Query to check Tablespace Size and Available Freespace in Oracle

SELECT b.tablespace_name, NVL(tbs_size,0) tablespace_Size_in_mb, NVL(a.free_space,0) available_free_in_mb
  FROM (  SELECT tablespace_name,
                 ROUND (SUM (bytes) / 1024 / 1024, 2) AS free_space
            FROM dba_free_space
        GROUP BY tablespace_name) a,
       (  SELECT tablespace_name, SUM (bytes) / 1024 / 1024 AS tbs_size
            FROM dba_data_files
        GROUP BY tablespace_name
        UNION
          SELECT tablespace_name, SUM (bytes) / 1024 / 1024 tbs_size
            FROM dba_temp_files
        GROUP BY tablespace_name) b
 WHERE a.tablespace_name(+) = b.tablespace_name
      AND b.tablespace_name = '<<Tablespace_Name>>'