1. Resting energy
Resting energy requirement (RER) is the energy a pet uses at rest: RER = 70 × body weight in kg0.75. A 20 kg dog needs about 662 kcal a day at rest.
2. Life stage and lifestyle
We multiply RER by the factor for your pet, from the 2021 AAHA Nutrition and Weight Management Guidelines and the Merck Veterinary Manual. We use the typical value and show the full range.
| Pet | Dog | Cat |
|---|---|---|
| Spayed or neutered adult | 1.6 (1.4–1.6) | 1.2 (1.2–1.4) |
| Intact adult | 1.8 (1.6–1.8) | 1.4 (1.4–1.6) |
| Inactive or gains weight easily | 1.2 (1.0–1.2) | 1.0 |
| Very active dog | 2.0 (1.6–2.0) | – |
| Working dog | 3.0 (2.0–5.0) | – |
| Weight loss, at target weight | 1.0 | 0.8 |
| Puppy under 4 months | 3.0 | – |
| Puppy 4 months and older | 2.0 | – |
| Kitten | – | 2.5 |
3. The food’s own calories
Every dog and cat food sold in the US prints its calorie content as kcal per kg and kcal per cup or can. UK labels give kcal per 100 g. We divide your pet’s daily energy by that number. If you give treats, we keep 10% of the calories for them, as WSAVA advises.
Why the number is a starting point
Two pets of the same weight can need noticeably more or less than the formula says. Weigh your pet every two weeks. If they gain, cut the amount by about 10%; if they lose, add 10%. A vet should plan weight loss and the diet of a pet that is pregnant, nursing, ill or on a prescription food.
Where the calorie data comes from
We read each product’s calorie content from the manufacturer’s page, or from a large retailer that shows the label when the manufacturer does not. Each food page links to its source and the date we checked it. If your bag shows a different number, use your bag’s number with the “type the calories from the bag” option.
Sources
- AAHA. 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats.
- Merck Veterinary Manual. Daily maintenance energy requirements for dogs and cats.
- WSAVA. Feeding treats to your dog and feeding treats to your cat.