An Amazon SKU is a merchant-defined identifier that a seller assigns to every unique product variant they list on Amazon. Unlike an ASIN, which Amazon controls, the SKU is created and owned by the seller and can follow any naming convention. It ties a Seller Central listing to the seller’s own inventory, purchase orders and accounting records. That is why one physical product usually has a single ASIN but a different SKU for every seller offering it.
Why It Matters for Sellers
The SKU is the anchor that connects Amazon inventory to a seller’s back office. Every FBA shipment, replenishment report, storage fee and profit calculation is grouped by SKU.
A messy SKU scheme causes real damage. Reused SKUs make reconciliation painful. So do SKUs that encode nothing about brand, size, colour or pack quantity, and both leave stranded inventory when Amazon’s catalogue and the seller’s ERP disagree. A disciplined convention makes it easy to spot duplicated listings, retire dead variants and audit margin at the variant level.
Where to Find Your SKU in Seller Central
Amazon’s own guidance is short: from the main menu choose Inventory, then Manage All Inventory, and the Manage Inventory page lists every active product SKU (Amazon, SKU definition guide). The same identifier appears as item_sku in flat files and inventory reports, which is why sellers often meet it under two different names.
Can a SKU Be Changed?
Treat it as permanent. Amazon states that existing SKUs remain unchanged unless the product is deleted. There is no rename in place.
Retiring a SKU means removing the listing and creating a new one, and the sales history stays with the old identifier. That is the practical reason never to recycle a retired SKU on a different product.
How to Structure a SKU
Amazon says SKUs are usually made up of 8 to 10 letters and numbers, and sets no naming rules beyond that. The patterns that survive an audit share a few traits:
- Encode brand or supplier code in the first segment, for example ACME.
- Encode product family and variant attributes (colour, size, pack) in short codes.
- Keep a permanent, non-reusable serial, and never recycle a retired SKU on a new product.
- Avoid spaces and special characters that break flat files or CSV uploads.
Example: ACME-TSHIRT-BLK-L-2PK is easier to audit than sku0042. The first tells you brand, product, colour, size and pack quantity without opening a report; the second tells you nothing.
SKU vs ASIN vs FNSKU
| Identifier | Assigned By | Scope | Format |
|---|---|---|---|
| SKU | Seller | Per seller, per variant | Alphanumeric, typically 8 to 10 characters |
| ASIN | Amazon | One per product across the whole catalogue | 10-character alphanumeric |
| FNSKU | Amazon (FBA only) | Per seller, per ASIN, inside FBA | Starts with X, 10 characters total |
The same t-shirt has one ASIN, but ten sellers offering it have ten different SKUs. When that t-shirt enters FBA, Amazon issues a per-seller FNSKU that gets printed on the physical unit label. Buyers never search by SKU; they search by ASIN, keyword or title.
How SellerSonar Helps
SellerSonar Product Monitoring watches every ASIN in your catalogue, and Retail Issues Alerts surface the catalogue mismatches that cause suppressions.
Start your free SellerSonar trial today.
Related Terms
- ASIN, Amazon’s internal 10-character product ID
- FNSKU, the FBA-specific unit label Amazon assigns per seller
- Amazon FBA, the fulfillment program that generates FNSKUs from your SKUs