GTIN check digit validator
Paste barcodes and see which Google will accept. The same test the free feed check runs on every gtin in a feed, for the numbers you have in front of you.
What it checks
Google’s gtin specification accepts 8, 12, 13 or 14 digits (EAN-8, UPC-A, EAN-13 or ISBN-13, ITF-14), spaces and dashes ignored, and validates the check digit. The tool strips anything that is not a digit, checks the length, recomputes the check digit, and flags the placeholder patterns merchants type to fill a required field. A 12-digit UPC is shown as the 13-digit GTIN it is sent as, with a leading zero, which is how the feeds we render carry it.
What each result means for Merchant Center
An invalid value is disapproved as “Invalid value [gtin]”. A missing value only limits performance, so an empty field is better than a wrong one; the missing-GTIN guide covers where to find real barcodes and what to do for products that have none.
Questions merchants ask
How is the check digit calculated?
From the right, the payload digits are weighted 3, 1, 3, 1 and so on, summed, and the check digit is whatever brings the total to a multiple of ten. The tool computes it and compares; a single typo anywhere in the number fails it.
My 11-digit UPC fails. Why?
A UPC-A has twelve digits. Spreadsheets drop a leading zero when they treat the column as a number, and 012345678905 becomes 12345678905, which is no GTIN length at all. Restore the zero.
Why does a valid-looking number show as a placeholder?
Patterns such as all zeros, one repeated digit or 1234567… pass the arithmetic and identify nothing. Google matches them to no product, and the free check treats them as missing. Leave the field empty instead.
Is this the same check Google runs?
Google validates length and check digit as its gtin page describes, and additionally knows whether the number exists in its catalogue. This tool does the first two; only Google can do the third.
Sources
Google Merchant Center Help, GTIN [gtin] and How to fix: Invalid value [gtin]; GS1, Global Trade Item Number.