Hello,
SEP Database Sizing Tool's Excel sheet hasn't changed, it should be able to give you relatively accurate results for SEP 12.1 too. You may want to increase the size of the content packages (they were quite small when the sheet was originally done) but if you have a lot of logs, they won't make much difference to the sizing.
Check Paul Murgatroyd's (Principal Product Manager, Symantec Endpoint Protection) comment in the Thread below:
https://www-secure.symantec.com/connect/forums/sizing-db-sep-121
Check these Articles on the Tool:
Planning for Microsoft SQL database creation and management with Symantec Endpoint Protection 11.x
http://www.symantec.com/docs/TECH105256
How to use SEPM Database sizing tool
https://www-secure.symantec.com/connect/articles/how-use-sepm-database-sizing-tool
Hope that helps!!