Calculate the check digit
Validate a list
Runs entirely in your browser. Your numbers are not sent or stored.
How the checker works
- Check digit: the last digit of every EAN, UPC and GTIN follows from the others. A typo or two swapped digits almost always show up.
- Type: 8 digits are an EAN-8, 12 a UPC-A, 13 an EAN-13, 14 a GTIN-14.
- GS1 prefix: the first three digits of the 13-digit form show the GS1 organisation that issued the number, or a special range.
- Special ranges: 020 to 029, 040 to 049 and 200 to 299 are for internal use only, such as store or variable-weight numbers. 978 and 979 are ISBNs for books. None of them work as a product ID on Amazon.
Which number for what
| Type | Digits | Used for |
|---|---|---|
| UPC-A (GTIN-12) | 12 | product number in the USA and Canada |
| EAN-13 (GTIN-13) | 13 | product number outside North America, a UPC-A with a leading 0 |
| EAN-8 (GTIN-8) | 8 | very small packages |
| GTIN-14 | 14 | cases and cartons, first digit = packaging level |
| FNSKU | usually 10 characters, X00… | Amazon's fulfillment ID for the FBA label, not a GTIN |
UPC and EAN for Amazon: what the checker can't see
A correct check digit only means the number is written correctly. To create a new product on Amazon it must be registered with GS1, and the data there, especially the brand, has to match your listing. Look a number up with Verified by GS1.
- Cheap UPCs from resellers are often registered to someone else. Amazon rejects those products or matches them to another listing.
- Your own brand without a barcode: you can apply for a GTIN exemption in Seller Central.
- Products already on Amazon: you list against the existing ASIN and don't need your own UPC.
Frequently asked questions
How do I check if a UPC or EAN is valid?
Recalculate the check digit: going from right to left and leaving out the last digit, multiply the digits by 3 and 1 alternately, add everything up and subtract the sum from the next multiple of ten. The result must equal the last digit. The checker above does this for whole lists.
How is a UPC check digit calculated?
Example 03600029145: from the right, times 3, times 1, times 3 and so on gives 58. Up to the next multiple of ten, 60, that's 2. The check digit is 2 and the full UPC is 036000291452.
Does the prefix tell me where a product was made?
No. The first digits only show which GS1 organisation issued the number. A US brand manufacturing in China usually has a UPC starting with 0 or 1.
Is a number with a correct check digit valid for Amazon?
Not automatically. The check digit only shows the number is consistent. Amazon checks product IDs against the GS1 database, and the number has to belong to the brand you list. You can look it up with Verified by GS1.
What is the difference between UPC, EAN and GTIN?
GTIN is the umbrella term. A UPC-A is a GTIN-12, an EAN-13 is a GTIN-13, an EAN-8 a GTIN-8. The GTIN-14 identifies cases and cartons, its first digit is the packaging level.
Are my numbers stored?
No. The checker runs entirely in your browser.
More free tools: check which Amazon reviews you can get removed, Amazon FBA calculator for the UK and Europe, Amazon FBA calculator for amazon.com, FNSKU label generator, UPC code generator with how to get real UPCs, Amazon image requirements checker, A+ content image sizes for every module, GPSR checklist for Amazon, unit price calculator for the German Grundpreis, ACOS and ROAS calculator for your ads, search terms byte counter for backend keywords and titles, listing checker with a score from 0 to 100. All in one place: free Amazon seller tools. Numbers from over 1,200 checked listings: Amazon Listing Study 2026.
Sources
Updated October 21, 2026. The checker calculates the check digit following GS1. Whether a number is registered and who owns it, only GS1 can tell.