How do I interpret sp_spaceused() results when trying to determine a table's true size on disk?

Question

I am trying to do some capacity planning based on some current database table sizes in SQL Server 2008. The goal here is to figure out how much disk storage I may potentially need in the future based on "past weather".

I didn't see anything in the MSDN doc page for sp_spaceused() about how exactly to interpret the results for one table. http://msdn.microsoft.com/en-us/library/ms188776.aspx

Is it simply a matter of summing: reserved + data + index_size + unused?

Thanks.

Answer 1

As I recall, it's:

reserved = ( data + index_size + unused )