For decades, stock-keeping units, or SKUs, have been assigned to individual products for inventory purposes. If you’ve ever worked in retail, you probably remember SKUs as the barcodes you scanned for customers at the register. Those barcodes also have a number printed along with the code, usually six to eight digits in length. If for some reason the barcode doesn’t scan, employees can manually input the numbers into the cash register. SKUs are used not only for tracking in-store inventory, but also for streamlining the checkout process and detecting product theft.

Finding the SKU Number on Products

A barcode is a series of black vertical lines equal in length. Below this code is a number for manual entry. If you don’t see the barcode right away, continue to search; sometimes it's placed in an obscure location, such as the underside of a box or on the inside flap. However, there are some cases where the barcode plays a not-so-fun game of hide-and-seek. For items like clothing and toys, the SKU is often located on the price tag, which is either attached by a plastic fastener, sewn into the product or affixed to the surface of the item on a sticker. If you’ve searched exhaustively and still haven’t found the barcode, it’s possible the item hasn’t been assigned one. If you’re in a store, the SKU could also be posted on the shelf where the item was displayed, rather than on the product itself.

Locating the SKU on a Website

As online shopping has become more prevalent, businesses have begun to attach the SKU item number to the products posted on their websites. You can find the number listed with the product as "SKU," likely without any evidence of a barcode. However, some businesses opt to track items by manufacturer part number or some other identifier, since they may not be using a barcode scanner to manage their inventory. Amazon's fulfillment service, for instance, uses both manufacturer barcodes and its own barcode, called an FNSKU, for order pickers in its warehouses.

When There Is No SKU

In some cases, a retailer will use the SKU only internally, not displaying it anywhere for customers to use. In that case, only employees may use SKUs to scan items before shipping, a process that helps with inventory tracking. When the item arrives in the mail, however, the customer may still be able to see the barcode and number attached to the product on a sticker. If not, the barcode may be printed on the customer's receipt.