Cat Calorie Calculator

How the calculator works

It uses the same starting method as most veterinary nutrition references, with factors chosen for cats. Cats are usually less active than dogs of a similar weight, so the dog multipliers would overestimate what most cats need.

1. Resting energy requirement (RER): 70 × body weight in kilograms to the power of 0.75. This is the energy a cat uses at rest in a comfortable environment.
2. Life-stage factor: the RER is multiplied by a factor for age, neutering and activity. A neutered adult with normal activity uses 1.2, an intact adult 1.4, an inactive adult or one that gains weight easily 1.0, and a growing kitten 2.5.
3. Treats and extras: about 10 percent of the day's calories is set aside for treats, dental chews and anything else the cat eats outside its main food.
4. Portion (optional): the rest is divided by the food's energy content. For a food labeled in kcal per kilogram, the result is grams a day. For a food labeled per pouch, can or cup, it is the number of portions a day, rounded to the nearest quarter.

A worked example

A healthy, neutered indoor cat weighs 4 kg and is at a good body condition.

• RER: 70 × 4^0.75 is about 198 kcal a day.
• Daily estimate: 198 × 1.2 is about 238 kcal a day.
• Treat allowance: about 24 kcal, which leaves about 214 kcal for the main food.
• With a dry food that provides 3,600 kcal per kg, that is about 59 g a day. With pouches of 70 kcal each, it is about 3 pouches a day.

These food figures are for illustration only: use the numbers on the label of the food the cat actually eats.

Many owners feed a mix of wet and dry food. Work out the wet portion first, subtract its calories from the main food figure, and fill the rest with dry food. Weigh dry food on kitchen scales rather than using a cup. With portions this small, a slightly heaped cup adds a real share of the day's calories.

Treat the result as a starting point

Two cats of the same weight can need quite different amounts, and published factors vary a little between sources. What matters is what happens over the next few weeks:

• Feed the suggested amount and weigh the cat on the same scales every few weeks.
• Check body condition: you should feel the ribs easily under a slight covering of fat and see a gentle waist from above. The body condition score guide walks through it.
• If a healthy adult cat slowly gains or loses weight, adjust the portion in small steps and check again.

In a home with several cats, a cat that seems to overeat on paper may simply be eating another cat's food. Separate feeding stations help, and so do puzzle feeders, which also slow eating and add activity for indoor cats.

Why there is no number for weight loss

A cat that stops eating, or loses weight too quickly, is at risk of hepatic lipidosis (fatty liver disease), a serious condition that needs urgent veterinary care. That is why this calculator does not give a weight-loss figure. Never fast a cat, skip meals or cut its food sharply. A vet examines the cat, rules out medical causes, sets the target weight and a safe rate of loss, and checks progress with regular weigh-ins.

When not to use it

The calculator is for healthy cats. Talk to a vet instead of relying on a formula if the cat:

• is pregnant or nursing;
• has a medical condition or eats a prescription diet;
• needs to lose or gain weight;
• has lost weight without a planned change, eats less than usual or refuses food.

A cat that eats less for more than a day or so needs a vet, not a new food. For kittens, the kitten factor is a rough starting point: weigh them often, because they grow quickly, and follow the vet's advice.

Learn more

The full method, with the common mistakes and how to turn a number into a plan an owner will follow, is in our guide to how to calculate a cat's calorie needs. To find the calorie content on a label and compare foods fairly, see how to read a pet food label. For growing animals, read feeding puppies and kittens, and for dogs, use the dog calorie calculator.