# UPC–A Check Digit Calculator

The last digit of an UPC–A barcode is a check digit that is used for human transcription error detection. Here it is marked with a red square: ## Check Digit Formula

To compute the check digit follow the simple rules:

• Take all the digits in odd positions, add them and multiply by three;
• Take all the digits in even positions (except for the last one) and add to the number you got above;
• Divide that number by 10 and take the remainder;
• If the remainder is not 0, subtract it from 10.
• That’s it.

## Check Digit Calculator

Enter the barcode number into the field below to compute the check digit and see the maths behind:

Here goes the check digit calculation for barcode :

1. The digits in odd positions are: , their sum is , multiplied by 3 it is ;
2. The digits in even positions (except the last one) are: , their sum is , added to the number above it is ;
3. Dividing  by 10 gives us  as a remainder;
4. It is not zero, so subtracting it from 10 to get the check digit: .
5. It is zero, so just using it as is.

The check digit is ""

If you work with barcodes, have a look at our barcode generator which will save you much more time than this calculator.