TRP Polymer Solutions' O-Ring Size Guide allows you to find the size and tolerance of an AS-568A O-ring code. It also allows you to find the most appropriate O-ring for your application.
Alternatively, you can download the guide in Excel format.
AS-568A O-ring size and tolerance finder
Enter a valid AS-568A O-Ring code and click 'Go' to find the appropriate O-ring size and tolerance