Free tool, runs in your browser
GTIN, EAN and UPC Validator
Paste your barcodes to check their check digit instantly against the official GS1 algorithm.
Why does Google Shopping reject wrong GTINs?
The Global Trade Item Number (GTIN) ends in a mathematical check digit. Google Merchant Center calculates it automatically before indexing your catalog. If there's a typo, the product is flagged straight away as "Invalid product identifier" and stops showing in Shopping ads.
How the official GS1 formula works:
1. Multiply the digits from right to left, alternating weights of 3 and 1.
2. Add up all the products.
3. The check digit is what you need to reach the next multiple of 10.
Thousands of products in your WooCommerce store?
Melopo Radar checks every GTIN in your catalog every 24 hours and warns you before Google suspends your products.
No sign-up and nothing to install. We look at what anyone can see from outside.