select vsize(sysdate) from dual

SQL> select vsize(hiredate) from emp;

VSIZE(HIREDATE)
---------------
              7

select vsize(to_date('01-jan-2007')) from dual

select distinct data_length,default_length from dba_tab_columns where data_type='DATE' SQL> ;

DATA_LENGTH DEFAULT_LENGTH
----------- --------------
          7              4
          7              8
          7             18
          7
          8
          7              7
          7              5
          7              9

8 rows selected.

FOO SCOTT>select vsize(to_date('01-jan-2007')) from dual;
select vsize(to_date('01-jan-2007')) from dual
                     *
ERROR at line 1:
ORA-01858: a non-numeric character was found where a numeric was expected

  1* select vsize(to_date('01-jan-2007','dd-mon-yyyy')) from dual
SQL> /

VSIZE(TO_DATE('01-JAN-2007','DD-MON-YYYY'))
-------------------------------------------
                                          7

SQL> ed
Wrote file afiedt.buf

  1* select vsize(sysdate) from dual
SQL> /

VSIZE(SYSDATE)
--------------
             7

Connected to:
Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production

SQL> select to_date('01-jan-2007') from dual;

TO_DATE('
---------
01-JAN-07

SQL> select vsize(to_date('01-jan-2007')) from dual;

VSIZE(TO_DATE('01-JAN-2007'))
-----------------------------
                            8