer.
• FNSKU is the label code Amazon uses to identify your units in its warehouses when you use FBA. It often starts with X00.

Where to find your SKU

In Seller Central, open Inventory → Manage All Inventory. The SKU is shown next to each product, along with the ASIN. The same SKU appears in inventory reports and in order details.

Why SKUs matter for repricing

Prices on Amazon belong to offers, so a repricer must change the price of a specific SKU. If you sell the same ASIN through FBA and FBM, each offer has its own SKU and its own price, and you choose which one to reprice.

In AMZTarget Repricer you enter the seller SKU for the offer you want to change. Price updates are then sent through Amazon's official SP-API for that SKU only, within the minimum and maximum bounds you set.

FAQ

Can I change a SKU after the offer is created?

Not directly. A SKU is fixed once the offer exists. To use a new code, you create a new offer with the new SKU and close the old one.

Do I need a SKU to track a product?

No. Rank tracking and listing monitoring work with the ASIN and marketplace. A SKU is only needed for actions on your own offer, such as repricing.

Is the SKU visible to shoppers?

No. Shoppers see the ASIN in product details, but the seller SKU stays in your account, reports, and API calls.