The ISBN converter allows you to convert an ISBN 10 into an ISBN 13 and vice versa. In the past, publishers used ISBN numbers with 10 digits. However to ensure availability of numbers, since January 2007 the length of ISBN numbers was increased to 13. ISBN 13 is also compatible with the EAN bar code format, which is made up of 13 digits.
All ISBN Numbers should now have 13 digits. If you have purchased ISBN 10s, you will need to convert them into ISBN 13s.