ISBN-13 Check Digit Calculator

The last digit of an ISBN-13 barcode is a check digit. The check digit is used to detect errors mostly caused by human transcription.

ISBN-13 codes are based on EAN-13 barcodes, so the check digit is computed the same way.

The red mark below shows the check digit of an ISBN-13 barcode:

If you need to identify the country or language area that issued the code, or verify its hyphenated block structure, use the ISBN info tool.

Check Digit Formula

To compute the check digit follow the simple rules:

Sum all the digits in even positions and multiply by 3;
Add all the digits in odd positions (except for the last one which is check digit) to the number you’ve got;
Divide that number by 10 and take the remainder;
If the remainder is not 0, subtract it from 10.
Job done!

To save time on doing the math, simply enter the barcode numbers into the field below and we’ll do the job for you:

Here goes the check digit calculation for barcode :

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

The check digit is ""

If you work with barcodes, give our barcode software a try, it will save you much more time than this calculator.