How the daily calorie number is worked out
Vets start from resting energy: the calories a dog burns lying still in a comfortable room. The formula in the AAHA weight management guidelines is:
Resting energy (kcal a day) = 70 × weight in kg0.75
The power of 0.75 is there because small dogs burn more energy per kilogram than big ones. A 5 kg dog is a quarter of the weight of a 20 kg dog, but needs about 35% of its calories, not 25%.
A real day includes walks, play and digestion, so resting energy is multiplied by a life-stage factor. The calculator uses one number from inside each range the AAHA 2021 Nutrition and Weight Management Guidelines give:
| Your dog | Factor used | AAHA 2021 range |
|---|---|---|
| Neutered or spayed, normal activity | × 1.5 | 1.4 to 1.6 |
| Not neutered, normal activity | × 1.7 | 1.6 to 1.8 |
| Low activity, or a body score of 6 or more | × 1.1 | 1.0 to 1.2 |
| High activity (runs daily, working dog) | × 1.8 | 1.6 to 2.0 |
When two rows apply, the lower one wins: a dog over ideal weight or with low activity gets 1.1 even if it is not neutered. The ranges come from AAHA 2021, Box 1; the high-activity range shown is the one for light work.
A worked example
A neutered 20 kg dog with normal activity and an ideal body: 70 × 200.75 = 662 kcal of resting energy, × 1.5 = 993 kcal a day. Treats should stay under 99 kcal of that.
The same maths for a 30 kg dog that is not neutered, walks little and scores 7 on the body scale: a 7 is about 20% over ideal, so the ideal weight is 30 ÷ 1.2 = 25 kg. Resting energy for 25 kg is 783 kcal, × 1.1 = 861 kcal a day.
Daily calories by weight
For an adult dog with normal activity and an ideal body. Most pet dogs are neutered; use the second column if yours is not.
| Weight | Neutered | Not neutered |
|---|---|---|
| 5 kg (11 lb) | 351 kcal | 398 kcal |
| 10 kg (22 lb) | 590 kcal | 669 kcal |
| 15 kg (33 lb) | 800 kcal | 907 kcal |
| 20 kg (44 lb) | 993 kcal | 1,125 kcal |
| 30 kg (66 lb) | 1,346 kcal | 1,525 kcal |
| 40 kg (88 lb) | 1,670 kcal | 1,893 kcal |
| 50 kg (110 lb) | 1,974 kcal | 2,238 kcal |
A dog that is overweight or walks little gets the lower factor (× 1.1), and a very active dog a higher one (× 1.8), so its number will differ. Puppies are not in the table. The calculator above works it out for your dog, and turns it into grams of food.
Why it’s an estimate
Dogs of the same weight differ. The WSAVA nutritional assessment guidelines say energy needs can vary by about 30% either way, and a 2014 review of every published study on adult dogs found individuals far apart. So treat the number as a starting point: weigh your dog once a month on the same scale, and if the weight drifts, adjust the amount a little and check again.
Treats count too
Treats, chews and table scraps should stay at or under 10% of the day’s calories, so the main food still supplies the nutrients a dog needs (AAHA 2014 and 2021). Treat calories add up quickly for small dogs, so check the packet.
What if my dog is overweight?
Vets judge weight with the body condition score, a 1 to 9 scale you check with your hands: 4 and 5 are ideal, and each point above 5 means about 10% over ideal weight. Feeding for the current weight of an overweight dog keeps it there, so the calculator (and the app) uses the estimated ideal weight and the lower factor instead.
Before a weight-loss plan, see your vet: extra weight can have a medical cause that feeding cannot fix. A safe pace is 1 to 2% of body weight a week (AAHA 2014), and the calculator never goes below 70% of resting energy.
Puppies and senior dogs
Puppies under 12 months need two to three times their resting energy, and the right amount depends on age and expected adult size. That feeding is vet-guided, so the calculator gives no number for puppies. Large and giant breeds can keep growing until 15 or 16 months.
Senior dogs may need a little less, but the guidelines say the findings are not consistent and no study gives a factor. The calculator uses the adult number; the monthly weigh-in tells you if it needs to change.
How to turn calories into grams
Find the energy on the bag. Some labels give kcal per 100 g; others give kcal per kg (divide it by 10) or per cup. Then:
Grams a day = daily kcal ÷ kcal per 100 g × 100
For example, 993 kcal of a dry food with 350 kcal per 100 g is 993 ÷ 350 × 100 = about 284 g a day. Weigh it on a kitchen scale rather than using a scoop.
Sources
- AAHA Weight Management Guidelines for Dogs and Cats (2014). J Am Anim Hosp Assoc 50:1–11. doi:10.5326/JAAHA-MS-6331
- AAHA Nutrition and Weight Management Guidelines for Dogs and Cats (2021). J Am Anim Hosp Assoc 57, Box 1.
- WSAVA Nutritional Assessment Guidelines (2011). J Small Anim Pract 52:385–396.
- Bermingham E.N. et al. Energy Requirements of Adult Dogs: A Meta-Analysis. PLoS ONE (2014). doi:10.1371/journal.pone.0109681
- WSAVA Global Nutrition Committee, Body Condition Score chart for dogs (9-point scale). wsava.org
- Association for Pet Obesity Prevention, Step Weight Loss Calculator (the 70% floor). petobesityprevention.org
Last reviewed 26 September 2026. Every figure here was checked against the guideline documents listed above.
This calculator gives an estimate for healthy adult dogs. It is not veterinary advice; if your dog is ill, pregnant, nursing or on a special diet, ask your vet.
