How the calories are worked out
The calculator uses the two-step method in the 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats. First it estimates the energy your pet burns at rest (RER), then multiplies by a factor for life stage and lifestyle to get the maintenance energy requirement (MER), the calories to eat in a day.
RER = 70 × (body weight in kg)0.75
MER = RER × life-stage factor
Food per day = MER ÷ calories per cup, can or gram
The factors are ranges, so the result is a range too. Start near the middle, weigh your pet every 2 to 4 weeks, and move toward the low end if it gains or the high end if it loses. AAHA says to adjust by body weight and body condition score, and that indoor or sedentary pets may need less than the table suggests.
Worked example: a 30 lb neutered dog
30 lb = 13.61 kg. 13.610.75 = 7.085, so RER = 70 × 7.085 = 496 kcal. With the neutered-adult factor of 1.4 to 1.6, the dog needs about 694 to 794 kcal a day. If the kibble has 380 kcal per cup, that is 694 ÷ 380 = 1.8 to 794 ÷ 380 = 2.1 cups a day. Setting aside 10% for treats (up to 79 kcal) brings the food down to about 1.6 to 1.9 cups.
Life-stage factors (AAHA 2021, Box 1)
| Life stage | Dog | Cat |
|---|---|---|
| Neutered or spayed adult | 1.4–1.6 | 1.2–1.4 |
| Intact adult | 1.6–1.8 | 1.4–1.6 |
| Inactive or obese-prone | 1.0–1.2 | 1.0 |
| Weight loss (on target weight) | 1.0 | 0.8 |
| Growth | 3.0 under 4 months, 2.0 from 4 months | 2.5 |
| Light work | 1.6–2.0 | – |
Source: AAHA "Energy Requirement Calculations" (Box 1). We leave out pregnancy, nursing and moderate or heavy work on purpose: AAHA's factors there run from 1.6 up to 11, depending on litter size, week of nursing and workload, which is too wide to be useful without your vet.
Turning calories into food
US pet food labels list calories under "Calorie Content". AAFCO calls for kcal per kilogram and per familiar unit such as a cup or can. Use a real measuring cup and level it off: a "cup" from a scoop or mug can be far bigger than 8 fl oz. Weighing dry food in grams (choose kcal per kg) is the most accurate.
Treats, chews and table scraps should stay under 10% of daily calories, according to WSAVA and AAHA. The calculator shows that budget in kcal.
Sources checked October 2026.
Questions people ask
How many calories does my dog need a day?
Start with the resting energy requirement, 70 × (weight in kg)^0.75, then multiply by a life-stage factor. For a typical neutered adult dog AAHA uses 1.4 to 1.6. A 30 lb (13.6 kg) neutered dog works out at about 496 kcal resting and 694 to 794 kcal a day in total.
How many calories does an indoor cat need?
For a neutered adult cat AAHA uses 1.2 to 1.4 × the resting requirement, and notes that indoor and sedentary cats may need less. A 10 lb (4.5 kg) neutered cat comes out at about 261 to 305 kcal a day. For an indoor cat, start near the low end (or use the "inactive" factor of 1.0) and adjust by weight.
Why is the bag’s feeding guide different?
Feeding guides are written for a range of dogs or cats and often assume an active, intact adult. They are a starting point, like this calculator. What matters is your pet’s body condition over the next few weeks.
Where do I find the calories in my pet’s food?
US pet food labels carry a "Calorie Content" statement, usually near the guaranteed analysis. AAFCO rules call for kcal per kilogram and per familiar unit such as a cup or can. If you can’t find it, the manufacturer can tell you.
How many treats can I give?
WSAVA and AAHA both say treats should be no more than 10% of daily calories. Tick "leave room for treats" and the calculator sets aside 10% and reduces the food amount to match. Chews, dental sticks and table scraps all count.
How should I feed a pet that needs to lose weight?
AAHA’s weight-loss factors (1.0 for dogs, 0.8 for cats) are applied to the RER for the target weight, not the current weight. Enter the target weight and choose "Weight loss". Have your vet set the target and check progress, especially for cats, which can get seriously ill if they stop eating or lose weight too fast.