The answer, in one line
A dog's daily energy need is its resting energy requirement multiplied by one factor. Resting energy is RER = 70 × (weight in kg)0.75. Multiply that by 1.6 for a neutered adult, 1.8 for an intact adult, 3.0 for a puppy under four months or 2.0 for an older puppy, and you have the calories to feed. Everything else on this page is just turning that number into grams of your actual food and checking what those grams contain.
How the nutrition check works
Calories tell you how much to feed. They say nothing about whether that amount carries enough protein or fat. So this page does the second step the calorie-only tools skip:
grams of food per day = daily kcal ÷ (kcal per kg of food) × 1000
protein per day (g) = grams of food × protein % ÷ 100
fat per day (g) = grams of food × fat % ÷ 100
The minimums come from the AAFCO Dog Food Nutrient Profiles. On a dry-matter basis, adult maintenance requires at least 18% crude protein and 5.5% crude fat; growth and reproduction — which is what a puppy is on — requires at least 22.5% protein and 8.5% fat. This page converts those to grams for the portion you are actually feeding, assuming dry food at about 90% dry matter, so you can compare the floor against what your bag supplies.
Those numbers are floors, not targets. AAFCO minimums exist to prevent deficiency in a population of dogs; they are not a performance optimum, and a working or heavily exercised dog is routinely fed well above them. Use them to catch a food that is short, not to choose between two good foods.
Reading a dog food label without getting fooled
Three things on the bag matter here, and two of them are easy to misread.
Calorie content. Usually printed as kcal/kg or kcal per cup, and often buried near the ingredient list rather than in the nutrition panel. If your bag only gives kcal per cup, weigh one level cup in grams and work it out: kcal per kg = kcal per cup × 1000 ÷ grams per cup. Cups are not a unit of mass, which is why the gram figure is the one worth having.
Guaranteed analysis. These percentages are as-fed, meaning they include the water in the food. A canned food at 78% moisture and a dry food at 10% moisture can show the same protein percentage while delivering very different amounts per calorie. To compare them, convert to dry matter: dry-matter protein % = as-fed protein % × 100 ÷ (100 − moisture %).
"Complete and balanced." That statement means the food meets an AAFCO profile for a stated life stage. If it does not say which life stage, or if it says "for intermittent or supplemental feeding only", it is not a complete diet and the minimums above do not apply to it.
Where this estimate breaks down
The same limits that apply to any calorie estimate apply here, and one extra. Individual dogs vary from the predicted value by as much as 50%, so the calorie figure is a starting point to be tested against body condition over a fortnight, not a prescription. The protein and fat figures inherit that uncertainty and add their own: they assume the guaranteed analysis is accurate to the printed figure, and they assume a dry-matter content of about 90%. A food with an unusual moisture content will shift them. If your dog has kidney, liver or pancreatic condition, or any other clinically managed problem, the numbers here are not the ones your vet is working from.
Frequently asked questions
Is a dog nutrition calculator different from a dog calorie calculator?
A calorie calculator stops at energy. A nutrition calculator takes the same energy number and asks what that portion of food actually contains in protein and fat, then compares it with the published minimums. The calorie figure is identical; the extra step is the nutrition check.
How much protein does a dog need per day?
For adult maintenance the floor is 18% crude protein on a dry-matter basis; for growth and reproduction it is 22.5%. Converted into grams, that depends entirely on how much food the dog eats, which is why the calculator above works it out from your portion rather than quoting a single number.
Why does my bag show a lower protein percentage than another brand but still meet the minimum?
Because the guaranteed analysis is as-fed. A high-moisture food shows lower percentages for everything simply because more of its weight is water. Compare foods on a dry-matter basis, or compare grams of protein per 100 kcal, and the ranking often changes.
Do puppies and adults need different protein?
Yes. Growth and reproduction carries higher minimums — 22.5% protein and 8.5% fat on a dry-matter basis, against 18% and 5.5% for adult maintenance. A puppy fed an adult-maintenance food can meet the calorie number and still fall short on the nutrient side.
Should I feed more protein to an active dog?
Energy is the first thing to raise, not protein. An active dog on an adult food with a higher activity factor eats more total food, and the extra protein comes along with it. Protein becomes the thing to look at when the dog is eating little for its size, or is on a restricted-calorie weight-loss plan where the portion shrinks but the nutrient requirement does not.
Does this replace a veterinary diet plan?
No. These are population-level minimums and a population-level energy estimate. Therapeutic diets, puppies with growth abnormalities, and dogs with organ disease all need individual calculation by a vet.
Sources
- Energy factors RER 70 × kg0.75 and the maintenance multipliers — MSD Veterinary Manual, caloric requirements of adult dogs.
- Protein and fat minimums — AAFCO Dog Food Nutrient Profiles, adult maintenance and growth/reproduction.
- Body condition scoring context — WSAVA Global Nutrition Guidelines.
Need the pure calorie version with the portion in cups? Use the dog calorie calculator on the home page.