I don't know of any calculator but if you know consistently when you'd want to travel and what type of room you want it's just simply math. If you plan to go every year you need that many points. If you plan to go every other year you'd need 1/2 the number of points it costs to book the room for a week since you have twice as many points by pooling 2 years worth. If you go every 3rd year you'd need at least 1/3 the number of points (since you could access up to 3 years points). Often people will recommend a cushion in case of point reallocation (Disney can modify a resort's
point chart as long as they maintain the same number of total points for the resort). However my understanding is that AK CL rooms are extremely difficult to book as they are very few and they are extraordinarily popular. I personally have never tried to book one but have seen many posts that they can be difficult to even book right at 11 months. I don't think I would plan on consistently getting that particular booking especially if you aren't planning to buy AKL points.