Ścieżka 01 · Moduł 02 z 4
GS1 identifiers: UPC, EAN, GTIN-14, who owns a code, and why marketplaces reject it
How the GS1 numbering system works — the GTIN family, one code per sellable unit, the packaging hierarchy — who a code is licensed to, the three ways marketplaces reject one, and a verification routine to run before any product is set up anywhere.
11 min czytania
W tym module nauczysz się
- ✓Tell a UPC, an EAN, a GTIN-14 and a GTIN-8 apart, and explain why they are one number family at different lengths.
- ✓Decide when a product needs its own GTIN, and name the packaging level each code in a hierarchy identifies.
- ✓Explain who a GTIN is licensed to and the three ways a code fails marketplace validation.
- ✓Record identifiers without damaging them, and keep the GTIN, the marketplace identifier and your SKU apart.
- ✓Run a five-step verification routine on any code before creating a product in a marketplace catalog.
A product is only as real as the code that identifies it.
The major marketplaces this guide covers ask for a barcode number before they will create a product, unless they grant an exemption, and they check that number against the same registry. Learn how the numbers are built, who owns them and how they fail, and most identifier rejections stop happening before you ever see one.
The GS1 system and the GTIN family
GS1 is the standards body, not a marketplace. A company licenses a GS1 Company Prefix, a block of digits identifying that company, and assigns item references under it, one per product; GS1 US also licenses single GTINs. The last digit is a check digit, calculated from the others by a fixed formula, so a typo usually fails on its own.
The GTIN family. A GTIN (Global Trade Item Number) is the number; the barcode is its printed form.
- GTIN-12 — the UPC (Universal Product Code), standard in North America.
- GTIN-13 — the EAN (originally European, now International Article Number), used almost everywhere else.
- GTIN-8 — for very small packages.
- GTIN-14 — the case and pack level: an indicator digit (1 to 8), the consumer unit's prefix and item reference, and a recalculated check digit, so the last digit changes. A case may instead get its own GTIN-13 or GTIN-12.
Pad a 12-digit UPC with two leading zeros for its 14-digit form: one family, different lengths.
One GTIN per sellable unit
Anything a buyer could order separately needs its own code. A different size, color, pack count, flavor, material or edition is a different GTIN, and so is a bundle of products that already have codes; reusing one code on two units is a mistake marketplaces catch.
The packaging hierarchy. One product exists at several levels, each able to carry its own GTIN:
- Each — the consumer unit (a UPC or EAN).
- Inner pack — several eaches inside the case.
- Case — the shipping carton, normally a GTIN-14.
- Pallet — many cases; a GTIN only when the pallet itself is ordered or priced, otherwise a shipping-container code.
3P lists the each; 1P ships the case. Selling to shoppers through a marketplace (third-party, 3P), the each code is the match key. Supplying the retailer as a first-party (1P) vendor, purchase orders and receiving run on the case GTIN-14; the each code describes its contents. Amazon 1P → Vendor catalog and Walmart 1P → Supplier catalog have the specifics.
Who the code belongs to, and three ways it fails
The GS1 record names a licensee. Every GTIN traces back to the company that licensed the prefix or single code: the licensee. Marketplaces check codes against GS1 and usually compare the licensee to the brand. Once the number is well formed, nearly all rejections are one of three:
- Not in GS1. Invented, lapsed, or from a reseller whose numbers were never licensed. The fix is a licensed code; a marketplace exemption is for products with no code, not a bad one.
- Licensed to another company. Resold codes usually land here, under the reseller's name. Often it is legitimate but undocumented: a parent company, contract manufacturer or distributor holds the prefix. Documents linking the two usually resolve it.
- Already in the marketplace's catalog. Under the same product, that is a match, not a create; under a different product, a duplicate or mis-assigned code to investigate.
Fixes are platform work: Amazon 3P → Brand programs and gating covers GTIN exemption and prefix whitelisting; Walmart 3P → Catalog troubleshooting covers Product ID conflicts.
Reading and recording identifiers
The barcode is not the record. A printed symbol can be misprinted, cropped or outdated; the GS1 record and your specification are the source, and the pack is checked against them.
Leading zeros are part of the number. A UPC beginning with 0 loses that digit when a spreadsheet treats it as a number, and any 12- to 14-digit code can turn into scientific notation, plausible-looking and invalid. Store identifiers as text; Foundations → Spreadsheet skills covers the mechanics.
One product, three identifiers, three owners. Foundations → Anatomy of a listing named them; keep them apart. The GTIN belongs to the licensee. The catalog identifier (Amazon's ASIN, Walmart's Item ID) belongs to the marketplace that assigned it. Your SKU (stock-keeping unit) names your offer on a marketplace or your item record as a supplier, never the product. Amazon 3P → Catalog fundamentals has the platform detail.
Keep one identifier table per product. GTINs by level, the each count per level, the licensee, and each marketplace's identifier once assigned.
A verification routine before any setup
Run this before you create anything, anywhere.
- Check the length and the check digit. Expect 8, 12, 13 or 14 digits and a last digit that passes the formula (GS1 publishes a free calculator). A failure here is a typo or dropped zero, not a licensing problem.
- Confirm it in the GS1 record. GS1's public lookup (currently Verified by GS1) shows whether the number is under a current license and who holds it; product details appear only if the licensee registered them. The licensee must be your brand or one you can document, and any details shown must match your product.
- Confirm the level. A GTIN-14 starting 1 to 8 is a pack or case code and has no place in a consumer-unit field; a leading 0 is just a padded each code.
- Search the marketplace catalog for the code. Under your product, match rather than create; under a different product, stop and investigate.
- Only then create. Record each result in your identifier table.
Pamiętaj
A GTIN is a claim about a product that a third party can verify. Verify it yourself first; a marketplace's rejection is the expensive way to learn what a two-minute lookup would have told you.
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Scenariusz
A fictional candle maker is preparing its first marketplace listings. Its spreadsheet shows SKU CNDL-VAN-8 (one 8 oz vanilla candle) with the code 1234567890, bought years ago from a reseller, and SKU CNDL-VAN-3PK (a 3-pack of the same candle) carrying the identical code. A retailer has also asked for the orderable unit, a carton of 12, which has no code at all.
Ćwiczenie
- Work out what is wrong with the single candle's code before any lookup, and what the lookup must then confirm.
- Decide whether the 3-pack can share the single's code, and why.
- List the codes the maker must have, by packaging level, before any marketplace setup.
Pokaż sugerowane podejście
The single's code has ten digits and a UPC twelve, so two digits are missing (three for an EAN): leading zeros lost in the sheet, or never a complete code. The reseller is a warning that it may not be in GS1 or may be licensed to someone else. Recover the full number from the pack or the original paperwork, run the check digit, then look it up in the GS1 record and read who the licensee is. The 3-pack is a different sellable unit and needs its own GTIN; sharing one code is a mistake marketplaces catch. The carton of 12 needs its own GTIN-14. The maker needs three codes licensed to its own company, each recorded as text in one identifier table.
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