Dog Food Calculator
How many calories your dog needs a day, and how much of its food that is.
Good to know. The amounts on the bag are a starting point. Your dog’s waistline is the real feeding guide.
Approximate. Real-world values vary.
How it works
In plain words
A dog’s energy at rest is 70 times its weight in kilograms to the power 0.75. Multiply by the factor for its life stage, from 1.0 for weight loss to 3.0 for a young puppy, then divide by the calories in the food.
The formula
RER = 70 × kg^0.75 calories a day = RER × life-stage factor (1.6 for a neutered adult) food = calories ÷ kcal per cup (or × 100 ÷ kcal per 100 g)
Worked example
A neutered 20 kg dog rests on 70 × 20^0.75 ≈ 662 kcal, times 1.6 for 1,059 kcal a day. With food at 360 kcal per 100 g, that is about 294 g a day, or 147 g a meal.
Sources
- AAHA, 2021 Nutrition and Weight Management Guidelines for Dogs and Cats Resting energy requirement 70 × kg^0.75, and feeding for weight loss.
- Today’s Veterinary Nurse, Nutrition Math 101 Life-stage factors, such as 1.6 for a neutered adult dog and 3.0 for a puppy under 4 months.
Sources checked October 3, 2026. 3 automated tests check its answers on every change.
About the dog food calculator
Vets work out a dog’s food in two steps. First the resting energy requirement, what the body uses doing nothing: 70 times the weight in kilograms raised to the power 0.75, so a dog twice as heavy needs about 1.7 times as much, not twice. Then a factor for its life: 1.6 for a typical neutered adult, more for intact, young or working dogs, less for a lazy one or a diet.
The calories in dog food vary a lot, from under 300 to over 450 kcal per cup of dry food, and wet food has far fewer per gram. That is why the amount is worked out from the number on your bag rather than a generic cup.
Every dog is different, and these figures are estimates that can be 20% or more off for a given dog. Weigh your dog every few weeks and look at its shape: you should feel the ribs without pressing, and see a waist from above. Adjust the food by about 10% at a time. Treats count too, and should be under a tenth of the calories.
For weight loss, use the ideal weight and the losing-weight stage, and check with your vet. To convert your dog’s age, use the dog age calculator.
Questions people ask
How much should I feed my dog a day?
Work out its calories from weight and life stage, then divide by the calories in its food. A neutered 20 kg dog needs about 1,060 kcal, about 2.8 cups of a 380 kcal food.
How many calories does a dog need?
About 70 × kg^0.75 at rest, times 1.6 for a neutered adult. That is about 1,060 kcal for 20 kg and about 630 kcal for 10 kg.
How much should a puppy eat?
More per kilo than an adult: three times its resting need until 4 months, then twice until fully grown, split into three or four meals.