Get oracle table size

http://stackoverflow.com/questions/264914/how-do-i-calculate-tables-size-in-oracle

--first gather stats for table...
begin
 dbms_stats.gather_table_stats('MYSCHEMA','MYTABLE');
end;
--or schema...
begin
 dbms_stats.gather_table_stats('MYSCHEMA');
end;

--get table size
select
 owner,
 table_name,
 round((num_rows*avg_row_len)/(1024*1024)) MB,
 num_rows,
 avg_row_len,
 last_analyzed
from
 all_tables
where
 owner = '<WHOEVER>' and
 table_name in ('<WHATEVER>')
order by
 MB desc

Also need to determine size of indexes seperately.