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How many calories does a dog need per day?
Vets don't guess at this — they use a two-step formula. First a dog's resting energy needs, then a multiplier for life stage and activity. Here's how it works, with numbers you can check against your own dog.
Step 1: Resting Energy Requirement (RER)
RER is the energy a dog burns just existing — breathing, circulating blood, keeping warm — at rest. The standard formula is:
RER = 70 × (body weight in kg)0.75
That 0.75 power isn't arbitrary. Metabolism doesn't rise in a straight line with size — a small dog burns more energy per kilogram than a big one. Raising weight to the power of 0.75 captures that metabolic scaling, which is why the same formula (with a different constant) is used across mammals.
Step 2: Multiply by a life-stage factor
Resting needs are only part of the story. A growing puppy or a working sheepdog burns far more than a couch-loving senior. So RER is multiplied by a factor:
| Life stage | Factor × RER |
|---|---|
| Puppy, under 4 months | 3.0 |
| Puppy, 4–12 months | 2.0 |
| Neutered adult | 1.6 |
| Intact adult | 1.8 |
| Senior / less active | 1.2–1.4 |
| Weight loss (use ideal weight) | 1.0 |
| Very active / working | 2.0–5.0 |
Worked examples
Putting both steps together for a neutered adult:
| Weight | RER | × 1.6 = daily kcal |
|---|---|---|
| 5 kg | 234 | ~375 |
| 10 kg | 394 | ~630 |
| 20 kg | 662 | ~1,060 |
| 30 kg | 897 | ~1,440 |
It's a starting point, not a limit
Two dogs of identical weight can genuinely differ by 20% or more in what they need, thanks to breed, temperament and metabolism. So treat the number as a well-informed opening bid: feed it steadily for two to four weeks, watch your dog's body condition (ribs easily felt, visible waist from above), and nudge the amount up or down from there. And count treats toward the total — a good ceiling is 10% of daily calories.
Frequently asked questions
What's the formula for a dog's daily calories?
RER = 70 × (kg)0.75, then multiply by a life-stage factor (≈1.6 neutered adult, 1.8 intact, 2.0–3.0 puppy, 1.0 for weight loss at ideal weight).
How many calories does a 20 kg dog need?
About 1,060 kcal a day for a typical neutered adult (RER 662 × 1.6). Active or intact dogs of that weight need closer to 1,190–1,320 kcal.
Why weight to the power of 0.75?
Because metabolism scales sub-linearly with body size — small animals burn more per kilogram. The 0.75 exponent reflects that pattern, making the estimate accurate across very different dog sizes.