The weeks_between() function determines the truncated number of full weeks between two timestamps.
int = weeks_between(timestamp t1, timestamp t2);
The t1 value specifies the beginning timestamp.
The t2 value specifies the ending timestamp.
select weeks_between('1996-02-27 06:12:33' , '1996-03-05 07:12:33');
WEEKS_BETWEEN
---------------
1
(1 row)