How to Validate GTINs, UPCs and EANs Before You Upload a Product Feed

Product feeds · Practical guide · By Exultant Commerce

A GTIN (Global Trade Item Number) is the number behind a product’s barcode. UPCs and EANs are both GTINs. Shopping platforms use them to match your listing to a known product, so one wrong digit can leave an item limited or disapproved. This guide explains what a valid GTIN looks like, how the check digit works, and how to catch errors before a feed goes live.

The four GTIN lengths

GTIN-8 (EAN-8): 8 digits, used on small packs.
GTIN-12 (UPC-A): 12 digits, the standard retail barcode in North America.
GTIN-13 (EAN-13): 13 digits, used in most other markets. ISBN-13 book numbers are GTIN-13s too.
GTIN-14: 14 digits, usually for cases and multipacks.

Any other length is not a GTIN. A 10- or 11-digit value is almost always a number that has lost its leading zeros.

How the check digit works

The last digit of every GTIN is calculated from the others. To check one by hand:

Drop the last digit and read the remaining digits from right to left.
Multiply the first by 3, the second by 1, the third by 3, and so on.
Add the results together.
The check digit is the amount needed to reach the next multiple of 10, or 0 if the total already ends in 0.

Worked example: take the UPC 036000291452. Its first eleven digits, read right to left, are 5, 4, 1, 9, 2, 0, 0, 0, 6, 3, 0. Weighted, that is 15 + 4 + 3 + 9 + 6 + 0 + 0 + 0 + 18 + 3 + 0 = 58. The next multiple of 10 is 60, so the check digit is 2, which matches the final digit.

Why identifiers fail even when the product is real

Stripped leading zeros. Spreadsheets treat GTINs as numbers and drop the zeros at the front. Format the column as text before you paste or import.
Scientific notation. A value such as 8.90E+12 means the original digits are gone. Re-export from the source system.
The wrong number in the field. SKUs, manufacturer part numbers and Amazon ASINs are not GTINs.
One GTIN on several variants. Each size and colour normally has its own number.
Restricted ranges. Numbers in the 02, 04 and 2 ranges are reserved for in-store use, and Google Merchant Center flags them as restricted.

A valid check digit is not proof

The check digit only tells you the number is well formed. It does not confirm that the GTIN belongs to your product or brand. Compare identifiers against the manufacturer’s records, and never invent a GTIN to clear a feed error. If a product has no GTIN, follow the platform’s rules for products without identifiers instead.

Check a whole feed in one pass

Paste a column of identifiers into the free GTIN, UPC and EAN validator to test length and check digits in bulk, then export the invalid rows. The duplicate ID checker and the GMC feed auditor cover the other common causes of identifier errors. For the wider process, read our product feed optimization guide or see our product feed management services.

Need help cleaning up product identifiers?

Exultant Commerce audits feeds, fixes attribute errors and maintains catalog data for brands and agencies. Tell us what you are seeing and which channels are affected.

Discuss your product feed →

Platform requirements can change. Check each platform’s current documentation before making changes.

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