Dog Food Portion Calculator
Inputs
| Body weight | 15 kg |
|---|---|
| Life stage | Neutered adult |
| Food energy density | 350 |
Dog Food Portion Calculator
Estimate a dog’s daily calorie requirement and dry-food portion in cups using the RER/MER method, based on body weight and life stage.
Inputs
Results
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Details
A 15 kg Neutered adult dog needs about ... per day — roughly ... cups of food at your bag’s calorie density.
How much a dog should eat depends on body weight, life stage, and the calorie density of the food. The method used here — resting energy requirement scaled by a life-stage factor — is the basis of the feeding recommendations published by the World Small Animal Veterinary Association (WSAVA) and the National Research Council (NRC). The result is a starting estimate; body-condition scoring over two to four weeks is the practical way to confirm the right amount.
The RER formula
Resting Energy Requirement (RER) is the number of calories a dog burns at complete rest to keep basic body functions running. It is calculated from metabolic body weight, which scales by the 0.75 power rather than linearly:
The 0.75 exponent reflects the fact that larger animals have a lower metabolic rate per kilogram than smaller ones. A 30 kg dog does not need twice as many calories as a 15 kg dog at rest — it needs roughly 1.68 times as many.
Life-stage multipliers
Maintenance Energy Requirement (MER) adjusts RER upward or downward depending on the dog's life stage and reproductive status:
| Life stage | Factor |
|---|---|
| Neutered adult | 1.6 |
| Intact adult | 1.8 |
| Weight loss | 1.0 |
| Active / working | 2.5 |
| Puppy (growing) | 3.0 |
| Senior | 1.4 |
Puppies need disproportionately more energy per kilogram because they are building muscle, bone, and organ tissue. Working dogs — sled dogs, herding breeds in active work — can need two and a half times their resting requirement. Weight-loss programs use an MER equal to RER (factor 1.0), which means the dog is fed at its bare maintenance floor to create a gentle deficit.
Converting calories to cups
Most dry kibble bags list kilocalories per cup in the feeding guide or guaranteed analysis panel. Dividing MER by that density gives the number of cups per day:
Calorie density varies widely — from roughly 300 kcal/cup for low-density weight-management foods to over 500 kcal/cup for high-fat performance formulas. Using the wrong figure, or a generic average, will give an inaccurate portion.
Worked example
A 15 kg neutered adult dog fed a food with 350 kcal/cup:
RERMERcups/day=70×150.75=70×7.622=533.6 kcal=533.6×1.6=853.7 kcal=350853.7≈2.4 cupsThat 2.4 cups is a starting point. If the dog's ribs become easy to feel but hard to see and the waist is visible from above, the amount is about right. If ribs are hard to feel or the dog looks rounder week over week, reduce slightly. If the dog appears thin, increase.
Limitations
This formula assumes the dog is healthy and at a stable adult weight. Pregnant, lactating, and growing dogs have considerably higher requirements than the adult multipliers suggest. Dogs with thyroid disease, Cushing's syndrome, or other metabolic conditions may need substantially different amounts. For those cases, a veterinarian's guidance takes precedence over any formula.
To look up your dog's age in human years, see the Dog Age Calculator.
Frequently Asked Questions (FAQ)
How many calories does my dog need per day?
Most adult dogs need between 25 and 35 kcal per kilogram of body weight per day, depending on whether they are neutered, their age, and their activity level. The RER/MER method gives a more precise figure by raising body weight to the 0.75 power (metabolic body weight) and then multiplying by a life-stage factor. A 15 kg neutered adult, for example, works out to roughly 854 kcal/day. These are starting estimates; body-condition scoring over two to four weeks is the practical way to confirm the right amount.
What is RER and how does MER differ?
RER (Resting Energy Requirement) is the energy a dog burns at complete rest to keep organs and systems running. It is calculated as 70 × kg^0.75. MER (Maintenance Energy Requirement) is RER scaled up by a life-stage factor to account for growth, reproduction, activity, or the lower metabolism of neutered or senior animals. The factors used here follow the WSAVA/NRC guidelines: 1.6× for neutered adults, 1.8× for intact adults, 1.0× for weight loss, 2.5× for active or working dogs, 3.0× for puppies, and 1.4× for seniors.
How do I convert calories to cups of food?
Divide the daily calorie target by the kilocalories per cup printed on your food bag. For example, 854 kcal ÷ 350 kcal/cup ≈ 2.4 cups. The kcal/cup value is usually found in the guaranteed analysis or the feeding guide on the back of the bag. Different brands and formulas vary widely — from about 300 to more than 500 kcal/cup — so always use the figure from your specific product rather than a generic average.
Disclaimer
This calculator provides an estimate based on the standard RER/MER formula and is not veterinary advice. Individual dogs vary in metabolism, health status, and activity. Consult your veterinarian before adjusting food intake, especially for puppies, pregnant or lactating dogs, dogs with medical conditions, or dogs that need to lose or gain weight. Always check the kcal/cup figure on your specific food bag.
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