How to design a SKU scheme that survives growth
A SKU (stock keeping unit) is a code you invent to identify a product or variant inside your own business. It is not a barcode number and does not need to be licensed from anyone. A tidy scheme saves time on picking, packing, reporting and spreadsheet imports. This guide gives a practical way to design one and generate the full list.
Rules worth following
Shopify's help page on SKUs lists guidelines that apply well beyond Shopify:
- Unique: every product variant gets its own SKU. A shirt in 3 sizes and 4 colors needs 12.
- Simple and consistent: each letter or number has a purpose, and an abbreviation means the same thing on every product (if BLK is black, it is black everywhere).
- Short: Shopify suggests no more than 16 characters, and says 4 to 8 can be enough for a small catalog.
- Safe characters: avoid spaces and special characters. Dashes and underscores are useful separators. Avoid mixes where 0 and 1 are easily confused with the letters O and I.
- Room to grow: if you have 100 products today and might have 1,000, make sure the format will not run out of combinations.
Marketplaces and shipping tools may have their own length or character limits for SKUs. Check the ones you use before you commit.
A scheme in five steps
- List the attributes that distinguish your products, in order of importance: for example product family, color, size.
- Assign a short code to each value. TEE for a T-shirt, BLK and WHT for colors, S, M and L for sizes. Write these down in a small table and keep it with your product data.
- Choose a fixed order and separator:
FAMILY-COLOR-SIZE-NNN, for exampleTEE-BLK-M-001. A trailing counter lets you add a second design in the same family without renaming anything. - Never reuse a SKU for a different product, even after you stop selling the old one, so that old orders and reports stay meaningful.
- Generate the full list from the table instead of typing it, so that a typo cannot create a near-duplicate.
Generating the combinations
In a spreadsheet, put one attribute per column and use a formula such as =A2&"-"&B2&"-"&C2 over every combination (a pivot or a cross-join tool helps). Barloom can generate the same list from a pattern like TEE-{BLK|WHT}-{S|M|L}-{#3}, which produces TEE-BLK-S-001 and so on, and lets you download the SKU list as CSV. It runs in your browser.
A SKU is an internal label. If a marketplace or retailer asks for a UPC or EAN, that is a separate number issued under license by GS1; see our guide on GS1 licensing basics. Shopify's page is used here as one example of marketplace guidance, and nothing in this guide implies any connection with Shopify.
Sources
- Shopify Help Center, "Using SKUs to manage your inventory": https://help.shopify.com/en/manual/products/details/sku (read 2026-10-28 as a search-index excerpt; the site blocks some automated fetching)
- Shopify Help Center, "Variants": https://help.shopify.com/en/manual/products/variants (read 2026-10-28 as a search-index excerpt)
Related tool: Barloom. Estimates and guidance only; check the source documents before relying on a figure.