How to check the single table size in oracle11g

By using this query we can able to find the table size by below mentioned table format
owner.tablename. Eg - hr.employees

query:

select segment_name,segment_type, sum(bytes/1024/1024/1024) GB
 from dba_segments
 where segment_name='&Your_Table_Name' 
group by segment_name,segment_type;