If you log onto the
DVC member website, click on "My Vacation Points" under the "My Membership" heading. The first screen that comes up has a heading "Alerts" under which it has the dates that you can book a cruise, reserve at your home resort and reserve at all other resorts. It also tells you when your current year's points will expire. Today it says that you can book a vacation at any DVC resort (i.e. 7 month window) that has a check-out date before April 17, 2008. So, it's not really a calculator that into which you enter your information. It's more of a booking guideline. Hope this helps!