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UPC Check Digit

How to calculate a UPC-A check digit

When you look at a UPC version A barcode, the check digit is the 12th digit in the lower right corner of the symbol. The UPC check digit is the last digit and is calculated based on the preceeding 11 digits.

When a barcode is scanned the UPC check digit insures that the scanner or cash register decodes the barcode correctly. If the check digit scanned doesn’t match the first 11 digits in the barcode, the scanner won’t decode it, assuming that it’s a bad barcode.

UPC Check Digit Calculator

Enter an 11- or 12-digit UPC number:

Free Downloadable Check Digit Wizard

We've created a UPC-A check digit wizard that you can download for free.



Calculate a UPC Check Digit By Hand

The last digit in a UPC barcode is a check digit based on the previous 11 numbers. Our example barcode number is “41234554321”.

  • 1. Add the digits in the odd-numbered positions (first, third, fifth, etc.) together.
  • 2. Multiply that number by three.
  • 3. Add the digits in the even-numbered positions (second, fourth, sixth, etc.) to the result.
  • 4. Find the result modulo 10 (i.e. the remainder when the result is divided by 10).
  • 5. If the result is not zero, subtract the result from ten.

4+2+4+5+3+1=19 19x3=57 1+3+5+4+2=15 57+15=72 and 8 makes 80.

UPC Check digit in Excel & VB

You can calculate the UPC check digit yourself, both as an Excel spreadsheet and as a Visual Basic function. Use either one as reference point when writing your code. Both the macro and function have comments in them that explain how it all works.

Excel macro
Visual Basic function

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