How to Create SKUs for Your Products
By Selling Fee Tools team ·
A SKU (stock keeping unit) is your own code for each product you stock, down to the colour and size. It links a marketplace listing to the right item on your shelf, and it is how you read stock reports, pick orders and reorder. This guide shows how to build SKUs that stay readable as your catalogue grows.
SKU or GTIN?
They are different things, and most marketplaces ask for both:
- A SKU is internal. You make it up, in any pattern you like, and it only has to be unique in your own catalogue.
- A GTIN (UPC or EAN) is a globally registered number that comes from GS1 and identifies the product everywhere it is sold. You can’t make one up. See GTIN, UPC and EAN barcodes explained.
What makes a good SKU
- Unique: one code per variant, never reused.
- Short enough to read out loud and type.
- Consistent: built the same way for every product, so staff can tell what an item is from the code.
- General to specific: put the broadest part first (brand or category), then the product, then attributes such as colour and size.
- Letters and numbers only, with one separator such as a hyphen.
- Don’t start with zero: spreadsheets remove leading zeros, and 0042 turns into 42.
A pattern that scales
A common pattern is category – product or sequence – colour – size:
| Product | SKU |
|---|---|
| Hoodie, red, large | HD-0001-RED-L |
| Hoodie, red, medium | HD-0001-RED-M |
| Hoodie, black, large | HD-0001-BLK-L |
| T-shirt, white, small | TS-0002-WHT-S |
A sequence number padded with zeros (0001, 0002) keeps codes the same length and sorts correctly. If you have many categories, number each one separately to keep codes short.
Common mistakes
- Meaningless random codes: unique, but nobody can read them.
- Encoding things that change, such as price or supplier, so the SKU goes out of date.
- Duplicates across variants: two sizes with the same SKU break stock counts. WooCommerce rejects duplicate SKUs on import, while Shopify allows two variants to share one, which causes problems if you later move platforms.
- Very long codes: each platform has its own maximum length, so keep segments short if you sell on several.
Generate SKUs in bulk
The bulk SKU generator builds SKUs from a pattern you set: prefix, category code, colour and size, sequence number and separator, with a live preview. Paste your product list from Google Sheets or Excel, and it adds a SKU column to your data, makes any duplicates unique with -2, -3, and downloads the result as CSV.
Print them as barcodes
For warehouse labels and bin locations, print SKUs as Code 128 barcodes, which can carry letters, numbers and punctuation. The barcode generator makes them in bulk as SVG or PNG. Keep GTIN barcodes (UPC or EAN) for the product packaging.