Calculate Tablespace Sizes

SELECT df.tablespace_name "Tablespace"
,round((sum(nvl(fs.bytes,0))/ (df.bytes)) * 100)
"%Free"
,round(((df.bytes - sum(nvl(fs.bytes,0)))
/ (df.bytes) ) * 100) "%Used"
,round(sum(nvl(fs.bytes/1024/1024,0))) "Mb Free"
,round(df.bytes/1024/1024
- sum(nvl(fs.bytes/1024/1024,0))) "Mb Used"
FROM dba_free_space fs, dba_data_files df
WHERE fs.file_id(+) = df.file_id
GROUP BY df.tablespace_name, df.file_id, df.bytes,
df.autoextensible
ORDER BY df.file_id;