CalcelateSearch

Cat calorie calculator

Work out how many calories your cat needs per day from weight and life stage using the veterinary RER × factor method, then convert to cups of dry food and cans of wet food from your labels.

Units
kg

Use the ideal weight if the cat is overweight; the current weight overfeeds.

kcal
kcal
%

Daily requirement

show

In cups and cans

show

Same cat, other life stages

show
StageFactorCalories

Feeding guides on cat food bags are generous by design, and most indoor cats end up overweight. Vets instead calculate an individual requirement from body weight and life stage, then adjust from there. This calculator uses the same method and converts the result into portions of your actual food.

How it is calculated

  1. Resting energy requirement (RER) = 70 × body weight in kg0.75. This is the energy a cat uses at rest in a comfortable room.
  2. Daily requirement (MER) = RER × a factor for life stage: 1.2 for a typical neutered adult, 1.4 intact, 1.0 for inactive cats, 0.8 for weight loss, 2–2.5 for kittens, up to 3 for a nursing queen.
  3. Portions = calories ÷ the calorie content on the label. Dry food is usually 350–450 kcal per cup; a 5.5 oz (156 g) can of wet food 150–200 kcal.

Example

A 4.5 kg neutered indoor cat: RER = 70 × 4.50.75 ≈ 216 kcal; × 1.2 = about 260 kcal a day. Split half and half between a 400 kcal/cup dry food and 180 kcal cans: about a third of a cup of dry food plus three-quarters of a can. Many bags would suggest nearly twice that.

Adjusting

The formula gives a starting point, not a prescription; individual cats vary by 20% or more. Weigh the cat every two weeks and feel the ribs: they should be easy to feel under a thin layer of fat, and the cat should have a visible waist from above. If weight creeps up, cut 10%; if ribs become prominent, add 10%. For overweight cats, calculate at the ideal weight and use the weight-loss factor, but never crash-diet a cat: losing more than 1–2% of body weight a week can trigger hepatic lipidosis.

Treats and extras

Keep treats under 10% of daily calories, about 25 kcal for the cat above. A single Temptations-type treat is about 2 kcal; a tablespoon of tuna about 15.

Frequently asked questions

How many calories should a cat eat per day?

Roughly 20 kcal per pound of ideal body weight for an average indoor adult, or about 200–300 kcal for a 4–5 kg cat. Kittens, pregnant and nursing cats need much more. Enter the weight and stage above for an exact figure.

How much dry food should I feed my cat?

Divide the daily calories by the kcal per cup on the bag. For a 260 kcal cat on 400 kcal/cup food, about two-thirds of a cup a day if fed only dry. Measure with a proper measuring cup or a kitchen scale.

Is wet or dry food better?

Wet food has far more water, which helps urinary health, and is harder to overfeed; dry food is convenient and cheaper. Many vets suggest a mix. Calories are what matter for weight.

How do I know if my cat is overweight?

You should feel the ribs easily with light pressure and see a waist behind the ribs from above. If you have to press to find ribs, the cat is overweight. Vets use a 9-point body condition score; 5 is ideal.

How fast can a cat safely lose weight?

No more than 1–2% of body weight per week, about 50–100 g for a 5 kg cat. Faster loss risks fatty liver disease. Weigh monthly and adjust in small steps with your vet.

Sources

  1. WSAVA Global Nutrition Committee: Nutritional Assessment Guidelines
  2. AAHA Nutritional Assessment Guidelines for Dogs and Cats
  3. Pet Nutrition Alliance: Calorie calculator (RER formula)

By Calcelate Team. Formula from the sources above.

  1. 2026-09-14 · Formula and texts checked