What Is the Cat Calorie Calculator?
This tool estimates how many calories (kilocalories) your cat needs each day to maintain a healthy weight. It uses the widely accepted veterinary formula based on the cat's Resting Energy Requirement (RER) scaled by a life-stage or activity factor. The RER reflects the energy a cat burns at complete rest, and the factor adjusts for whether the cat is dieting, neutered, active, pregnant, lactating, or still growing.
How to Use It
Enter your cat's weight in kilograms, then choose the factor that best matches its situation. Press calculate to see the estimated daily calorie target plus the underlying RER value. Use this as a starting point and adjust based on your cat's body condition and your veterinarian's advice.
The Formula Explained
The calculation is two steps. First, $$\text{RER} = 70 \times \text{weight}_{kg}^{0.75}$$ The 0.75 exponent (metabolic body weight) reflects that smaller animals burn more calories per kilogram than larger ones. Second, the daily energy requirement \(= \text{RER} \times \text{factor}\), where typical factors range from 0.8 (weight loss) to 2.5 (kitten growth).
Worked Example
A neutered adult cat weighing 4 kg with a factor of 1.0: $$\text{RER} = 70 \times 4^{0.75} = 70 \times 2.8284 = 197.99 \text{ kcal}$$ Daily need \(= 197.99 \times 1.0 \approx\) 198 kcal per day.
FAQ
Is this a substitute for a vet? No. It provides a science-based estimate, but your veterinarian should confirm targets, especially for weight loss or medical conditions.
Why is the exponent 0.75? Energy use does not scale linearly with body mass; metabolic body weight (\(\text{kg}^{0.75}\)) gives a far more accurate baseline across body sizes.
How do I convert calories to food amount? Check the kcal-per-cup or kcal-per-can value on your cat food label, then divide the daily calorie target by that number.
