How much should I feed a 100 lb dog?

A 100 lb dog weighs about 45.4kg, giving a resting energy of around 1,224 kcal, and a typical neutered adult at normal activity needs close to 1.6 times that, about 1,960 kcal a day. At 350 to 400 kcal per 100g of a standard dry food, that lands near 515 to 540g.

A higher calorie formula, often 420 to 450 kcal per 100g, brings that volume down to roughly 435 to 465g while providing the same total energy.

A denser, higher calorie food suits a dog that struggles to eat enough volume comfortably in one sitting, while a standard density food gives more bowl volume for the same calories, which some owners feel helps a dog feel satisfied.

Neither is inherently better, and the right choice depends on your dog's appetite and how your vet feels about your dog's current body condition.

Weigh your dog every four to six weeks, ideally at your vet clinic if a home scale does not handle this weight reliably.

Feel the ribs and waist regularly between weigh ins, since a slow gain across a big frame is easy to miss by sight alone. A written log comparing weight across several months is far more useful for spotting a slow trend than comparing two readings taken only weeks apart, especially on a frame this size where a modest gain is easily missed.