I used to have 6 cats but even now with only 5 I don't see much of a difference. I buy Innova Evo in the largest bags which is a little over 15lbs. They last me about 1 month or so. I think it's because I feed Storm a lot of canned food so he doesn't eat as much of the dry as the others do. They eat about 1/2 cup or a bit less a day and now I'm also giving all of them some canned at night. I'm always buying at least 2 bags at once so I don't have to go to the pet store so often.