How to find the size of a Oracle 11g table

Question

I want to find the size of a table in Oracle 11g.
I hope, my question is clear.
Please revert with the reply to my query.
Regards

Answer 1

--- List all tables sorted by size
set lines 100 pages 999
col     segment_name     format a40
col      mb           format 999,999,999
select     segment_name
,     ceil(sum(bytes) / 1024 / 1024) "MB"
from     dba_segments
where     segment_type = 'TABLE'
group     by segment_name
order      by ceil(sum(bytes) / 1024 / 1024) desc
--- List all tables owned by a user sorted by size
set lines 100 pages 999
col     segment_name     format a40
col      mb           format 999,999,999
select     segment_name
,     ceil(sum(bytes) / 1024 / 1024) "MB"
from     dba_segments
where     owner like '&user'
and     segment_type = 'TABLE'
group     by segment_name
order      by ceil(sum(bytes) / 1024 / 1024) desc
/