What Is a GTIN and How to Check If a Barcode Is Valid
GTINs, EANs and UPCs explained, how the check digit catches errors, and when online sellers need a real barcode.
A GTIN โ Global Trade Item Number โ is the number behind a product's barcode. It identifies a specific product (brand, model, variant) anywhere in the world. Google Shopping, Amazon, Flipkart and most marketplaces use GTINs to match your listing with the same product elsewhere, which is why a missing or invalid GTIN is one of the most common feed errors.
GTIN, EAN, UPC, ISBN: the same family
- GTIN-12 (UPC-A) โ 12 digits, common in North America.
- GTIN-13 (EAN-13) โ 13 digits, used in India, Europe and most of the world.
- GTIN-8 (EAN-8) โ 8 digits, for very small packages.
- GTIN-14 โ 14 digits, usually for cartons and cases.
- ISBN โ book numbers; modern 13-digit ISBNs start with 978 or 979 and are GTIN-13s.
They all belong to the same system, managed by the not-for-profit organisation GS1, which issues company prefixes to manufacturers.
How the check digit works
The last digit of every GTIN is a check digit calculated from the others. It catches typing mistakes. To calculate it:
- Starting from the right of the number without its check digit, multiply the digits alternately by 3 and 1.
- Add the results.
- The check digit is whatever brings the total up to the next multiple of 10.
If one digit is mistyped, the calculation almost always fails โ which is why a validator can instantly tell you a number is wrong. It cannot, however, tell you whether the number belongs to your product.
Do you need a GTIN?
- Selling branded products made by others: yes. Use the manufacturer's GTIN printed on the packaging. Google expects it for products that have one.
- Selling your own brand in retail or on marketplaces: usually yes. Get GS1 barcodes for your company (GS1 India in India).
- Handmade, custom or one-off items: often no. In Google Merchant Center, set
identifier_existstonoand provide brand where possible.
Avoid these GTIN mistakes
- Inventing numbers or using random generators. Even if the check digit passes, the number is not registered to you, and platforms can detect mismatches.
- Buying cheap resold barcodes from unofficial sellers. Many platforms check numbers against GS1 data and reject them.
- Reusing one GTIN across variants. Each size and colour normally has its own GTIN.
- Spreadsheet damage. Excel can turn barcodes into scientific notation (5.01E+12) or drop leading zeros. Format the column as text.
- Using in-store codes โ numbers starting with 2 are reserved for restricted internal use, such as weighed items.
Check your barcodes
The free GTIN validator checks GTIN-8, UPC-A, EAN-13 and GTIN-14 numbers and their check digits instantly. Read how to validate GTIN, EAN and UPC barcodes in bulk for a catalogue-wide approach. Then validate the whole feed with the feed validator.
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Frequently asked questions
Is EAN the same as GTIN?
An EAN-13 is a 13-digit GTIN. GTIN is the umbrella term.
Can I make up a GTIN for my product?
No. GTINs must be issued through GS1 to the brand owner. Use identifier_exists: no if your product has none.
Does a valid check digit mean the GTIN is correct?
It means the number is well-formed. It does not prove it belongs to your product.
Where do I get barcodes in India?
From GS1 India, which issues company prefixes and barcodes to brand owners.