Dog Calorie Calculator — daily energy requirements (RER/MER)

RER (Resting Energy Requirement) is the number of calories a dog needs to sustain basic life functions at rest — essentially the dog equivalent of the human BMR. It is calculated using the allometric formula: RER = 70 × bodyweight_kg^0.75. For a 15 kg dog, RER ≈ 479 kcal/day. The exponent 0.75 means that larger dogs need proportionally fewer calories per kilogram than smaller dogs.

RER is the resting requirement, while MER (Maintenance Energy Requirement) is the total daily caloric need after accounting for activity, life stage and physiological status. MER = RER × life-stage factor. For a typical adult dog the factor is 1.4–1.8 depending on activity level, whereas puppies (2.8) and nursing dams (4.0) have much higher multipliers.

A 10 kg dog has an RER of approximately 394 kcal/day. At moderate activity (factor 1.6), MER ≈ 630 kcal/day. At low activity (1.4) ≈ 552 kcal, and at high activity (1.8) ≈ 709 kcal/day. A puppy at this weight would need roughly 1103 kcal/day (factor 2.8), and a nursing dam around 1577 kcal/day (factor 4.0).

A 30 kg dog has RER ≈ 883 kcal/day; at MER factor 1.6 that is ≈ 1413 kcal/day. A 40 kg dog has RER ≈ 1103 kcal; MER 1.6 ≈ 1765 kcal/day. Due to allometric scaling, large-breed dogs need fewer calories per kilogram than small-breed dogs — a factor that is especially important when calculating food portions.

A 3 kg dog has RER ≈ 178 kcal/day; at MER factor 1.6 that is ≈ 285 kcal/day. A 5 kg dog has RER ≈ 264 kcal; MER 1.6 ≈ 422 kcal/day. Small-breed dogs have a proportionally higher metabolic rate per kilogram of body weight compared to large breeds, so their daily portion is relatively larger.

The calculator estimates dry-food amount as MER ÷ 3500 kcal/kg, giving grams = MER ÷ 3.5. This assumes a typical dry food with about 3500 kcal/kg (3.5 kcal/g). Budget and economy kibbles often have lower density (~3200 kcal/kg) while premium or high-protein foods may reach 3800–4200 kcal/kg. Always check the specific product label and adjust accordingly.

The calculator estimates wet-food amount as MER ÷ 800 kcal/kg. Wet food typically contains 70–80% water, which is why portions are much larger than dry food. A dog needing 800 kcal/day would receive approximately 1000 g (1 kg) of wet food. Wet food can support hydration, which is particularly beneficial for dogs with kidney or urinary tract issues.

After neutering or spaying, a dog's resting metabolic rate typically decreases by 20–30%. The calculator uses a factor of 1.6 for neutered dogs — the same as a moderately active intact adult — which already reflects the lower need. Many veterinary nutritionists recommend reducing daily portions by 10–20% after the procedure and then monitoring body condition closely.

A pregnant dam's energy requirement increases progressively through gestation and the calculator applies a factor of 3.0 (MER = RER × 3). A nursing dam has the highest energy demands of any life stage — factor 4.0 — meaning she may need four times her resting caloric intake. High-quality puppy food or a performance diet is often recommended during this period.

The calculator uses a factor of 1.0 for obese dogs on a weight-loss programme, meaning MER equals RER calculated at the dog's current body weight. Safe weight loss is about 1–2% of body weight per week. Some veterinary guidelines recommend calculating RER based on the dog's ideal target weight rather than its current weight. Always involve a veterinarian when designing a weight-loss plan.