Script to check database size

SELECT dd.tablespace_name tablespace_name, dd.file_name file_name, dd.bytes/1024 TABLESPACE_KB, SUM(fs.bytes)/1024 KBYTES_FREE, MAX(fs.bytes)/1024 NEXT_FREE
FROM sys.dba_free_space fs, sys.dba_data_files dd
WHERE dd.tablespace_name = fs.tablespace_name
GROUP BY dd.tablespace_name, dd.file_name, dd.bytes/1024
ORDER BY dd.tablespace_name, dd.file_name;