--- title: "What Is a SKU (Stock Keeping Unit)?" url: https://www.uncap.com/glossary/sku author: "Denis Dyli" published: 2026-10-11 updated: 2026-10-11 summary: "A SKU (stock keeping unit) is a code a business creates to identify each product and variant it stocks, so it can track inventory and report on sales. Unlike a GTIN or UPC, which GS1 issues and every trading partner shares, a SKU is internal: two sellers can stock the same item under different SKUs." --- # What Is a SKU (Stock Keeping Unit)? > A SKU (stock keeping unit) is a code a business creates to identify each product and variant it stocks, so it can track inventory and report on sales. Unlike a GTIN or UPC, which GS1 issues and every trading partner shares, a SKU is internal: two sellers can stock the same item under different SKUs. **SKU (stock keeping unit)**: A SKU (stock keeping unit) is a code a business creates to identify each product and variant it stocks, so it can track inventory and report on sales. Unlike a GTIN or UPC, which GS1 issues and every trading partner shares, a SKU is internal: two sellers can stock the same item under different SKUs. ## How it works You design your own SKU format, and one approach is to encode product attributes in the code itself. In Shopify's own example, an apparel SKU of 4225-776-3234 stands for brand 4225, leg style 776 and size 32x34. Shopify's guidelines for a format that holds up: - Characters. All numbers, or numbers and letters. Avoid formats where 0 and 1 can be confused with O and I, and skip special characters, symbols and spaces, which cause search problems. Dashes and underscores separate attributes. - Length. As short as possible, no more than 16 characters. Some catalogs work with 4 to 8. - Consistency. Every letter and number has a purpose, and an abbreviation means the same thing everywhere: if BLK means black on one product, it means black on all of them. - Uniqueness. No two variants share a SKU. A shirt in 3 sizes and 4 colors needs 12 SKUs. - Room to grow. A format built for 100 products should not run out of combinations at 1,000. SKUs are case sensitive in Shopify, so ABC123 and abc123 are two different SKUs. Across warehouses, keep one SKU per variant and track stock levels separately for each location. ## SKU vs. UPC and GTIN A GTIN (the number a UPC barcode encodes) is a universal, permanent number issued only by GS1, and every retailer, distributor and marketplace uses the same one for a product. A SKU is a flexible code you create to track your own inventory. GS1 US puts it simply: several retailers can sell the same item under the same GTIN, and each will give it a different SKU. The two work side by side: a product can carry both a SKU and a barcode, each in its own field. ## Example A distributor sells work gloves in 3 sizes and 2 colors, each as a single pair and as a box of 12 pairs. That is 3 x 2 x 2 = 12 variants, so 12 SKUs. - GLV-BLK-L-EA: black, large, single pair - GLV-BLK-L-12: black, large, box of 12 Each code is 12 characters, uses dashes between attributes, and keeps the same abbreviation for black across the line. A buyer's order for 5 boxes of GLV-BLK-L-12 is 5 x 12 = 60 pairs, picked as 5 boxes. ## On Shopify SKUs are optional in Shopify and live in the Inventory section of each product or variant, next to its barcodes. For accurate tracking and sales reporting, each SKU needs to be unique, and Shopify shows a warning when it detects a duplicate. You can edit SKUs in bulk with the bulk editor or a CSV import. Staff can search by SKU in the admin search bar and in Shopify POS, which also finds products by any of their barcodes. In the GraphQL Admin API, sku is a field on the ProductVariant object, described as a case-sensitive identifier for the variant in the shop that is required to connect to a fulfillment service. When third-party apps have sync issues, Shopify says the most likely cause is SKUs that are missing or don't match. ## How Uncap helps Uncap's guide to [managing millions of electronics SKUs](/post/managing-millions-electronics-skus) is direct about it: naming conventions and rationalization matter little if the SKU data in your storefront does not match your ERP and warehouse. The guide's answer is to integrate Shopify with ERP systems so SKU-level inventory counts, pricing and order data stay aligned automatically across every system, instead of someone manually reconciling spreadsheets between platforms. ## Related terms - GTIN (Global Trade Item Number) - UPC (Universal Product Code) - PIM (product information management) - Case pack - System of record - EDI 846 ## Sources - Shopify Help Center: Using SKUs to manage your inventory - GS1 US: What is a GTIN? - Shopify GraphQL Admin API: ProductVariant ## Frequently asked questions ### What is SKU vs UPC? A UPC is a GS1 number on a barcode that identifies the same product for every seller. A SKU is an internal code that a business creates for its own inventory, so the same UPC item can sit under different SKUs at different sellers. ### How do I get SKU for my product? You create it yourself. Pick a format that encodes the attributes you need, keep it short and consistent, and enter one unique SKU per variant. In Shopify you add it in the Inventory section of the product or variant. ### What does 100 SKUs mean? It means the business stocks 100 distinct products or variants, each with its own SKU. Every variant counts, so 10 products that each come in 10 size and color combinations add up to 10 x 10 = 100 SKUs.