How Much Should You Feed Your Cat? Vet-Approved Guide

Cats are notoriously independent animals — but when it comes to food, they rely entirely on their owners to get the quantity right. Overfeeding is the single most common nutritional mistake made with domestic cats. An estimated 59% of cats in the UK are overweight or obese, and the consequences are serious: diabetes, arthritis, urinary disease, and a significantly shortened lifespan.

Unlike dogs, cats are obligate carnivores — their nutritional requirements are specifically tied to animal protein and fat, and their calorie needs are calculated differently. This guide explains the method vets use to calculate daily calorie requirements for cats, covering every life stage from kitten to senior.

How cat calorie needs are calculated: the RER formula

The starting point for any cat feeding calculation is the Resting Energy Requirement (RER) — the calories needed at complete rest to sustain vital functions. The formula is the same as used for dogs:

A life-stage multiplier is then applied to the RER to account for growth, activity, reproductive status, and age:

Notice that the multipliers for cats are considerably lower than those for dogs — particularly for neutered adults (1.2× vs 1.6×). This reflects the cat's naturally lower metabolic rate relative to body weight and its tendency to be less active than dogs. Neutering reduces a cat's energy needs by roughly 25–30%, which is why weight gain after neutering is so common when owners continue feeding the same pre-neutering amounts.

Feeding kittens (0–12 months)

Kittens are in a state of rapid development from birth to twelve months. In the first six months, a kitten's energy needs are 2.5× RER — more than double what an adult cat of the same weight would require. This fuels the growth of bones, muscles, organs, and the immune and nervous systems.

Between six and twelve months, growth slows and the multiplier drops to 2.0× RER. It is important to keep kittens on a diet specifically formulated for kittens during this entire period, as kitten food is higher in protein, fat, and key nutrients like taurine and DHA that are critical for healthy development.

Feed kittens three to four small meals per day up to the age of six months. After six months, two meals a day is sufficient. Avoid free feeding — leaving food out throughout the day makes it difficult to monitor intake and can encourage overeating.

Feeding adult cats (1–10 years)

Adult cats have considerably lower energy needs than most people realise. A typical neutered indoor cat weighing 4–5 kg needs only around 200–240 kcal per day. This is easy to overestimate — a standard 85g pouch of wet food contains roughly 70–90 kcal, and a cup of dry food typically contains 300–400 kcal.

Many cat owners, particularly those who free feed, significantly overfeed their cats simply because portions are not measured. Switching to weighed, measured meals is one of the most effective single changes you can make to manage your cat's weight.

Activity level also matters. Outdoor cats that hunt and roam may need 20–30% more calories than indoor sedentary cats. Our feeding calculator includes an activity level adjustment that handles this automatically.

Feeding senior cats (10+ years)

Cats are considered senior from around ten years of age. Senior cats generally have lower activity levels and a slower metabolism, bringing calorie needs down to 1.0–1.2× RER. However, some older cats — particularly those with hyperthyroidism, inflammatory bowel disease, or dental issues — can lose weight rapidly and actually require higher calorie diets or more palatable food formats.

Monitoring your senior cat's weight monthly is strongly recommended. Unexplained weight loss in a senior cat warrants a veterinary check, as it is often the first visible sign of an underlying health condition.

Wet food vs dry food for cats

Cats have a naturally low thirst drive — in the wild, they obtain most of their hydration from prey. This makes wet food particularly beneficial for cats, as it contributes significantly to daily water intake and helps support kidney and urinary tract health. Many vets recommend that cats eat at least some wet food daily for this reason.

That said, dry food has practical advantages — it is cheaper, easier to store, and does not spoil if left out. Many cat owners feed a combination of both. For a full breakdown of the trade-offs, read our guide: Dry vs Wet Pet Food: Which Is Better for Your Pet?

Regardless of food type, always enter the specific kcal/cup or kcal/100g from your packaging into our feeding calculator — do not use generic average figures, as calorie density varies enormously between brands.

How to assess your cat's body condition

The calculation gives a target — body condition scoring tells you whether you are hitting it. At an ideal body condition, you should be able to feel your cat's ribs easily without pressing hard, but not see them. From above, there should be a subtle waist visible behind the ribcage. From the side, the abdomen should tuck up slightly rather than hanging down.

If your cat's ribs are hard to feel, their belly sags, or there are prominent fat pads at the base of the tail, they are likely overweight and portions should be reduced by 15–20%, using the overweight body condition setting in our calculator.

Common cat feeding mistakes

Free feeding dry food all day. Cats will often overeat when given unlimited access to food, particularly kibble, which is energy-dense. Measured meals at set times give you much better control over intake.

Not adjusting after neutering. Neutering reduces energy requirements by roughly 25–30%. Portions should be reduced at the time of neutering to prevent the very common post-neuter weight gain.

Feeding the same amount as before weight changes. If your cat gains or loses weight, their portions need to change. Recalculate using the calculator whenever you notice a change in body condition.

Assuming all cat foods are the same calorie density. They are not — the difference between a light formula and a high-energy formula can be 40–50% in kcal/100g. Always check the label.

Also read: How Much Should You Feed Your Dog? — the same RER method explained for dogs with their life-stage multipliers.

Disclaimer: This article is for informational purposes only and does not constitute veterinary advice. Always consult a qualified veterinarian for guidance specific to your pet.