Script to calculate table and index sizes for all databases that login has access to.

per database table size

--sqlserver 2005 +
EXECUTE master.sys.sp_MSforeachdb 
'USE [?];

select getdate() as snapdate,serverproperty(''MachineName'') svr,@@servicename sv, ''?'' _dbname, nomTable= object_name(p.object_id),p.partition_id,p.partition_number,
        lignes = sum(
                CASE
                    When (p.index_id < 2) and (a.type = 1) Then p.rows
                    Else 0
                END
            ),
        ''memory (kB)'' = cast(ltrim(str(sum(a.total_pages)* 8192 / 1024.,15,0)) as float),
        ''data (kB)'' = ltrim(str(sum(
                CASE
                    When a.type <> 1 Then a.used_pages
                    When p.index_id < 2 Then a.data_pages
                    Else 0
                END
            ) * 8192 / 1024.,15,0)),
        ''indexes (kb)'' = ltrim(str((sum(a.used_pages)-sum(
                CASE
                    When a.type <> 1 Then a.used_pages
                    When p.index_id < 2 Then a.data_pages
                    Else 0
                END) )* 8192 / 1024.,15,0)),p.data_compression,
		p.data_compression_desc
        
    from sys.partitions p, sys.allocation_units a ,sys.sysobjects s
    where p.partition_id = a.container_id
        and p.object_id = s.id and s.type = ''U''    -- User table type (system tables exclusion)
    group by p.object_id,p.partition_id,p.partition_number,p.data_compression,p.data_compression_desc
    order by 3 desc'
;

Source: http://www.sqlservercentral.com/scripts/audit+tables+size/145975/