Determining the correct caloric intake for your feline friend is crucial for preventing obesity, which is the leading health issue in domestic cats. This calculator uses the Resting Energy Requirement (RER) formula, which is the energy used by a mammal at rest in a thermoneutral environment.
The Formula
The calculation is performed in two steps:
RER: 70 × (Body Weight in kg)0.75
MER: RER × Activity Multiplier
Weight Management
If your cat is overweight, use their "ideal weight" in the calculator rather than their current weight, or select the "Weight Loss Regime" multiplier to safely reduce intake.
Typical Calorie Examples
Cat Weight
Neutered Adult
Inactive Adult
8 lbs (3.6 kg)
218 kcal
182 kcal
10 lbs (4.5 kg)
261 kcal
218 kcal
12 lbs (5.4 kg)
301 kcal
251 kcal
Factors Influencing Caloric Needs
While this calculator provides a scientifically-backed estimate, several factors can change your cat's specific needs:
Metabolism: Just like humans, some cats naturally burn calories faster than others.
Breed: Larger breeds like Maine Coons require significantly more energy than a Singapura.
Environment: Cats in colder climates may burn more energy to maintain body temperature.
Health Status: Cats recovering from surgery or fighting chronic illness may have increased or decreased requirements.
Note: Always consult with your veterinarian before starting a strict weight loss diet to ensure your cat receives proper nutrition and avoids hepatic lipidosis.
var currentUnit = 'lbs';
function setUnit(unit) {
currentUnit = unit;
var btnLbs = document.getElementById('btnLbs');
var btnKgs = document.getElementById('btnKgs');
if (unit === 'lbs') {
btnLbs.className = 'active';
btnKgs.className = ";
} else {
btnLbs.className = ";
btnKgs.className = 'active';
}
}
function calculateCatCalories() {
var weightInput = document.getElementById('catWeight').value;
var multiplier = document.getElementById('catStatus').value;
var resultArea = document.getElementById('resultArea');
var kcalResult = document.getElementById('kcalResult');
var rerNote = document.getElementById('rerNote');
if (!weightInput || weightInput <= 0) {
alert('Please enter a valid weight.');
return;
}
var weightInKg = parseFloat(weightInput);
if (currentUnit === 'lbs') {
weightInKg = weightInKg / 2.20462;
}
// RER Formula: 70 * (weight in kg)^0.75
var rer = 70 * Math.pow(weightInKg, 0.75);
// Maintenance Energy Requirement (MER)
var mer = rer * parseFloat(multiplier);
var finalKcal = Math.round(mer);
var rerVal = Math.round(rer);
kcalResult.innerHTML = finalKcal;
rerNote.innerHTML = 'Based on a Resting Energy Requirement (RER) of ' + rerVal + ' kcal/day.';
resultArea.style.display = 'block';
// Scroll to result smoothly
resultArea.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}