Pet Calorie Calculator

Estimate a dog or cat’s daily calorie needs from body weight and life stage using the RER and MER veterinary formulas. Calculates in your browser.

Daily calorie need (MER)

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Resting need (RER)-

Show the math

Start from the resting energy requirement (the calories a pet burns at rest) then multiply by a life-stage factor to get the maintenance energy requirement:

RER = 70 × weight(kg)^0.75

MER = RER × activity factor

For weight loss or gain, the RER is worked out at the target weight, not the current one; feeding for the current weight of an overweight pet keeps it overweight.

Dog factors follow the Ohio State University Veterinary Medical Center's basic calorie calculator; cat factors follow the Merck Veterinary Manual, with mature adult and senior cats from the 2021 AAHA/AAFP Feline Life Stage Guidelines. Neutered adults sit around 1.6× (dog) or 1.2× (cat); puppies, kittens and working dogs need much more. Where the source gives a range, the result is a range.

A guide for healthy adults, your vet sets targets for growth, illness or weight change. Everything is calculated in your browser.

What this does

A pet calorie calculator estimates a dog or cat’s daily calorie needs from body weight and life stage using the RER and MER veterinary formulas.

How to use it

  1. Pick the species.
  2. Enter the body weight.
  3. Choose the life-stage factor (and the target weight for weight loss or gain).
  4. Read the daily calories.

How it works

RER is the resting energy need; MER multiplies it by a life-stage factor — neutered adults near 1.6× (dog) or 1.2× (cat), more for puppies, kittens, or working dogs. Dog factors follow the Ohio State University Veterinary Medical Center’s basic calorie calculator and cat factors the Merck Veterinary Manual; where they give a range (such as 2.0–5.0× for working dogs), the result is a range.

RER = 70 × weight(kg)^0.75; MER = RER × factor

Understanding your result

The figure is a starting estimate from body weight and life stage, not a fixed requirement. Activity, neutering, and metabolism all shift real needs, so weigh your pet regularly and adjust the amount if they gain or lose condition. Puppies, kittens, and working animals need more than neutered adults.

Example

A 10 kg neutered dog has an RER of about 394 kcal/day (70 × 10^0.75), so it needs about 630 kcal/day (394 × 1.6).

Sources & methodology

Last updated .

Frequently asked questions

What are RER and MER?

RER (resting energy requirement) is the calories burned at rest, 70 × weight(kg)^0.75. MER (maintenance energy requirement) multiplies RER by a life-stage factor for daily needs.

Which activity factor should I pick?

Neutered adults sit near 1.6× (dog) or 1.2× (cat), intact adults 1.8× or 1.4×, and inactive or obesity-prone adults less; puppies (3× to 4 months, then 2×), kittens (2.5×) and working dogs (2.0–5.0×) need substantially more.

How are calories set for weight loss?

For weight loss or gain, the resting energy is calculated at the target weight your vet recommends, not the current weight, then multiplied by the weight-change factor. Your vet may adjust the plan as your pet’s weight changes.

Is anything stored?

No. Everything is calculated locally in your browser.