Estimate your cat’s daily calories. This free cat calorie calculator uses the vet RER/MER formula with weight and life-stage/activity to give a daily feeding target and per-meal amount.
Enter your cat’s weight and pick the option that fits. The estimate uses the resting energy requirement (RER) scaled by a life-stage and activity factor.
Formula: RER = 70 x (weight in kg)^0.75, then daily calories (MER) = RER x activity factor. A 4.5 kg neutered adult cat needs roughly 220–260 kcal a day. Never crash-diet a cat — rapid weight loss can cause serious liver disease.
What This Cat Calorie Calculator Does
A cat calorie calculator estimates daily energy needs using the standard veterinary RER and MER formulas, adjusted for whether your cat is neutered, indoor, growing or losing weight.
How Cat Calories Are Calculated
RER = 70 x (weight in kg)^0.75daily calories (MER) = RER x activity factor
So a 4.5 kg neutered adult cat needs roughly 220–260 calories a day; indoor cats are often a little lower.
Activity Factors for Cats
| Cat | Factor (x RER) |
|---|---|
| Weight loss | 0.8 |
| Indoor / inactive | 1.0 |
| Neutered adult | 1.2 |
| Intact adult | 1.4 |
| Kitten (growing) | 2.5 |
Turning Calories Into Food
Check the kcal per can or per cup on your cat food, then divide the daily target by that to find how much to feed. Many cats do well with measured meals rather than free-feeding.
A Caution on Cat Weight Loss
Never crash-diet a cat. Rapid weight loss can trigger hepatic lipidosis (fatty liver disease), which is serious. Any weight-loss plan should be gradual and supervised by your vet.
How to Use the Cat Calorie Calculator
- Enter your cat’s weight in kg or lb.
- Choose life stage / activity.
- Read the daily calories and per-meal amount.
Have a dog too? See our Dog Calorie Calculator.
Turning the Cat Calorie Calculator Result into Real Portions
A cat calorie calculator gives a daily energy target in kcal, but you feed grams or pouches, so the conversion step is where many portions go wrong.
- Use the kcal figure on your specific food’s label, usually given per kg, per cup or per can.
- Count treats. Vets often suggest keeping them to about 10% of daily calories, with meals reduced to match.
- If you mix wet and dry food, split the cat calorie calculator target between them rather than feeding a full portion of each.
Weigh your cat every few weeks and track body condition. The cat calorie calculator is a starting point: neutered, indoor and older cats often need less.
Never put a cat on a crash diet. Rapid weight loss in overweight cats can trigger hepatic lipidosis, a serious liver disease, so ask your vet before cutting below the cat calorie calculator estimate. The cat food article on Wikipedia explains nutrients such as taurine that matter as much as the number from a cat calorie calculator.