By useing the canine pregnancy calander its says this by putting in her tie date as Aug 2
Fri 5 Oct 2007 Expected date of whelp. Of course this is just an average. Whelping may take place from the 59th to the 65th day. Puppies born before the 58th day will probably be too young to survive.
http://www.debbiejensen.com/date.html