Oracle tablespace size sql

SELECT SUM(bytes) / (1024 * 1024*1024) AS free_space, tablespace_name
FROM dba_free_space
GROUP BY tablespace_name;

SELECT a.tablespace_name,
a.bytes/1024/1024/1024 total,
b.bytes/1024/1024/1024 used,
c.bytes/1024/1024/1024 free,
(b.bytes * 100) / a.bytes "% USED ",
(c.bytes * 100) / a.bytes "% FREE "
FROM sys.sm$ts_avail a, sys.sm$ts_used b, sys.sm$ts_free c
WHERE a.tablespace_name = b.tablespace_name
AND a.tablespace_name = c.tablespace_name;