What a GTIN is

A GTIN, the Global Trade Item Number, is a number that uniquely identifies a single trade item. A trade item is anything that can be priced, ordered or scanned, from a single can of soup to a pallet of soup cans. The number is allocated by GS1, the global standards body that runs barcoding rules retailers use today.

Every product you buy at a supermarket has one. The 13-digit number at the bottom of an EAN-13 barcode? That is a GTIN-13. For background, the GTIN Wikipedia entry covers the history and the variants in detail. When a retail scanner reads a barcode at the till, the GTIN is what comes out the other side, and the till's price-lookup database does the rest.

GTINs are the world's product identity layer. GS1 Digital Link is the URL that wraps a GTIN.

The four lengths

GTINs come in four lengths, each suited to a different application:

  • GTIN-8. 8 digits. For very small consumer items where a longer code wouldn't fit.
  • GTIN-12. 12 digits. The North American format inside UPC-A barcodes.
  • GTIN-13. 13 digits. The global consumer format inside EAN-13 barcodes. Most common.
  • GTIN-14. 14 digits. For cases, outers and trade items containing multiple consumer units.

All four formats can be padded with leading zeros to 14 digits when stored in databases. The platform accepts any of these lengths and validates accordingly.

The mod-10 check digit

The last digit of every GTIN is a mod-10 check digit. It's not part of the identity, it's a self-validation digit that lets a scanner detect a single-digit transcription error before the number goes anywhere.

The algorithm is simple. Starting from the rightmost digit before the check digit:

  1. Multiply alternate digits by 3 and 1, starting with 3 on the rightmost.
  2. Sum the products.
  3. Subtract the sum modulo 10 from 10. If the answer is 10, use 0.

That final number is what the check digit must be. If it doesn't match, the number is invalid.

GTIN candidate: 0931234567890?
weights:        3 1 3 1 3 1 3 1 3 1 3 1 3
products:       0 9 3 1 6 2 12 5 18 7 24 9 0
sum = 96
(10 - 96 mod 10) mod 10 = 4

valid GTIN: 09312345678904

The GTIN validator runs this in your browser. Paste any GTIN and you'll get a check-digit breakdown.

How GTIN allocation works

You don't make up a GTIN. You apply for one through your local GS1 member organization. Each country has one. They allocate a company prefix registered to your business, and you assign GTINs from inside that prefix to each of your SKUs.

Reuse rules matter. GS1 generally requires a waiting period (commonly four years for consumer products) before a discontinued GTIN can be reassigned to a different product. Reuse rules vary by category and region, and getting them wrong creates retail collisions.

How the platform handles GTINs

The platform's job is to validate, format and stabilise. We do not allocate.

  • Inline mod-10 validation on every product create or edit.
  • Accepts GTIN-8, GTIN-12, GTIN-13, GTIN-14 with or without leading zeros.
  • Locked once published, so the public Digital Link URL stays stable.
  • Carried into the GS1 Digital Link URL pattern /01/{gtin}.
  • Optionally combined with batch (/10/) and serial (/21/) qualifiers.
Validate a GTIN Build a Digital Link

Quick answers

Where do I get a GTIN?
From your local GS1 member organization. They allocate GTINs through a company prefix that's registered to your business. We don't allocate GTINs ourselves. Once you have one, the platform validates the format and uses it.
What's the difference between GTIN-13 and GTIN-14?
GTIN-13 is the most common consumer product number, the same one inside an EAN-13 barcode. GTIN-14 is used for cases and outers (the trade item containing multiple consumer units), with a packaging-level indicator digit at the front.
Can I reuse a GTIN if a product is discontinued?
Generally no. GS1 reuse rules require waiting periods (typically four years for most consumer products) before a GTIN can be reassigned. Reuse rules vary by category and region, so check with your GS1 member organization before reusing any number.
Does the platform allocate GTINs?
No. Allocation is GS1's role. The platform validates GTINs you bring, formats them into GS1 Digital Link URLs, and locks the GTIN once a product is published so the public URL stays stable.