You have to go by the individual dog and his body condition. There is no set formula. As long as your dog is lean, ribs can be easily felt, with a waist (not all dogs have a tuck..mine has more now, but had hardly any when younger). My pup right now (8 months old) eats 6-7 cups a day. He's nice and lean. Another dog might be hugely overweight on the same feeding regimen. Varik would be emaciated on 3 cups a day (which I've seen many people feed).
Xan Varik von Fernheim (born 4/3/13)