How much should a kitten weigh? It depends on age, breed, and sex — and it changes every few weeks, which is why the question needs a chart, not a single number. A typical kitten weighs about 0.7 to 1 kg at 8 weeks, about 2 to 3.5 kg at 6 months, and about 3 to 5 kg at 12 months, but a large breed such as a Maine Coon can weigh more at every age and keep growing for 2 to 4 years, while a small breed such as a Singapura may never weigh more than 2 to 3 kg as an adult. This guide is the kitten cat weight calculator in words: the growth chart by age, the expected adult weight by size and breed, how to weigh a kitten and track its growth, and what to do when a kitten is underweight or overweight.
Weight is the single most useful number an owner can track in a kitten, because it is easy to measure, it changes fast enough to show a trend in weeks rather than months, and it reflects almost everything else — food, health, and growth. A kitten that is gaining steadily is growing well. A kitten that is not gaining, or that is losing weight, needs a vet check, not just more food. Weigh every two weeks, write the number down, and watch the line, not the single reading. This guide explains how to do that properly, and what the numbers mean at each age.
Kitten weight chart by age
The table below gives the typical weight range for a kitten at each age, for a small to medium breed. It is a rough guide, not a rule: individual kittens vary, and breed matters more than age alone. A large-breed kitten will be above the top of the range at every age, and a small-breed kitten may be below the bottom — and both can be perfectly healthy. What matters is the trend: steady gain, week by week, within the range for the kitten's breed.
| Kitten age | Typical weight |
|---|---|
| 8 weeks (2 months) | About 0.7–1 kg |
| 3 months | About 1–1.5 kg |
| 4 months | About 1.5–2.5 kg |
| 6 months | About 2–3.5 kg |
| 9 months | About 3–4.5 kg |
| 12 months | About 3–5 kg |
As a rough rule, a kitten gains about 100 g a week in its first months, and reaches about half its adult weight by around 4 to 5 months, but that is a very rough guide, not a rule — growth is fastest in the first weeks and slows towards the end of the first year. A kitten that is gaining steadily, even if it is at the bottom of the range, is usually growing well. A kitten that has stopped gaining, or that is losing weight, needs a vet check promptly. The kitten weight predictor estimates adult weight from the kitten's current weight and age, and the kitten cat age calculator guide explains the life stages the growth follows.
Expected adult weight by size and breed
The expected adult weight is the target the growth chart is aiming at, and it depends on size and breed. Small cat breeds, at 2 to 4 kg as adults, include the Singapura at 2 to 3 kg, the Munchkin at 2 to 4 kg, and the Cornish Rex at 2 to 4 kg. Medium breeds, at 3 to 6 kg as adults, include most domestic and pedigree cats — the British Shorthair at 4 to 8 kg, the Siamese at 3 to 5 kg, and the Bengal at 4 to 7 kg. Large breeds, at 5 to 11 kg as adults, include the Maine Coon at 6 to 11 kg, the Ragdoll at 5 to 9 kg, the Norwegian Forest Cat at 5 to 9 kg, the Turkish Van at 4 to 9 kg, the Siberian at 4 to 9 kg, and the Savannah at 5 to 11 kg. Those ranges are the breed-standard ranges where they are confidently known, and size-class estimates where they are not — the same distinction this site uses on every breed page.
Large breeds take longer to reach their adult weight: a Maine Coon, a Norwegian Forest Cat, or a Ragdoll can take 2 to 4 years to finish growing, while a small or medium breed is usually an adult by about 12 months. That is why the growth chart above stops at 12 months — after that, the kitten is an adult in most breeds, but a large breed is still growing, and its weight should still be tracked every month or two until it is stable. If you do not know your kitten's breed, use the size ranges as a rough guide and ask your vet to judge the kitten's frame: a stocky kitten will weigh more than a lightly built one of the same age, and both can be healthy.
How to weigh a kitten and track growth
Weigh the kitten every two weeks in its first year, at the same time of day, on the same scales, and write the number down with the date. Kitchen scales work well for a small kitten: put a basket or a towel on the scales, zero them, and put the kitten in. For a larger kitten, bathroom scales work if you weigh yourself holding the kitten and then weigh yourself alone and subtract — but kitchen scales are more accurate, and accuracy matters when the kitten only weighs a kilo or two. Keep a simple chart — date and weight, in a notebook or a spreadsheet — so you can see the line over weeks, not just the latest number.
Feel the kitten as well as weighing it: you should feel the ribs easily under a thin layer of fat without pressing hard, and you should see a waist from above, even in a kitten. A kitten that is gaining weight but losing condition — ribs harder to feel, no waist — is gaining fat, not growing. A kitten that is gaining steadily and feels lean and muscular is growing well. If the line on your chart flattens or falls for two weigh-ins in a row, mention it to your vet at the next check, or sooner if the kitten is also eating less, sleeping more, or has diarrhoea or vomiting. The cat ideal weight calculator gives a starting range for an adult cat, and the kitten cat food calculator guide gives the calorie tables that make growth feeding practical.
What to do if a kitten is underweight
If your kitten is underweight — below the range for its age and breed, or not gaining for two weigh-ins — do not simply feed more of the same food and hope. First, ask your vet to check for the causes: worms, which are common in kittens and can stop growth; an infection; a food the kitten does not digest well; or a health problem that needs treatment. A vet check, including a worming treatment and a check for parasites, is the first step, not the last. Kittens should be wormed regularly in their first year, and your vet will set the schedule. Once health causes are ruled out or treated, the feeding plan is to offer more calories in a form the kitten will eat: a little more food, split into three to four small meals, and a kitten food labelled complete and balanced.
Weigh weekly while you are working on weight gain, not every two weeks, so you can see the trend quickly, and write the numbers down. If the kitten will not eat, or eats and still does not gain, go back to the vet promptly: a kitten that will not eat is always worth a vet visit, and the cause is often treatable when it is caught early. Do not give a kitten cow's milk, human baby food, or supplements without veterinary advice — most cats cannot digest lactose, and supplements can unbalance a diet that is already complete. Do not overfeed to make the kitten grow faster: rapid growth and excess weight in kittenhood set up weight problems for life.
What to do if a kitten is overweight
If your kitten is overweight — above the range for its age and breed, or with ribs you cannot feel — the plan is gentle and slow. Cut food by about 10%, keep treats under 10% of daily calories, and re-weigh in two weeks. Do not put a kitten on a crash diet, and do not use an adult food or a weight-loss food without your vet's agreement, because a kitten needs the protein, fat, and calcium in a kitten food to grow properly — the amount should come down, not the quality of the food. Keep play regular and active: a kitten that plays hard every day burns more and builds muscle, and play is also how a kitten learns and stays confident.
Ask your vet to check growth against the expected adult weight for the kitten's breed, and to set a target weight and a timescale. A kitten that is overweight at 6 months is much more likely to be an overweight adult, and an overweight adult cat is more likely to develop diabetes, joint problems, and urinary issues — so the effort in kittenhood pays for itself many times over. The cat food calculator works out daily calories by weight and life stage, and the cat age in human years chart puts the kitten year in context, with the human-age equivalents at each age.
For related reading, see the kitten weight predictor, the kitten cat age calculator guide, the kitten cat food calculator guide, the cat ideal weight calculator, the kitten cat lifespan guide, the cat food calculator.
Frequently asked questions
How much should a kitten weigh at 8 weeks?
About 0.7 to 1 kg for a small to medium breed, as a rough guide. Large-breed kittens can weigh more, and small-breed kittens less. What matters is the trend: steady gain, week by week, within the range for the kitten's breed.
How much should a kitten weigh at 6 months?
About 2 to 3.5 kg for a small to medium breed, as a rough guide — roughly half its adult weight. A large-breed kitten such as a Maine Coon can weigh more, and a small breed such as a Singapura less. Weigh every two weeks and watch the line, not the single reading.
How fast should a kitten gain weight?
As a very rough guide, about 100 g a week in the first months, slowing towards the end of the first year. Growth is fastest in the first weeks and slows as the kitten approaches adulthood. A kitten that has stopped gaining, or that is losing weight, needs a vet check promptly.
When is a kitten fully grown?
Most cats are adults by about 12 months, but large breeds such as Maine Coons, Norwegian Forest Cats, and Ragdolls can take 2 to 4 years to finish growing. A cat is an adult when it has finished growing and its weight has been stable for a few months — ask your vet to confirm it at a routine check.
How do I know if my kitten is overweight?
Feel the ribs: you should feel them easily under a thin layer of fat without pressing hard. Look from above for a visible waist. If you cannot feel the ribs or there is no waist, the kitten is probably overweight — cut food by about 10% and ask your vet to check growth against the expected adult weight.
What should I do if my kitten is not gaining weight?
Ask your vet to check for the causes — worms, infection, or a food the kitten does not digest well — before simply feeding more. Weigh weekly while you work on it, and go back to the vet promptly if the kitten will not eat or still does not gain.
Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.