PHP >= 5.3.0
# object oriented
$from = new DateTime('1970-02-01');
$to = new DateTime('today');
echo $from->diff($to)->y;
# procedural
echo date_diff(date_create('1970-02-01'), date_create('today'))->y;
functions: date_create()
, date_diff()
solved How to get user date of birth from a form then get the user age in php mysql