You'll never buy box mix again. :) This recipe courtesy of Marlene Gaffner.
1 1/4 C flour
1T baking powder
1/2 t salt
1 C milk
I mix up a couple recipes of the dry ingredients in a big ziplock bag and then keep it in the fridge. When I want to make pancakes, then it is just 1 1/3 c of the dry ingredients mixed with the egg, milk, and oil. If I'm making a lot of pancakes, I make up milk from powdered milk (usually in a nalgene bottle) and that works great!
I usually make 4 batches at once, which makes 5 cups of flour. I usually make one of those cups whole wheat flour. That seems to be about right for my tastes.