How to calculate how many calories your dog needs

Step 1: resting energy (RER)

RER is the energy a dog burns at rest in a comfortable room: breathing, digestion, keeping warm. The Merck Veterinary Manual gives it as 70 times body weight in kilograms raised to the power 0.75. The 0.75 exponent is there because energy use doesn’t rise in a straight line with weight: a 60 lb dog needs much less than twice the calories of a 30 lb dog.

1. Convert pounds to kilograms: divide by 2.2. A 30 lb dog is about 13.6 kg.
2. Raise the kilograms to the power 0.75. On a phone calculator, type 13.6, then the xʸ key, then 0.75. You get about 7.1.
3. Multiply by 70. That gives an RER of about 496 kcal a day.

You may also see a shortcut, 30 × kg + 70. It is close for mid-sized dogs, but it drifts at the small and large ends, so we don’t use it.

Step 2: multiply by a life-stage factor (MER)

The maintenance energy requirement, MER, is RER times a factor for your dog’s life stage and activity. Here are the factors the main references use for dogs.

Worked examples

For a growing puppy, use its current weight, not its expected adult weight, and the puppy factor. A 10 lb puppy older than 4 months: RER 218 × 2.0 is about 436 kcal a day, and it will need more as it grows. The National Research Council’s owner brochure makes the same point another way: puppies need about twice the calories per pound of adult dogs of the same breed.

Step 3: turn calories into cups

Find the kcal per cup (or per can) on your dog food bag, usually printed near the guaranteed analysis as “kcal/cup” or “kcal ME/cup”. Divide the daily calories by that number. A 30 lb neutered adult at 794 kcal, eating a food with 380 kcal per cup, needs about 2.1 cups a day. Remember to count treats: if they add up to a noticeable share of the day, take them off the meal.

Why your dog may need more or less

Every one of these numbers is an average. The Pet Nutrition Alliance notes that individual dogs can differ by as much as 50% from the predicted value, and AAHA calls the life-stage factors general guidelines. Indoor and quiet dogs often need less. The NRC brochure says older dogs need about 20% fewer calories than younger adults. Working dogs and dogs in hard training can need several times more.

So the real test is the scale and your hands. Weigh your dog every two to four weeks after changing the amount. On the WSAVA body condition chart, an ideal dog has ribs you can feel without excess fat and a visible waist behind the ribs when seen from above. If the weight keeps creeping up or the waist disappears, adjust the amount and ask your vet how big a change to make.

The dog food calculator does all three steps for you and shows a range instead of one number, so you can see how much the choice of factor matters. For puppies, the puppy feeding chart also covers how many meals a day by age.