Estimating total size of the database

I want to estimate a total size of the database prior to decomissioning.

So far I cam up with the following:

select (select sum(bytes)/(1024*1024) from dba_data_files)+
(select sum(bytes)/(1024*1024) from dba_temp_files) +
(select sum(bytes)/(1024*1024) redo_size from v$log ) +
(select sum(block_size*file_size_blks)/(1024*1024) controlfile_size from v$controlfile) "Size in MB" from dual;

Is that about orrect, or do i need to include anything else?