Dog Food Calculator
Work out your dog's daily portion: the veterinary RER formula gives resting calories, a life-stage factor scales it, and the kcal-per-cup number from your food's bag turns it into cups per day. Every step is shown — including why the same dog needs different amounts of different foods.
A starting point, not a prescription: confirm amounts with your vet and the bag's feeding guide, and adjust to your dog's body condition.
The veterinary feeding math
Vets start from the resting energy requirement: RER = 70 × (weight in kg)^0.75 — the ¾-power is Kleiber's law, which holds across mammals from mice to mastiffs. A life-stage factor then scales it: ~1.6 for a neutered adult, 1.8 intact, 2–3 for puppies, ~1.0 for vet-guided weight loss.
Cups come from YOUR food's energy density — the "kcal ME/cup" printed on every bag (typically 300–450). That's why cup recommendations differ between brands for the same dog, and why switching foods without recalculating quietly over- or underfeeds.
Worked examples
Example 1: 50 lb neutered adult
Typical 350 kcal/cup kibble — cups per day?
- Weight to kg and RER.22.7 kg → 70 × 22.7^0.75 ≈ 727 kcal
- Neutered-adult factor.727 × 1.6 ≈ 1,164 kcal/day
- Divide by the bag's kcal per cup.1,164 ÷ 350 ≈ 3.3 cups
About 3⅓ cups a day, usually split into two meals.
Example 2: same dog, different food
Switching to a dense 450 kcal/cup formula.
- The dog's calorie need doesn't change.still 1,164 kcal/day
- Only the divisor changes with the denser food.1,164 ÷ 450 ≈ 2.6 cups
Portions drop by almost a cup — skip this recalculation and the dog gains weight on the "same" scoops.
Example 3: growing puppy
A 20 lb puppy, 5 months old, 380 kcal/cup puppy food.
- RER for 9.1 kg.70 × 9.1^0.75 ≈ 366 kcal
- Older-puppy factor ×2.732 ÷ 380 ≈ 1.9 cups
About 2 cups a day across 3 meals — and the number changes as the puppy grows, so recalc monthly.
FAQ
Why does this differ from the chart on the bag?+
Bag charts bracket wide weight ranges and assume average activity; the RER route computes your dog's point estimate. They usually land close — when they don't, start between the two and adjust by body condition.
How do I know my food's kcal per cup?+
It's legally printed on the label: look for "kcal ME/cup" (or per kg) near the guaranteed analysis. Typical dry foods run 300–450 kcal/cup; puppy and performance formulas sit higher.
How do treats fit the math?+
The 10% rule: treats should stay under 10% of daily calories, and the main food shrinks accordingly. A 30-kcal biscuit is noise for a Lab and a meal for a Chihuahua.
How do I tell if the amount is right?+
Body condition beats math: ribs easy to feel but not see, visible waist from above. Vets score it 1–9 (4–5 ideal) — adjust portions ±10% every few weeks toward that, not toward the calculator.
Is this veterinary advice?+
No — standard healthy-dog formulas as a starting point. Puppies of giant breeds, pregnant or nursing dogs, and dogs with medical conditions need a vet-designed plan.
Related calculators
- Puppy Weight CalculatorEstimate your puppy's adult weight from its current weight, age and expected size class, using the published milestone rules — with the math and caveats shown.
- Dog Age CalculatorConvert dog years to human years with the veterinary size chart and the UCSD epigenetic formula — not the old times-7 myth. Steps included.