Start with body weight

Most adult cats need roughly 40–45 kcal per kilogram of body weight per day at rest. A 4 kg neutered adult therefore needs approximately 160–180 kcal/day. That figure shifts with age, health and activity level.

You can estimate your cat's resting energy requirement (RER) with the formula used by most veterinary nutritionists: RER = 70 × (bodyweight in kg)0.75. Our feeding calculator does this for you — enter your cat's weight and life situation to get a daily target.

Life-stage multipliers

Life stageMultiplierExample (4 kg cat)
Kitten (under 6 months)3.0 × RER~450 kcal/day
Growing kitten (6–12 months)2.5 × RER~375 kcal/day
Intact adult1.4 × RER~210 kcal/day
Neutered adult (active)1.2 × RER~180 kcal/day
Neutered adult (indoor)1.0 × RER~150 kcal/day
Senior (7+ years)1.1–1.4 × RER~165–210 kcal/day

These multipliers follow guidelines published by the World Small Animal Veterinary Association (WSAVA) Global Nutrition Guidelines — the most widely adopted reference for companion animal nutrition.

Converting kcal to grams

Once you have a daily kcal target, divide by the energy density of your food. This is usually shown on the label as "kcal/kg" or "kcal/100g". If it is not on the label, the manufacturer's website usually has it, or you can call them — they are required to provide it.

Example. Your cat needs 160 kcal/day. Your dry food has 360 kcal/100g. Calculation: 160 ÷ 3.6 = 44 g per day — split across two meals.

Reading body condition, not just the scale

Bodyweight alone does not tell you whether a cat is the right size — a small cat at 4 kg might be overweight, while a large-framed cat at the same weight could be lean. Use a body condition score (BCS):

  • Too thin (BCS 1–3/9): Ribs and spine are visible. Reduce food only if under vet guidance; underweight cats may have an underlying condition.
  • Ideal (BCS 4–5/9): Ribs easily felt, slight waist visible from above. Keep feeding the same amount.
  • Overweight (BCS 6–7/9): Ribs hard to feel, no waist. Reduce daily intake by 10–15% and re-assess in four weeks.
  • Obese (BCS 8–9/9): Work with your vet. Rapid weight loss in cats can trigger hepatic lipidosis (fatty liver disease), a serious condition.

The WSAVA body condition score chart with illustrations is freely available and worth printing and keeping near your pet's food.

How often to feed

Two meals a day (morning and evening) works well for most adult cats. Kittens under six months do better on three to four smaller meals. Puzzle feeders and food-dispensing toys can slow down fast eaters and provide mental enrichment, particularly for indoor cats.

Free feeding (leaving food down all day) tends to lead to overeating in cats prone to weight gain. It also makes it harder to notice early appetite changes, which are often the first sign of illness.