EAN / UPC / GTIN Check-Digit Validator
Every EAN, UPC and GTIN barcode number ends in a check digit — a single digit calculated from all the others using a fixed formula, whose only job is to catch typos and scanning errors. A number with the wrong check digit isn't "close enough": a marketplace or a warehouse scanner can reject it outright.
This tool runs that same calculation in your browser. Paste a code you already have — from a supplier, a product spec sheet, or a label you're about to print — and it tells you instantly whether the check digit is correct, or what it should be if it isn't. Paste a whole list, one code per line, to check a spreadsheet's worth at once before you upload a catalog to Amazon, Etsy or Shopify.
The Generate tab does the reverse: give it the digits you were assigned (by GS1, or by a supplier) without the check digit, and it calculates the correct one for you, so you end up with a complete, valid code ready to turn into an actual barcode image.
This tool checks the math only — it can't tell you whether a code is registered to your product in GS1's database, or whether a marketplace will accept it. For that, check with GS1 directly or your marketplace's listing requirements.
Frequently Asked Questions
What is a check digit, exactly?
It's the last digit of an EAN, UPC or GTIN barcode number, calculated from all the digits before it using a standard formula (the GS1 Modulo-10 algorithm). Its only purpose is error detection — if one digit gets mistyped or misread, the check digit almost certainly won't match anymore, so the error gets caught before the product is mislabeled.
How is this different from the Barcode Generator tool?
The Barcode Generator draws a scannable barcode image from a number you already have complete — it doesn't check whether that number's check digit is mathematically correct. This validator does the opposite: it doesn't draw anything, but it tells you whether a code is valid, checks a whole list at once, and can calculate a missing check digit for a new code. Once you have a valid, complete number, the Barcode Generator turns it into a printable image.
Can this tool assign me a new EAN or UPC number?
No — EAN, UPC and GTIN numbers have to be licensed to your company through GS1 (or bought in small quantities through a GS1-authorized reseller) before they're valid for retail use. This tool only does the check-digit math on numbers you already have; it doesn't register or issue new ones.
Does this work for ITF-14 and GTIN-14 case codes?
Yes. ITF-14 and GTIN-14 (commonly used for shipping cases and cartons rather than individual retail items) use the same GS1 Modulo-10 check-digit formula, just with 13 data digits instead of 12 — paste a 14-digit code and it's detected and validated automatically.