SKU naming convention guide.

Eight rules

1. Make it permanent. A SKU names a sellable item for life. Do not reuse one for a different product, even a discontinued one.
2. Letters, digits, hyphen or underscore only. Spaces and symbols cause trouble in CSV imports, barcode scanners and URLs.
3. One case. Use capitals throughout. Systems that ignore case will treat Hoo-1 and HOO-1 as the same SKU.
4. General to specific. Category, then attributes (colour, size), then a sequence. It sorts sensibly and reads aloud.
5. Avoid O, I and l next to digits. They look like 0 and 1 on a packing slip.
6. Beware leading zeros and E. Spreadsheets drop the zero from 00123 and turn 1E5 into 100000. Start numeric SKUs with a letter, or format the column as text.
7. Keep it short enough to read. Check your sales channel for its own maximum length rather than guessing.
8. Do not use a barcode as the SKU. A UPC, EAN or GTIN identifies a trade item for anyone who scans it; the SKU is yours. Keeping them separate lets you change either without touching the other.

Example

HOO-BLA-L-001: Hoodie, Black, Large, first in the Hoodie category. To build a list like this in bulk, use the SKU generator; to find duplicates across a catalogue CSV, use the variant and SKU collision checker.

The checker flags problems that commonly break imports; it does not know any marketplace’s own rules, and a clean result does not mean a platform will accept the SKU.

Sources retrieved October 2026. These rules are practical conventions drawn from how spreadsheets and scanners behave, not from a standard. The statement that GTINs identify trade items and that a valid GTIN is a number with a correct GS1 check digit is from the GS1 General Specifications, Release 26.0.

More identifier tools

SKU generator · Variant & SKU collision checker · EAN-13 / UPC-A check digit validator · UPC-A barcode generator · ASIN format validator · Bulk barcode label generator