View free space on Oracle tablespaces

SQL query, which could be used for listing tablespaces and occupied space:

select df.tablespace_name "Tablespace", totalusedspace "Used MB", (df.totalspace - tu.totalusedspace) "Free MB", df.totalspace "Total MB", round(100 * ( (df.totalspace - tu.totalusedspace)/ df.totalspace)) "Pct. Free" from (select tablespace_name, round(sum(bytes) / 1048576) TotalSpace from dba_data_files group by tablespace_name) df, (select round(sum(bytes)/(1024*1024)) totalusedspace, tablespace_name from dba_segments group by tablespace_name) tu where df.tablespace_name = tu.tablespace_name ;