GTIN format reference

GTIN formats, digit lengths, and how to store them without breaking them.

There are four GTIN lengths, one storage rule that prevents most catalog errors, and one check digit that tells you whether a value was retyped correctly. This page is the reference, not an introduction.

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Four lengths

GTIN-8, GTIN-12, GTIN-13 and GTIN-14 are the only valid forms.

One column

Store every GTIN right-justified in a 14-digit text field.

One check

The final digit is a modulo-10 check over the preceding digits.

The four lengths

Each GTIN length exists for a different packaging level.

A Global Trade Item Number identifies a trade item, which means a specific product in a specific packaging configuration. The same physical product sold as a single unit, an inner pack and a case is three trade items and needs three distinct GTINs. The length you use is determined by the barcode symbol printed on that packaging level, not by preference.

Consumer units carry a UPC-A or an EAN-13 symbol in almost every catalog. Cases and pallets carry an ITF-14 or a GS1-128 symbol. Very small packs that cannot physically fit a full EAN-13 use the shortened EAN-8 symbol, which is issued sparingly because the number capacity is limited.

GTIN format	Digits	Where it is normally used
GTIN-12	12	UPC-A symbols. The retail default in the United States and Canada.
GTIN-13	13	EAN-13 symbols. The retail default in most other markets.
GTIN-8	8	EAN-8 symbols on packs too small to carry an EAN-13.
GTIN-14	14	Cases, cartons and pallets, carried in ITF-14 or GS1-128.

Storage

Store every GTIN right-justified to fourteen digits, as text.

The GS1 General Specifications define a single fourteen-digit data structure that all four lengths fit into. A GTIN-12 becomes two leading zeros plus the twelve digits. A GTIN-13 becomes one leading zero plus the thirteen digits. A GTIN-8 becomes six leading zeros plus the eight digits. Once every value is stored this way, a single column can hold identifiers for every packaging level and comparisons between systems stop producing false mismatches.

The failure mode is almost always a spreadsheet. A GTIN column typed as a number loses leading zeros, and a thirteen-digit value can be rendered in scientific notation and rounded, which destroys the last digits silently. Import supplier identifier columns as text, and check the length of the imported values before you accept the batch rather than after a channel rejects it.

One fourteen-digit text column, never a numeric column
Leading zeros preserved rather than trimmed on import
Length and check digit validated at import, not at publish
Original supplier value retained beside the normalized one

Check digit

The last digit is a modulo-10 checksum you can verify yourself.

Every GTIN ends in a check digit computed from the digits before it. Working from the digit immediately to the left of the check digit and moving leftwards, multiply alternate digits by 3 and 1, starting with 3. Add the products together, then subtract the total from the next multiple of ten. The result is the check digit. If it does not match, the value was mistyped, truncated or reformatted somewhere between the supplier and your catalog.

This is worth running as an import rule rather than as a manual step. A check digit failure is a cheap, deterministic signal that a supplier file has a formatting problem, and it catches errors long before a marketplace or a retailer rejects a listing for an invalid identifier.

Alternate weights of 3 and 1, applied right to left
Check digit equals the amount needed to reach the next multiple of ten
A failed check digit means a transcription problem, not a rare product
Run it at import so the fix stays with the source file

GTIN-14

The first digit of a GTIN-14 is an indicator, not part of the item number.

A GTIN-14 for a case is built from an indicator digit, the GTIN-13 of the item inside it without its check digit, and a freshly calculated check digit. The indicator distinguishes different packaging configurations of the same base item, so an inner pack of six and a case of twenty-four can share the same base number with different indicators.

Indicator values 1 through 8 are used for fixed-measure configurations. Indicator 9 is reserved for variable-measure trade items, where the quantity inside the case is not constant. Confirm the current allocation rules in the GS1 General Specifications before assigning indicators across a catalog, because the packaging hierarchy you publish to a retailer has to match the one you barcode.

Indicator digit plus base item number plus a recalculated check digit
Indicators 1 to 8 for fixed-measure packaging configurations
Indicator 9 reserved for variable-measure trade items
Each packaging level is a separate trade item with its own record

Frequently asked questions

Clear answers before you evaluate a PIM.

Is a GTIN the same thing as a barcode?

No. The GTIN is the number. The barcode is a symbol that encodes it. The same GTIN-13 can appear as an EAN-13 symbol on the pack and as a plain number in a data feed, and a GTIN-14 for the case is encoded in ITF-14 or GS1-128 rather than EAN-13.

Which GTIN length should my catalog store?

Store all of them in one fourteen-digit text field, right-justified with leading zeros. Keep the length the supplier sent as a separate observation if you need it for label printing, but normalize the value you compare and publish.

Do I need a new GTIN when the pack size changes?

Yes. A different packaging configuration is a different trade item. GS1 also expects a new GTIN when a change would make the previous item unacceptable to a trading partner or a consumer, such as a change in net content or a formulation change that is declared on the pack. Confirm the current change rules with your GS1 Member Organisation before a large relabelling.

Can a GTIN be reused after a product is discontinued?

GS1 restricts reuse rather than forbidding it outright, and the rules differ by sector. Reuse is not permitted for healthcare trade items, and elsewhere a waiting period after the last supply applies. Because retailer and marketplace systems can hold historical data for years, treat reuse as a last resort and confirm the current rule with your GS1 Member Organisation.

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GTIN formats, digit lengths, and how to store them without breaking them.

Each GTIN length exists for a different packaging level.

Store every GTIN right-justified to fourteen digits, as text.

The last digit is a modulo-10 checksum you can verify yourself.

The first digit of a GTIN-14 is an indicator, not part of the item number.

Clear answers before you evaluate a PIM.

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