Cat Calorie Calculator
Estimate your cat's daily calorie needs from its weight and life stage using the vet RER and MER formula.
🐾 What is the Cat Calorie Calculator?
The cat calorie calculator estimates how many calories your cat needs each day based on its body weight and life stage. It uses the same two-step method that veterinary nutritionists use: first the Resting Energy Requirement, then a maintenance factor for the cat's situation. The result is a daily calorie target you can turn into an actual feeding portion.
Owners use it to answer a question every cat owner faces: how much should I feed my cat? Portion guides on food packaging are broad averages, so a calorie-based target tailored to your cat is far more reliable. It is especially valuable after neutering, when calorie needs drop and weight gain is common, and for managing an overweight cat, where feeding to a target weight under veterinary guidance is the safe approach. Kitten owners use it to make sure a growing cat gets enough energy.
The method matters. The Resting Energy Requirement, RER = 70 times body weight in kilograms raised to the power 0.75, captures the energy a cat uses at rest. Because the exponent is 0.75 rather than 1, calorie needs do not scale in a straight line with weight, which is why an accurate weight is important. Multiplying the RER by a life-stage factor, such as 1.2 for a neutered adult or 2.0 for a growing kitten, gives the Maintenance Energy Requirement, the everyday calorie target.
This tool is useful because it replaces guesswork with a vet-informed number, converts pounds to kilograms for you, and shows the working so you understand where the figure comes from and how to adjust it as your cat's weight and condition change.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 - Neutered adult, 4.5 kg
Example 2 - Growing kitten, 3 kg (4 to 12 months)
Example 3 - Overweight cat on a diet, 6 kg
❓ Frequently Asked Questions
🔗 Related Calculators
How many calories does a cat need per day?
Most neutered adult cats need about 200 to 280 calories a day. The exact number comes from the Resting Energy Requirement (70 x body weight in kg to the power 0.75) multiplied by a life-stage factor. A 4.5 kg neutered adult cat needs about 260 calories a day.
How is a cat's calorie requirement calculated?
Start with the Resting Energy Requirement, RER = 70 x weight in kg to the power 0.75. Then multiply by a maintenance factor for the cat's life stage and goal: about 1.2 for a neutered adult, 1.4 for intact, 2.0 to 2.5 for kittens, 1.1 for seniors, and 0.8 for weight loss. The result is the daily calorie target.
How much should I feed my cat?
Match the daily calorie target to your cat food's energy density. If the food provides 400 kcal per cup and your cat needs 260 kcal a day, that is about two-thirds of a cup daily, split across meals. Always use the kcal figure on the label rather than guessing by volume.
Why do neutered cats need fewer calories?
Neutering lowers a cat's metabolic rate and often reduces activity, so energy needs drop by roughly 15 to 30 percent. This calculator uses a factor of 1.2 for neutered adults versus 1.4 for intact adults. Not reducing portions after neutering is a common cause of weight gain.
How many calories does a kitten need?
Kittens need far more energy per kilogram than adults because they are growing. This calculator uses a factor of 2.5 for kittens under 4 months and 2.0 for kittens aged 4 to 12 months. A 3 kg kitten in the 4 to 12 month range needs roughly 320 calories a day.
How do I help my cat lose weight safely?
Use the weight-loss setting, which applies a factor of 0.8 to the resting requirement, and feed to your cat's target weight rather than current weight. Aim for gradual loss of about 0.5 to 1 percent of body weight per week, and always plan a weight-loss diet with your veterinarian, as rapid loss can cause serious liver problems in cats.
Does the calorie estimate change with weight in pounds?
The formula uses kilograms, so this calculator converts pounds to kilograms first (1 lb = 0.4536 kg) before applying RER = 70 x kg to the power 0.75. You can enter weight in either unit and the result is the same daily calorie figure.
How accurate is the cat calorie calculator?
It gives a solid starting estimate, but individual cats vary by up to 20 percent based on activity, metabolism, and health. Use it as a baseline, then monitor your cat's weight and body condition over a few weeks and adjust portions. Your veterinarian can fine-tune the target for medical conditions.