Pet health

How to Calculate Your Cats Daily Calorie Intake

How to Calculate Your Cats Daily Calorie Intake

Just like with people, a cat's calorie needs depend on several factors. Calories, the technical term for energy from food, are required for essential processes such as digestion, respiration, nervous and circulatory system control, and other normal bodily functions. In addition to the body's basic needs for everyday life, a cat's daily intake is determined by their age, sex, activity level, and body condition. For example:

  • Young cats, those who have not been spayed or neutered, active cats, sick cats, and underweight cats need more calories.
  • Older cats, spayed or neutered cats, inactive cats, and overweight or immobile cats need fewer calories.

How to Calculate How Much Your Cat Can Eat Per Day

Feeding too little food can deprive your cat of necessary energy, and feeding too much can result in obesity. To determine how much food your cat should eat per day, follow these steps.

  1. Use a calorie calculator to calculate your cats Resting Energy Requirements (RER).
  2. Choose a factor based on your cat's energy needs and multiply it by the RER. This gives you the number of calories your cat should eat in a day.
  3. Determine how many calories are in your cat's food. You can find this on the package of some foods or on line. Once you know the calories in what you are feeding, you can figure out how much he or she needs.
  4. Figure out the amounts to feed. If you feed your cat two meals a day, subtract the calorie count of any treats and divide the remainder by 2 to determine how many calories your cat should get for each meal. Use the calorie count for your cat's specific food to measure properly. For example, if your cat can eat 200 calories a day and you are feeding a food that is 100 calories per cup, your cat can get 2 cups per day.

Here's another example: if the cat mentioned above can eat 200 calories per day but also eats 5 treats per day (at 10 calories each), you would determine their intake as follows: 200 calories - 50 calories of treats = 150 calories left for food. If the food is 100 calories per cup, your cat can get a total of 1 ½ cups per day.

Every food is slightly different in regard to the amount of calories it contains per cup. Take human food, for example: 1 cup of cooked green beans has about 44 calories, but a cup of macaroni salad is 360 calories. Cat food is the same way in that some formulas are more calorie dense (so you need to feed less) than others.

Cat Calorie Calculator

The basic core calorie requirements for cats are determined by Resting Energy Requirements or RER, which can be calculated by raising the animal's body weight in kilograms to the ¾ power and multiplying that total by 70.

For example:

  • A 6 lb. cat (around 2.7 kg) adult neutered cat of healthy weight needs an
    RER of 70(2.7kg)(¾) ̳ 400 calories/day.

The calculator that many veterinarians use to calculate RER calorie requirements is provided by Hill's Pet Nutrition and is as follows:

Body weight (lbs)Body weight (kg) RER ( calories per day)
 1 0.5 39
 2 0.9 65
 3 1.4 88
 4 1.8 110
 5 2.3 130
 6 2.7 149
 7 3.2 167
 8 3.6 184
 9 4.1 291
 10 4.5 218
 11 5 234
 12 5 250
 13 5.9 265
 14 6.4 280
 15 6.8 295
 16 7.3 310
 17 7.7 324
 18 8.2 339
 19 8.6 353
 20 9.1 366
 25 11.4 433

NOTE: The “calorie” we refer to in food is actually kilocalorie.

An RER fulfills the cat's basic needs but does not account for things like activity levels or other factors. To do so, the RER number is multiplied by factors to estimate the pet's total daily energy needs. Some pets need less than the RER and some need nearly double the RER.

Life stages factors to estimate
daily energy needs for cats
Neutered adult cat = 1.2 x RER
Intact adult cat = 1.4 x RER
Inactive/obese prone cat = 1 x RER
Weight loss for cat = 0.8 x RER for ideal weight
Weight gain for cat = 1.8 x RER for ideal weight
Kitten 0-4 months = 2.5 x RER
Kitten 4 months to 1 year = 2 x RER

*From the Ohio State University College of Veterinary Medicine ( //

I hope this helps you calculate the calorie needs of your cat. Remember to consult your vet with any questions or concerns regarding your cat's dietary needs.