Use the below SQL query to check the total, used and free space in all the tablespaces in the database

select 
   fs.tablespace_name                          "Tablespace", 
   (df.totalspace - fs.freespace)              "Used MB", 
   fs.freespace                                "Free MB", 
   df.totalspace                               "Total MB", 
   round(100 * (fs.freespace / df.totalspace)) "Pct. Free" 
from 
   (select 
      tablespace_name, 
      round(sum(bytes) / 1048576) TotalSpace 
   from 
      dba_data_files 
   group by 
      tablespace_name 
   ) df, 
   (select 
      tablespace_name, 
      round(sum(bytes) / 1048576) FreeSpace 
   from 
      dba_free_space 
   group by 
      tablespace_name 
   ) fs 
where 
   df.tablespace_name = fs.tablespace_name;

If you are running this in sqlplus you might want to format the columns first

column "Tablespace" format a13
column "Used MB" format 99,999,999
column "Free MB" format 99,999,999
column "Total MB" format 99,999,999