Dog and Cat Calorie Calculator: Daily Needs and Weight Loss

Daily calorie calculator

Animal

Current weight

Life stage and activity

Goal

Calories in the food (optional, see the label)

Estimated daily calories:-kcal/day

Resting energy (RER)-

Factor-

Food per day-

Estimate only: real needs vary a lot from one animal to another. Adjust the amount with regular weigh-ins and the body condition score, with your vet. For a sick, pregnant or nursing animal, ask your vet.

How to use this calculator

1

Animal and weight

Choose dog or cat and enter the weight in kg or lb. Weigh your animal on a scale if you can.

2

Life stage

Neutered or intact adult, inactive, puppy or kitten. The factor changes with each profile.

3

Goal

For weight loss, enter the ideal weight that your vet gave you. The calculation then uses that weight.

4

Food

Add the calories printed on the food label to get a daily amount in cups, grams or cans.

The formula: RER × factor

Resting energy requirement:

RER (kcal/day) = 70 × (weight in kg)^0.75

Daily energy requirement:

Calories per day = RER × life-stage factor

This is the method of the 2021 AAHA Nutrition and Weight Management Guidelines. AAHA gives an example: a neutered 10 lb dog has an RER of 216 kcal, and with a factor of 1.4 its daily needs are about 302 kcal. Some sources use a linear formula (30 × kg + 70), but it is only valid between about 2 and 45 kg. This calculator always uses the exponent formula.

Factors by life stage

Profile	Dog: factor used (AAHA range)	Cat: factor used (AAHA range)
Neutered adult	1.6 (1.4 to 1.6)	1.2 (1.2 to 1.4)
Intact adult	1.8 (1.6 to 1.8)	1.4 (1.4 to 1.6)
Inactive or prone to weight gain	1.2 (1.0 to 1.2)	1.0
Weight loss (on ideal weight)	1.0	0.8
Growth	3.0 under 4 months, 2.0 from 4 months	2.5

The single values match the Merck Veterinary Manual table. The ranges come from AAHA 2021, which tells vets to base the calculation on the ideal weight. The WSAVA calorie sheets (2020) give ranges in kcal per day by weight, which you can use as a cross-check.

Weight loss: go slowly

Dogs: about 1 to 2 % of body weight per week.
Cats: 0.5 to 2 % per week according to AAHA. The iCatCare 2025 guidelines for overweight diabetic cats recommend a maximum of about 0.5 to 1 % per week. The calculator uses the more careful value.
Never starve a cat. An overweight cat that stops eating can develop hepatic lipidosis (fatty liver), a disease that can kill.
If the plan gives less than 60 % of the resting energy at the current weight, AAHA advises a veterinary nutritionist.
Weigh your animal regularly and adjust the amount with your vet.

Why it matters

In the 2022 survey of the Association for Pet Obesity Prevention (APOP), 59 % of dogs and 61 % of cats were overweight or obese. Excess weight increases the risk of joint disease and, in cats, of diabetes. In an overweight diabetic cat, weight loss is part of the treatment plan. If your animal receives insulin, check the syringe with our U-40 / U-100 insulin syringe converter.

Sources

Cline MG, Burns KM, Coe JB et al.. 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats. J Am Anim Hosp Assoc 57(4):153-178, 2021.
Brooks D, Churchill J, Fein K et al.. 2014 AAHA weight management guidelines for dogs and cats. J Am Anim Hosp Assoc 50(1):1-11, 2014.
Freeman L, Becvarova I, Cave N et al.. WSAVA Nutritional Assessment Guidelines. J Small Anim Pract 52(7):385-396, 2011.
WSAVA Global Nutrition Committee. Calorie needs for healthy adult dogs. WSAVA, 2020.
National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, 2006.
Merck Veterinary Manual. Daily maintenance energy requirements for dogs and cats. Merck Veterinary Manual, 2026.
Taylor S et al.. iCatCare 2025 consensus guidelines on the diagnosis and management of diabetes mellitus in cats. J Feline Med Surg 27(11), 2025.
Webb CB. Hepatic lipidosis: clinical review drawn from collective effort. J Feline Med Surg 20(3):217-227, 2018.
Association for Pet Obesity Prevention. 2022 State of Pet Obesity Report. APOP, 2022.

Frequently Asked Questions

How many calories does my dog need per day?

Calculate the resting energy (RER = 70 × weight in kg^0.75), then multiply by the factor for the life stage: about 1.6 for a neutered adult dog and 1.8 for an intact adult. For a 20 kg neutered dog, that is about 1,060 kcal per day. It is an estimate: adjust it with weigh-ins.

How many calories does my cat need per day?

Use the same RER, then a factor of about 1.2 for a neutered indoor cat and 1.4 for an intact cat. For a 4 kg neutered cat, that is about 240 kcal per day.

How do I calculate calories for weight loss?

AAHA bases the calculation on the ideal weight, not the current weight: RER at ideal weight × 1.0 for a dog and × 0.8 for a cat. Your vet sets the ideal weight with the body condition score.

How fast can my dog or cat lose weight?

About 1 to 2 % of body weight per week for a dog. For a cat, go slower: 0.5 to 1 % per week is a careful target. A cat must never fast, because of the risk of hepatic lipidosis.

Why is the result different from the amount on the food bag?

Feeding guides on bags are averages for active, intact animals. Most pets are neutered and less active. Use the label only for the calories per cup or per 100 g, and adjust with your vet.

Does the calculator work for puppies and kittens?

It gives the growth factors of AAHA (3.0 for a puppy under 4 months, 2.0 after, 2.5 for a kitten) for maintenance only. It does not calculate weight loss for a growing animal: ask your vet.

Is the calculator a substitute for a vet visit?

No. Needs vary a lot between animals, and diseases (thyroid, kidneys, diabetes) change them. Use the result as a starting point to discuss with your vet.