GS1 Barcode Generator & Modulo 10 Check Digit Calculator – EAN-13 & UPC-A Maker
What is GS1 Modulo 10 Check Digit & Why Does It Matter?
Every commercial retail product barcoded with UPC-A or EAN-13 relies on the official GS1 Modulo 10 check digit algorithm. The final digit is not a random number; it is a cryptographic checksum calculated from the preceding 11 or 12 digits. If the checksum fails, supermarket point-of-sale (POS) barcode scanners, Amazon FBA fulfillment scanners, and logistics sorters will reject the barcode as invalid or corrupted.
How the GS1 Check Digit Algorithm Works
- Starting from the right-hand position before the check digit, multiply alternate digits by 3 and 1.
- Sum all the multiplied numbers together.
- The check digit is the smallest number that must be added to the sum to make it a multiple of 10:
(10 - (Sum % 10)) % 10.
ISO/IEC 15420 Compliant Barcode Rendering
This generator draws standard guard bars (start, center, stop) and utilizes precise module widths and quiet zones required for 100% first-pass scan rates on commercial laser and CCD optical scanners.
Frequently asked questions
What is the difference between UPC-A and EAN-13?
UPC-A is a 12-digit standard primarily used in the United States and Canada. EAN-13 is a 13-digit global standard used throughout Europe, Asia, and Latin America. In fact, UPC-A is a subset of EAN-13 with a leading zero.
Can I print these barcodes on product retail packaging?
Yes. The exported PNG is rendered in crisp high-resolution suitable for offset packaging printing, thermal labels, and shrink sleeves.
Are my product catalog codes uploaded anywhere?
No. The entire GS1 checksum calculation and canvas rasterization execute 100% on your local machine.
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