Free tool · No sign-up · Vet-standard math
Pet calorie calculator — and an honest answer to “is my pet overweight?”
Get a daily calorie target for your dog or cat with the same RER/MER method veterinary teams use, plus an ideal-weight estimate and a straight verdict from a 30-second body-condition check. Everything runs on this page — nothing to install, nothing to pay.
Informational only — not veterinary advice or a diagnosis. Always consult a licensed veterinarian about your pet’s weight and diet.
Turn one number into a routine
Track meals against this target, free, in the PetLife app
The iPhone app uses this exact calorie engine every day — log food, watch weight trends, and get safety nudges when something drifts. One pet with core care logging stays free.
How the math works
No black box: this tool runs the same deterministic RER/MER calculation as the PetLife app, with every factor shown below.
Resting needs first
RER = 70 × (weight in kg)^0.75 — the calories your pet burns simply existing for a day.
Multiply by life stage
Age, spay/neuter status, and growth set the factor that turns resting needs into a daily target.
Feed for the ideal weight
Weight-loss targets use the resting needs of the ideal weight — provisionally about 10% below current when no vet goal is set.
Life-stage factors (× resting needs)
| Life stage | Dogs | Cats |
|---|---|---|
| Adult, spayed/neutered | 1.6 × RER | 1.2 × RER |
| Adult, intact | 1.8 × RER | 1.4 × RER |
| Senior | 1.4 × RER | 1.15 × RER |
| Weight loss (applied to ideal-weight RER) | 1 × RER | 0.8 × RER |
| Puppy/kitten, under 4 months | 3 × RER | 2.5 × RER |
| Juvenile, 4–12 months | 2 × RER | 2 × RER |
Breeds prone to weight gain get maintenance trimmed by 15%. Weight-loss targets always use the resting needs of the ideal weight — never the current one — which is why the tool estimates an ideal weight first.
Useful without pretending to replace your vet
This calculator is a record-keeping and educational aid. Nothing on this page is veterinary or medical advice, a diagnosis, or a treatment plan. Always consult a licensed veterinarian for questions about your pet’s weight, diet, or health — and never delay or disregard professional veterinary advice because of something you saw here. Sudden weight change, appetite loss, or a cat that stops eating is a same-day vet call, not a calculator question.
Pet calorie questions, answered
How many calories does my dog or cat need per day?
Veterinary teams start from Resting Energy Requirement (RER = 70 × body weight in kg to the 0.75 power) and multiply it by a life-stage factor. A neutered adult dog uses about 1.6 × RER and a neutered adult cat about 1.2 × RER. For example, a 66 lb (30 kg) neutered adult dog lands near 1,435 kcal per day, and a 10 lb (4.5 kg) neutered adult cat near 260 kcal per day. Your pet's real needs vary with health, body condition, and lifestyle, so treat any calculator result as a starting point to review with your vet.
How do I know if my dog or cat is overweight?
Use the rib-and-waist check: at a healthy weight you can feel the ribs easily under a thin fat layer, and see a waist tuck behind the ribs from above. If ribs are hard to find or the waist has disappeared, your pet may be carrying extra weight; if ribs, spine, or hips are clearly visible, your pet may be underweight. A veterinarian confirms this with a hands-on body condition score (BCS), which is more reliable than weight alone.
How many calories should my pet eat to lose weight?
The standard veterinary weight-loss approach feeds for the ideal weight, not the current one: about 1 × RER of ideal weight for dogs and 0.8 × RER of ideal weight for cats. When no vet-set goal exists yet, this calculator uses a provisional ideal about 10% below the current weight. Always confirm a weight-loss plan with your vet — cats in particular must never lose weight quickly, because rapid loss can trigger a dangerous liver condition.
Why does spaying or neutering change calorie needs?
Spayed and neutered pets typically burn fewer calories, so the standard factors drop — for dogs from about 1.8 × RER (intact) to 1.6 × RER, and for cats from about 1.4 × RER to 1.2 × RER. Feeding an altered pet like an intact one is a common, quiet cause of weight creep, which is why this calculator asks.
Is this calculator veterinary advice?
No. It is a free informational tool built on the widely used RER/MER framework. Nothing here is veterinary or medical advice, a diagnosis, or a treatment plan. Always consult a licensed veterinarian about your pet's weight, diet, and health, and never delay or disregard professional veterinary advice because of something you read here.