Pet Calorie Needs Calculator
Calculate your pet's Resting Energy Requirement (RER) and daily calorie need (MER) for dogs and cats of any size.
How to use this tool
- Weigh your pet accurately.
- Select the species and life stage.
- The RER is the baseline calories needed at rest; MER is the adjusted daily target.
Use this calculator to find the daily calorie needs of any dog or cat based on their weight, species, and life stage.
Not veterinary advice. These results are estimates for general guidance only. Always consult a licensed veterinarian before making health, nutrition, or medication decisions for your pet.
Formula
Resting Energy Requirement: RER = 70 × weight(kg)0.75 kcal/day
Maintenance Energy Requirement: MER = RER × life_stage_factor
Dog factors: puppy 3.0 · adult neutered 1.6 · adult intact 1.8 · active 2.0 · weight loss 1.0 · senior 1.4
Cat factors: kitten 3.0 · adult neutered 1.2 · adult intact 1.4 · active 1.6 · weight loss 0.8 · senior 1.1
How it works
This calculator estimates calorie needs for both dogs and cats using the same allometric RER formula (70 × BW0.75) used in veterinary nutrition, then applies a species- and life-stage-specific multiplier to reach the daily maintenance target. Cats generally have lower energy multipliers than dogs at equivalent life stages because of differences in metabolic rate and body composition.
The factors used are broadly consistent with National Research Council (NRC) and WSAVA guidelines but are fixed averages; individual animals may need more or fewer calories depending on body condition score, concurrent illness, or breed. Results should be treated as a starting point and adjusted based on observed weight changes over 4–6 weeks.
Worked example
Worked example
- Species = dog, weight = 10 kg, life stage = adult neutered (factor 1.6).
- RER = 70 × 10^0.75 = 70 × 5.623 ≈ 394 kcal/day.
- MER = 394 × 1.6 = 630 kcal/day.
RER 394 kcal/day, MER (daily target) 630 kcal/day
Key terms
- RER (Resting Energy Requirement)
- Calories needed to sustain basic physiological processes at rest, without accounting for activity or life stage.
- MER (Maintenance Energy Requirement)
- Total daily calorie target for a pet to maintain its current body weight given its activity level and life stage.
- Allometric scaling
- The principle that physiological rates scale as a fractional power of body mass (BW^0.75) rather than linearly, reflecting how metabolic processes change with size.
- Life stage factor
- A species-specific multiplier applied to RER; it is higher for growing animals and lower for seniors or those needing weight loss.
- Body condition score (BCS)
- A 1–9 scale used by vets to assess whether a pet is underweight, ideal, or overweight, used alongside calorie calculations to fine-tune feeding.
Frequently asked questions
- What is RER?
- Resting Energy Requirement (RER) = 70 × weight(kg)^0.75. It is the energy needed by a healthy pet at rest in a thermoneutral environment.
- What is MER?
- Maintenance Energy Requirement (MER) = RER × a life-stage factor. It accounts for normal daily activity and physiological status.