Dog Food Calculator
Work out how many calories and grams of food your dog or cat needs a day, from its weight, life stage and the food label.
An estimate for a healthy pet, based on the RER formula and factors in the Merck Veterinary Manual. Needs vary by up to 30%; weigh your pet regularly and ask your vet, especially for puppies, kittens, pregnant or ill animals and weight loss.
About this tool
Enter your pet's weight, choose dog or cat and life stage, and type in the calories per kg from the food bag. The calculator uses the veterinary resting energy formula (RER = 70 × weight^0.75) and the life-stage factors in the Merck Veterinary Manual to show daily calories, grams per day and per meal, a ±30% range and a treat allowance.
Frequently asked questions
Start from the resting energy requirement, 70 × body weight in kg^0.75, and multiply by a life-stage factor. A 20 kg neutered adult dog needs about 70 × 20^0.75 = 662 kcal at rest, × 1.6 = 1,059 kcal a day. With a dry food of 3,600 kcal/kg that is about 294 g a day, or 147 g in each of two meals.
The Merck Veterinary Manual uses 1.6 × RER for neutered adult dogs, 1.8 for intact adults, 1.4 for dogs prone to obesity, 3.0 for puppies under 4 months and 2.0 for older puppies. For cats it is 1.2 (neutered), 1.4 (intact), 1.0 (obesity prone) and 2.5 for kittens.
Complete pet foods state the energy content on the bag, usually in kcal per kg and often per cup. Wet food has far fewer calories per kg than dry food: the examples from Tufts University’s vet nutritionists are 3,606 kcal/kg for a dry dog food and 1,198 kcal/kg for a canned one, so the grams differ a lot.
Individual pets can need up to 30% more or less than the formula, according to the Merck Veterinary Manual. Weigh your pet every few weeks and adjust. Treats should be no more than 10% of daily calories (WSAVA), so take them off the food. Ask your vet about weight loss, pregnancy or illness.
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