Kitten Growth & Weight Calculator

Kitten Growth Guide

Normal Kitten Growth Rates

Newborn kittens weigh 90–110g. Healthy kittens gain approximately 10–15g per day (100g per week) in the first months. At 8 weeks (weaning age): approximately 800g–1kg. At 3 months: 1.2–1.5kg. At 6 months: 2.5–3.5kg (roughly half adult weight). Kittens are usually fully grown by 12–18 months for domestic breeds; Maine Coons and Ragdolls may not fully mature until 3–5 years. Weigh kittens weekly to catch growth problems early.

Predicting Adult Weight

A rough formula: adult weight ≈ kitten's weight at 16 weeks × 2, or at 10 weeks × 2.5. More accurate: most domestic kittens reach adult weight at approximately 40 weeks, so the multiplier from any week can be estimated from growth curves. Male cats are typically 20–30% heavier than females of the same breed. Large-breed males (Maine Coon) can reach 8–12kg; domestic shorthair females typically 3.5–5kg. The father's size is often a better predictor of adult male weight than the mother's.

When to Be Concerned

Seek veterinary advice if: kitten loses weight or fails to gain for more than 2–3 days, weight gain stops in the first 4 months, kitten is more than 10% lighter than littermates at the same age, or significant lethargy, refusal to eat, vomiting, or diarrhoea occurs. In the first weeks, kittens cannot maintain their own body temperature — chilling is the most common cause of failure to thrive. Keep kittens warm (29–32°C in the first week, reducing to 24°C by week 4).

Nutrition for Kittens

Kittens have very different nutritional requirements from adult cats: higher protein (minimum 30% dry matter), higher fat, higher calcium and phosphorus for bone development, and essential amino acids including taurine (deficiency causes heart disease) and arginine. Always feed kitten-specific food until 12 months (or 18 months for large breeds). Wet kitten food supports hydration and is nutritionally appropriate — most cats do not drink enough water with dry-food-only diets. Avoid raw feeding i