I found this on Toadworld:
http://www.toadworld.com/platforms/oracle/w/wiki/4887.script-to-report-tablespacedatafile-space-utilization.aspx
There are lots of useful scripts there: http://www.toadworld.com/platforms/oracle/w/wiki/4861.instant-scripts.aspx
I've changed a couple of the column formats from the original.
REM LOCATION: Object Management\Tablespaces and DataFiles\Reports
REM FUNCTION: Generate a report of Tablespace Space Availability
REM including autoextend related space availability.
REM
REM TESTED ON: 10.2.0.3 and 11.1.0.6
REM PLATFORM: non-specific
REM REQUIRES: dba_tablespaces, dba_data_files
REM
REM This is a part of the Knowledge Xpert for Oracle Administration library.
REM Copyright (C) 2008 Quest Software
REM All rights reserved.
REM
REM ******************** Knowledge Xpert for Oracle Administration ********************
SET lines 160 pages 66 feedback off
COLUMN tablespace_name format a20 heading 'Tablespace|(TBS)|Name'
COLUMN autoextensible format a6 heading 'Can|Auto|Extend'
COLUMN files_in_tablespace format 999 heading 'Files|In|TBS'
COLUMN total_tablespace_space format 99,999,999,999,999 heading 'Total|Current|TBS|Space'
COLUMN total_used_space format 99,999,999,999,999 heading 'Total|Current|Used|Space'
COLUMN total_tablespace_free_space format 99,999,999,999,999 heading 'Total|Current|Free|Space'
COLUMN total_used_pct format 999.99 heading 'Total|Current|Used|PCT'
COLUMN total_free_pct format 999.99 heading 'Total|Current|Free|PCT'
COLUMN max_size_of_tablespace format 99,999,999,999,999 heading 'TBS|Max|Size'
COLUMN total_auto_used_pct format 999.99 heading 'Total|Max|Used|PCT'
COLUMN total_auto_free_pct format 999.99 heading 'Total|Max|Free|PCT'
TTITLE left _date center Tablespace Space Utilization Status Report skip 2
WITH tbs_auto AS
(SELECT DISTINCT tablespace_name, autoextensible
FROM dba_data_files
WHERE autoextensible = 'YES'),
files AS
(SELECT tablespace_name, COUNT (*) tbs_files,
SUM (BYTES) total_tbs_bytes
FROM dba_data_files
GROUP BY tablespace_name),
fragments AS
(SELECT tablespace_name, COUNT (*) tbs_fragments,
SUM (BYTES) total_tbs_free_bytes,
MAX (BYTES) max_free_chunk_bytes
FROM dba_free_space
GROUP BY tablespace_name),
AUTOEXTEND AS
(SELECT tablespace_name, SUM (size_to_grow) total_growth_tbs
FROM (SELECT tablespace_name, SUM (maxbytes) size_to_grow
FROM dba_data_files
WHERE autoextensible = 'YES'
GROUP BY tablespace_name
UNION
SELECT tablespace_name, SUM (BYTES) size_to_grow
FROM dba_data_files
WHERE autoextensible = 'NO'
GROUP BY tablespace_name)
GROUP BY tablespace_name)
SELECT a.tablespace_name,
CASE tbs_auto.autoextensible
WHEN 'YES'
THEN 'YES'
ELSE 'NO'
END AS autoextensible,
files.tbs_files files_in_tablespace,
files.total_tbs_bytes total_tablespace_space,
(files.total_tbs_bytes - fragments.total_tbs_free_bytes
) total_used_space,
fragments.total_tbs_free_bytes total_tablespace_free_space,
( ( (files.total_tbs_bytes - fragments.total_tbs_free_bytes)
/ files.total_tbs_bytes
)
* 100
) total_used_pct,
((fragments.total_tbs_free_bytes / files.total_tbs_bytes) * 100
) total_free_pct,
AUTOEXTEND.total_growth_tbs max_size_of_tablespace,
( ( ( AUTOEXTEND.total_growth_tbs
- (AUTOEXTEND.total_growth_tbs - fragments.total_tbs_free_bytes
)
)
/ AUTOEXTEND.total_growth_tbs
)
* 100
) total_auto_used_pct,
( ( (AUTOEXTEND.total_growth_tbs - fragments.total_tbs_free_bytes)
/ AUTOEXTEND.total_growth_tbs
)
* 100
) total_auto_free_pct
FROM dba_tablespaces a, files, fragments, AUTOEXTEND, tbs_auto
WHERE a.tablespace_name = files.tablespace_name
AND a.tablespace_name = fragments.tablespace_name
AND a.tablespace_name = AUTOEXTEND.tablespace_name
AND a.tablespace_name = tbs_auto.tablespace_name(+);
