I am trying to estimate the space used by certain tables in
a database vs entire database.

Trying to use sp_spaceused to get the data.

Example :
1.
use fadev
go
sp_spaceused

2.
use fadev
go
sp_spaceused User
go
sp_spaceused Dept
go
etc..etc

There is inconsistency in reporting. The table sizes
reported doesn't sum up to the database space used. Am I
doing something wrong. Appretiate any help.

sp_spaceused on entire DB shows 65G
sp_spaceused on individual tables shows 250G (summed up data
+ index).

Is there any other way of reporting ? I am trying to
determine the amount of space used in GB to calculate cost
associated with the disk.

Thank you