What Is a GTIN? GTIN-8, 12, 13 and 14 Explained

A number, not a barcode

The single most useful distinction in this whole topic is between the GTIN and the symbol that prints it. A GTIN is a sequence of digits. A barcode is a way of drawing that sequence so a scanner can read it. The same GTIN can wear several different uniforms — twelve-digit UPC-A on a US shelf, thirteen-digit EAN-13 on a UK shelf, fourteen-digit ITF-14 on the outer case, and a GS1 Digital Link URL inside a 2D code on the consumer pack — and it's still one number.

That mental model — GTIN as identity, barcode as packaging — keeps you out of trouble when teammates use the words interchangeably. If a retailer asks for "the barcode", they almost always mean the GTIN. If a supplier sends you a CSV of GTINs, they may or may not include the GTIN-14 case form alongside the consumer-pack GTIN-13. Knowing they're the same number in different lengths is the difference between matching products and accidentally duplicating them.

Anatomy of a GTIN

A GTIN is built from three parts: a GS1 company prefix (assigned to you), an item reference (assigned by you), and a check digit (calculated). Take the GTIN-13 we opened with:

The split point between prefix and item reference moves depending on your allocation. Large brands receive short prefixes (sometimes only six digits) which leaves them room for hundreds of thousands of item references. Smaller brands receive longer prefixes and get fewer references in return. You don't need to know where the split sits to read or store a GTIN — you treat the whole number as opaque — but it's useful to know it's in there.

The four lengths

GTIN comes in four lengths, all valid, all globally unique, all defined by GS1. The length you end up with depends on the company prefix you were issued and the packaging level you're identifying.

GTIN-12 and GTIN-13 identify the consumer unit you scan at a till. GTIN-14 identifies a packaging hierarchy above that — the case of six, the carton of twenty-four — and its leading digit (the "indicator") tells you the level. GTIN-8 is reserved for items where there simply isn't room for thirteen digits of bars, like individually-wrapped sweets and electronic component packs.

For deeper coverage of why UPC-A and EAN-13 are different in the first place, see the UPC vs EAN guide. For the spec-level reference to symbology behaviour, see the barcode formats field guide.

How the check digit works

The trailing digit of every GTIN is calculated from the others by a single mod-10 rule. It's the same algorithm for GTIN-8, 12, 13 and 14 — which is why one validator handles them all. Here's the math for 5012345678900, walked through end-to-end:

1. Take the body — the digits without the trailing check — 501234567890.
2. Read it right-to-left and multiply each digit alternately by 3 and 1, starting at 3:
   0×3 + 9×1 + 8×3 + 7×1 + 6×3 + 5×1 + 4×3 + 3×1 + 2×3 + 1×1 + 0×3 + 5×1
= 0 + 9 + 24 + 7 + 18 + 5 + 12 + 3 + 6 + 1 + 0 + 5 = 90.
3. The check digit is whatever brings that sum to the next multiple of ten. 90 is already a multiple of ten, so the check digit is 0. Append it to the body and you have a full GTIN-13: 5012345678900.

You don't have to do this on paper. Paste the same value into the GTIN Validator and it'll confirm the length class and the check digit in one step:

When you're building GTINs from a new company prefix — say you just received the prefix 501234 and want to mint item reference 56789 — the Check Digit Calculator gives you the trailing digit straight away:

Storing GTINs without losing them

The single biggest source of GTIN bugs has nothing to do with GS1 and everything to do with how the digits end up in a database. Two rules of thumb cover most of the failure modes:

1. Store every GTIN as a 14-character string, left-padded with zeros. A GTIN-12 of 036000291452 goes in as 00036000291452. A GTIN-13 of 5012345678900 goes in as 05012345678900. One column, one length, no ambiguity. You can render the shorter form for display or printing whenever you need to.
2. Validate the check digit at the boundary. Any supplier feed, scanned input or free-text field gets verified before it is trusted. That catches transposed digits, stripped zeros and well-meaning spreadsheet auto-formatting in one pass.

When you receive a large supplier feed and want to verify every row at once, the Batch Barcode Tools page runs the same validation against a pasted list and gives you a flagged CSV back. Drop a list of GTIN-13s into it before importing and the typos surface in seconds.

When you need a new GTIN

A common mistake when launching a product variant is to reuse an existing GTIN "because it's basically the same thing". Retailers and marketplaces actively police this and will reject listings. The rule from GS1 is conservative: anything a shopper would consider a different product needs a new GTIN. In practice that means:

• A different flavour, scent, colour or recipe needs a new GTIN.
• A different pack size (250 g vs 500 g) needs a new GTIN.
• A different packaging hierarchy (single can vs case of six) needs a new GTIN — usually a GTIN-14 with an indicator digit.
• A different language on the pack typically does not need a new GTIN.
• A promotional sleeve over the same product does not need a new GTIN.