Barcode Number Generator - UPC-A and EAN-13 Check Digits
Enter or randomize the data digits for a UPC-A or EAN-13 barcode and get the correct check digit calculated using the real standard algorithm for each format.
11/11 digits entered
Result
Calculated Check Digit
2
Complete UPC-A Number
036000291452
How to Use the Barcode Number Generator
Choose UPC-A (12-digit) or EAN-13 (13-digit) format, then either type in the first 11 or 12 digits manually or click Randomize to fill them in for you. The tool calculates the correct final check digit using the real, standard algorithm for that format and shows the complete, valid barcode number. UPC-A sums the odd-position digits (1st, 3rd, 5th...) multiplied by 3 plus the even-position digits, while EAN-13 uses the same approach with the weighting reversed — odd positions weighted 1, even positions weighted 3 — to account for its extra leading digit.
Example
Entering the 11 digits 03600029145 in UPC-A mode calculates a check digit of 2, producing the complete, verifiable UPC-A number 036000291452 — a real published example confirming the check-digit math is correct.
Common Use Cases
- Calculating the correct check digit for a product barcode before printing packaging.
- Verifying that a manually typed UPC-A or EAN-13 number has the correct final digit.
- Generating sample, checksum-valid barcode numbers for testing inventory or POS software.
FAQs
- Does this generate a scannable barcode image? No — this tool only calculates and displays the numeric code with a correct check digit. If you need an actual scannable barcode image to download, use a dedicated barcode image generator instead.
- Can I use any random digits for a real product? Technically the check digit will always be mathematically valid, but real-world UPC and EAN codes are issued by GS1 with a registered manufacturer prefix — use an officially assigned code for actual retail products.
- What's the actual difference between the UPC-A and EAN-13 formulas? Both sum weighted digits and derive the check digit the same way, but the weight pattern is reversed between them: UPC-A applies the ×3 weight to odd positions, while EAN-13 applies it to even positions, which is a direct consequence of EAN-13 having one extra leading digit compared to UPC-A.