Pet food quantity - large package or small package?

Well, we don't purchase the big ones because we find it a waste. Our cats' food usually lasts a month, therefore, when the cat food is done there is a sale across the street for cat food.

I tend to give the cats portions as opposed to my fiancee, who fills the entire bowl up. Only if the big bag is the same price as the smaller bag then I will purchase it, but if it isn't then we'll just stick to the bag we buy every month or so.