set linesize 200
set pages 40
--
break on report
compute sum of tot_GB tot_freeGB on report
col tablespace_name format A30 heading tablespace
col tot_GB format 999,999,999,999.99
col tot_freeGB format  999,999,999.99
col Kb_max format  999,999,999

select f.tablespace_name
      ,f.bytes/1024/1024/1024 tot_GB
      ,sum(nvl(s.bytes,0)/1024/1024/1024) tot_freeGB
      ,max(nvl(s.bytes,0)/1024) maxextent_freeKB
      ,( (sum(nvl(s.bytes,0)/1024/1024/1024)) / (f.bytes/1024/1024/1024) )*100 Pct_available
from   dba_data_files f
      ,dba_free_space s
where  f.file_id = s.file_id(+)
group by f.tablespace_name, f.bytes/1024/1024/1024
order by 2 desc ;