Barcode Generator — EAN-13 and UPC-A
A barcode number is not arbitrary. The final digit is a checksum computed from the ones before it, and marketplaces verify it on upload. Get it wrong and the listing is rejected with an error that usually says nothing more useful than “invalid GTIN”.
This calculates that digit, and validates codes you already have. Both EAN-13 and UPC-A, using the GS1 modulo-10 standard.
Free, no signup, runs entirely in your browser — nothing you type is sent anywhere. Last updated .
Calculate a check digit
Enter the digits you have and the final one is computed for you.
The global default. Used everywhere outside North America and accepted by every marketplace that asks for a GTIN.
12 / 12 digits
5901234123457Check digit 7 appended.
Validate an existing code
Paste a full barcode to check it before a marketplace rejects it.
13 digits
Valid EAN-13
The check digit matches. This code will pass a marketplace's format validation.
This checks the arithmetic only. It cannot tell you whether the number is licensed to you — barcode numbers are issued through GS1, and the prefix identifies the company that owns the product.
What it does
Inside the barcode generator
- Completes a partial EAN-13 or UPC-A
- Validates an existing code and shows the expected digit
- Explains which digit was wrong, not just that it failed
- Pure arithmetic — nothing is transmitted
Guide
Barcode Generator: what actually matters
What the check digit actually does
It catches transcription errors. Multiply the digits alternately by 3 and 1 from the right-hand end, sum them, and the check digit is whatever takes that sum up to the next multiple of ten. That scheme catches every single-digit mistake and most transpositions — which is precisely the class of error a human makes retyping a number off a box.
EAN-13 and UPC-A are the same thing
A UPC-A is a 12-digit code used mainly in North America; an EAN-13 is the 13-digit global form. A UPC-A is simply an EAN-13 with a leading zero, and the check digit is identical under both readings. If you have one you effectively have the other, which is why a marketplace will often accept either.
This tool does not issue you a barcode
That distinction matters commercially. Barcode numbers are licensed from GS1, and the prefix inside the number identifies the company that owns the product. This calculates and validates the number — it cannot assign you a legitimate one. Buying a cheap resold barcode from a third party is a common shortcut and a common reason for a listing being pulled later, because the prefix belongs to someone else.
When you can skip the barcode entirely
Handmade goods, private-label products in some categories, and bundles often qualify for a GTIN exemption. The application usually needs photographs of the product and its packaging showing no existing barcode. It takes time to be granted, so start it before you plan to launch rather than after the upload has already failed.
FAQ
Common questions
Does this give me a barcode I can legally use?
No, and be careful of any free tool that claims otherwise. It calculates and validates the check digit for a number you already have the rights to. Legitimate barcode numbers are licensed through GS1, and the company prefix inside the number identifies the licensee.
My marketplace rejected a code that looks correct. Why?
Paste it into the validator above. The most common causes are a mistyped digit, a code that is actually 11 or 14 digits after stripping formatting, or a leading zero that a spreadsheet removed on export. The validator shows the digit that was expected against the one you supplied.
What is the difference between a GTIN, a UPC and an EAN?
GTIN is the umbrella term. UPC-A (12 digits) and EAN-13 (13 digits) are both GTINs, as is the 14-digit case-level GTIN-14. When a marketplace asks for a GTIN it will accept whichever of these applies to your product.
Can I get a scannable barcode image, not just the number?
Not from this page — it calculates and validates the number itself. The barcode generator inside the ListIQ Pro app renders a real scannable barcode you can download, covering EAN-13, UPC-A, Code128 and QR, with the same check-digit validation applied. Use this page to check a number, and the app when you need the artwork.
Can I use one barcode for several product variants?
No. Every distinct buyable variant — each size, each colour — needs its own GTIN. Reusing one across variants causes the marketplace to merge them into a single listing, which corrupts inventory and reviews. Your internal SKU can carry the variant structure; the GTIN cannot.
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The barcode is the easy part
Once the product has a valid GTIN it still needs a title, bullets, backend keywords and compliant images. ListIQ Pro generates all of it from a single photo.