Calories are the foundation of everything else

Every feeding decision — how much kibble, how many treats, whether your dog is gaining or losing weight — comes back to one number: daily calories. This calculator gives you that number, and shows its working, so you can use it everywhere else. The method is the same one veterinary nutritionists use. First, the resting energy requirement: RER = 70 × (body weight in kg)^0.75. That is the calories your dog burns at rest, doing nothing. Then the activity factor: 3.0 for puppies under four months, 2.0 for older puppies, 1.8 for intact adults, 1.6 for neutered adults, 1.2 for inactive or senior dogs, 1.0 for vet-guided weight loss and about 2.2 for active or working dogs. Multiply the two and you have the estimated daily calorie need. For a ten-kilogram neutered adult dog, that is 394 × 1.6 ≈ 630 kcal a day — the worked example on this page.

The table on this page shows the same weight at every life stage, which is useful because it makes the differences visible. A ten-kilogram puppy under four months needs about 1,180 kcal a day — nearly twice what the same dog needs as a neutered adult. An intact adult needs about 710, a senior about 470, and a dog on a weight-loss plan about 394. That is why a single "how much should my dog eat" answer is meaningless without the life stage: the same dog, at the same weight, needs anywhere from 400 to 1,200 kcal a day depending on its age, neuter status and activity. If you have ever wondered why your puppy seems hungry all the time, or why your neutered dog gained weight on the same food, this table is the answer.

How to use the number

Once you have the daily calorie figure, everything else is arithmetic. Divide it by the kcal per cup on your food bag to get cups per day; divide it by the kcal per can to get cans per day; take ten percent of it to get the treat budget. Weigh the food rather than scooping it — a cup of kibble can vary by fifty percent in weight depending on kibble size and packing. Then watch the result for two to four weeks: weigh your dog on the same scales, feel the ribs, and look at the waist from above. If the weight is stable and the body condition is ideal (BCS 5), the number is right. If your dog is gaining, cut by about ten percent; if losing, add ten percent. Change one thing at a time and give it time — a dog's weight responds slowly, and changing the amount every few days tells you nothing.

What affects the result

Weight is the biggest input, and it should be the target weight if your dog is overweight — feeding for the current weight maintains the overweight. Neutering lowers the factor from 1.8 to 1.6, which is about an eleven percent reduction, and that alone explains most post-neutering weight gain. Activity is the most variable factor: a working dog can need a factor of 2.5 or more, while a couch dog may need only 1.2. Temperature matters too — dogs burn more calories in cold weather. Illness changes the picture entirely: a dog with kidney disease, pancreatitis, diabetes or cancer needs a diet and a calorie level set by its vet, and this calculator is not a substitute for that. Puppies of large and giant breeds are a special case: overfeeding a growing large-breed puppy increases the risk of skeletal disease, so the factor for them should be set with your vet.

Common mistakes

The most common mistake is using the feeding guide on the bag as if it were a prescription — bag guides are generous ranges for an average dog. The second is forgetting treats, which can be twenty percent or more of a small dog's intake. The third is feeding for the dog's current weight when it is overweight, which locks the weight in place. The fourth is cutting calories too hard: a factor below 1.0 without veterinary supervision risks nutritional deficiency, and in any case a safe weight-loss rate is one to two percent of body weight per month. The fifth is assuming the number is exact — it is an estimate, and the only way to know it is right for your dog is to watch the weight and body condition over a few weeks.

When to see a vet

See your vet before changing calories if your dog is losing or gaining weight quickly, has a medical condition, is a large-breed puppy, or is pregnant or nursing. If your dog is overweight, ask your vet to set a target weight and a calorie plan — the dog ideal weight calculator can help you see the target, but the plan should be your vet's. Use the dog food calculator to turn the calorie figure into cups and grams, the treat calorie calculator to work out how many treats fit in the budget, and the dog BMI calculator for a second check on body condition.