Check Digit Calculator

The last digit of a bar code number is a computer Check Digit which makes sure the bar code is correctly composed.

How to calculate a Check Digit manually

Using sample code 72641217542 as an example, follow the 5 steps below to find the check digit:

Step One: From the right to the left, start with odd position, assign the odd/even position to each digit.

Step Two: Sum all digits in odd position and multiply the result by 3. (7+6+1+1+5+2)*3=66

Step Three: Sum all digits in even position. (2+4+2+7+4)=19

Step Four: Sum the results of step three and four: 66+19=85

Step Five: Divide the result of step four by 10. The check digit is the number which adds the remainder to 10. In our case, divide 85 by 10 we get the remainder 5. The check digit then is the result of 10-5=5.