How we calculate calories and ideal weight
PawAI uses the same energy math veterinary teams use — no proprietary black box. Resting energy is RER = 70 × (body weight in kg)^0.75; daily maintenance calories are that RER multiplied by a life-stage factor (MER). Weight loss follows the AAHA rule of feeding 0.80 × RER of the target weight. This page is free to cite with attribution to PawAI.
Resting energy (RER)
RER (kcal/day) = 70 × (BWkg)0.75. We use the exponential form for all weights and both species; the linear 30·kg + 70 shortcut overestimates outside 2–25 kg, so we never use it.
Maintenance factors (MER = factor × RER)
| Life stage | Dog (× RER) | Cat (× RER) |
|---|---|---|
| Intact adult | 1.8 | 1.4 |
| Spayed/neutered adult | 1.6 | 1.2 |
| Inactive / obesity-prone | 1.3 | 1 |
| Senior | 1.4 | 1.3 |
| Weight loss (maintenance factor) | 1 | 0.9 |
Mid-points are used where a guideline gives a range. Growing puppies use 2–3 × RER (kittens 2.5×).
Weight loss
Daily budget = 0.8 × RER computed from the ideal/target weight, not the current weight (AAHA 2014). For safety the fraction is floored at 0.8 for cats (hepatic-lipidosis risk) and 0.6 for dogs, and loss is targeted at 1–2%/week (dogs) or 0.5–2%/week (cats).
Body condition over the scale number
The ideal weight itself is estimated from body condition score (BCS 1–9), because breed weight ranges are wide and the number on the scale matters less than the condition of the body. Check your dog's body condition from a photo.
Sources
- AAHA 2014 Weight Management Guidelines for Dogs and Cats
- WSAVA Global Nutrition Guidelines
- Pet Nutrition Alliance — Calorie Calculator & RER/MER tables
- Association for Pet Obesity Prevention (APOP)
Last reviewed 2026-07-22.