About the Cat Food Calculator
This cat food calculator answers “how much should I feed my cat?” in the units on your food packaging. Enter your cat’s weight and life stage, the calories per cup of your dry food and per can of your wet food, and the share of calories you want from wet food. It returns daily calories, cups of kibble, cans of wet food and the amount per meal.
It suits new cat owners, anyone switching foods or mixing wet and dry, and owners trying to help a cat lose or gain weight. Feeding guides printed on bags are often generous, and indoor neutered cats easily gain weight, so a calorie-based portion is a better starting point.
The math uses the veterinary resting energy requirement (RER = 70 × body weight in kg^0.75) multiplied by a life-stage factor. Every cat is different: weigh your cat every 2–4 weeks and adjust portions by about 10% if its weight or body condition moves the wrong way. For weight loss, enter the target weight, not the current one, and involve your vet.
With the default inputs, the daily calories is 261 kcal. Change any value above to recalculate instantly.
How to use the cat food calculator
- 1Enter your cat’s weight (or target weight for loss/gain).
- 2Choose the life stage or goal that fits your cat.
- 3Set how much of the diet should come from wet food.
- 4Enter kcal per cup and kcal per can from the food labels.
- 5Split the daily amount across the number of meals you feed.
Formula and method
The resting energy requirement (RER) is the energy a cat uses at rest in a comfortable environment, calculated from body weight in kilograms raised to the 0.75 power. It is multiplied by a life-stage factor to get the maintenance energy requirement: about 1.2 for a neutered adult, 1.4 for an intact adult, 1.0 for inactive cats, 0.8 for weight loss (at target weight), 2.5 for kittens and 3.0 for young kittens.
Daily calories are then split between wet and dry food by the percentage you choose and converted to cups and cans using the calorie content printed on each package.
- W
- Body weight in kilograms (target weight for loss/gain)
- RER
- Resting energy requirement, kcal/day
- factor
- Life-stage multiplier (0.8–3.0)
Worked examples
10 lb neutered cat, half wet and half dry
A 10 lb cat weighs 4.54 kg, so RER = 70 × 4.54^0.75 ≈ 218 kcal. A neutered adult needs about 1.2 × RER ≈ 261 kcal a day: about 130 kcal from dry food (0.33 cups at 400 kcal/cup) and 130 kcal from wet (about 1.5 cans at 90 kcal).
4 kg kitten on dry food only
RER for 4 kg is 70 × 4^0.75 ≈ 198 kcal. A growing kitten needs about 2.5 × RER ≈ 495 kcal, which is 1.1 cups of a 450 kcal/cup kibble split over three meals.
Weight loss to 12 lb target, wet only
At a 12 lb (5.44 kg) target, RER is about 250 kcal. For weight loss the calculator uses 0.8 × RER ≈ 200 kcal, a little under 1.2 cans of a 170 kcal can per day.
Frequently asked questions
How much should I feed my cat a day?+
A healthy neutered adult cat needs about 1.2 × its resting energy requirement — roughly 260 kcal a day for a 10 lb cat, or about 200–220 kcal if it is inactive or prone to weight gain. Divide by the kcal per cup or can on the label to get the portion.
How many cans of wet food should a cat eat?+
It depends on the calories per can. A 10 lb neutered cat needs around 260 kcal, which is roughly three 3 oz cans at 85–90 kcal each, or about 1.5 5.5 oz cans at 170 kcal each, if fed wet food only.
Is it OK to mix wet and dry cat food?+
Yes. Many owners feed both — wet food adds moisture, dry food is convenient. Just split the daily calories so the total stays the same, which is what the wet-food percentage in this calculator does.
How much should a kitten eat?+
Kittens need about 2.5–3 times their resting energy requirement because they are growing fast. Feed kitten food in three or four meals a day until about 6 months, then two or three meals.
How do I help my cat lose weight safely?+
Feed for the target weight (about 0.8 × RER at that weight) and aim for 0.5–2% loss per week. Cats must never be starved: rapid weight loss can cause hepatic lipidosis, so involve your vet.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.