Baked Potatoes

I always bake too many potatoes and we never eat the left overs. They sit in the fridge for a few weeks, waiting patiently for anyone to consume them, and then I throw them away. I usually bake just one too many. It's hard to judge when there's one hungry husband, and yourself ( sometimes, or often times--do I dare to admit?--I can out-eat Spencer), AND two half-people that occasionally have growth spurts or occasionally have no appetite. So, how many potatoes do I cook? Sometimes I think I get the number right, but then I forget to take into account that the potatoes are enormous and one person can't possibly eat the whole thing. I know potato calculation is not calculus, but I sure can't get it right.
love,
Sarah