Check a GTIN without inventing a product identifier
A GTIN is assigned to a product. Its check digit helps detect typing errors; it does not prove that the number belongs to the item you sell.
Keep the original digits
Store GTINs as text in spreadsheets so leading zeroes survive export. Supported GTIN lengths are 8, 12, 13 and 14 digits. Spaces, scientific notation and stripped leading zeroes can break otherwise valid identifiers.
What the check digit does
For the digits before the final check digit, count from the right and alternate weights of 3 and 1. The check digit makes the weighted sum divisible by 10. The checker performs this calculation locally.
A passing check is not proof of ownership
A made-up number can pass the arithmetic test. Confirm the identifier against manufacturer data or appropriate GS1 records. Never generate a replacement GTIN just to make a validation error disappear.
When no GTIN exists
Requirements depend on the product. Review brand, MPN and identifier_exists using Google’s specification. Do not mark identifier_exists as false simply because your export is missing an assigned identifier.
Source: Google’s product data specification. Reviewed September 22, 2026. Check the current specification for your market and product.
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