Cat weight chart by age, and when weight loss needs a vet

The average cat weighs about 4 kg, but there is no single right weight for every cat; your vet can tell you what is healthy for yours. The PDSA says to take your cat to the vet if they suddenly start losing weight, or lose weight very quickly. Slow loss is easy to miss, so write down dated weigh-ins.

How much should my cat weigh?

Cats Protection gives the average weight for a cat as approximately 4 kg (9 lb), and notes that it can vary depending on many factors. It also says your vet will be able to tell you what weight is healthy for your cat.

The PDSA agrees that there is no one exact ideal weight for cats. It varies by size, age and breed, so there is no single number that suits every cat.

That is why the number worth asking about is your own cat's, from a vet who can see and feel them.

Is there a cat weight chart by age?

In the veterinary sources we checked, we did not find an adult cat weight chart by age. We would rather say that plainly than invent a table that looks authoritative and is not.

What does exist is useful in two parts. The first is a kitten ageing chart for the earliest weeks, published to help estimate a young kitten's age. The second is the adult average above, about 4 kg, a starting point rather than a target.

Cats Protection publishes these approximate weights to help estimate a young kitten's age. They are not a target. Ask your vet whether your kitten's growth is on track.

Source: Cats Protection, kitten ageing chart, accessed 19 October 2026. The chart is published to help estimate a young kitten's age.

Beyond the first couple of months, growth varies from kitten to kitten, so your vet's weigh-ins at check-ups are the best guide.

How do vets tell if my cat is a healthy weight?

Vets weigh your cat and also assess body condition, a hands on and visual check of how much fat your cat is carrying.

The PDSA describes five things you can check at home:

• The ribs. You should feel them with light pressure, with the skin moving freely over them.
• The spine and hip bones. You should be able to feel them, but not see them.
• The base of the tail. There should be no build-up of fat there.
• The tummy. It should tuck in rather than bulge.
• The waist. Seen from the side and from above, there should be a visible waist.

International Cat Care uses a body condition score of 1 to 5, where 1 is very thin, 3 is ideal and 5 is obese. The score is your vet's call, and it takes practice. If you are unsure what you are feeling, ask your vet to show you on your own cat.

Why is my older cat losing weight?

Only your vet can tell why, because there are many possible causes, but the PDSA is direct: if your cat suddenly starts losing weight, or loses weight very quickly, take them to the vet.

Cats Protection adds that if you are concerned about a change in your cat's weight, speak to your vet for advice.

Weight loss can be easy to explain away. A cat who seems a little lighter to lift, or smaller than your memory of them. Any weight loss you cannot explain is a reason to book a visit, even if your cat seems well in themselves.

Why slow weight loss is easy to miss

Take an example. A 13 year old cat weighed 4.2 kg last year and weighs 3.9 kg today. That is a change of 300 g, which does not sound like much, and because you see your cat every day, the cat in front of you looks the same as yesterday.

Readings over time are the story, which is why Cats Protection suggests tracking your cat's weight at home between vet visits. RSPCA Australia recommends a check-up by your vet at least once a year, and notes that your cat's weight will also be monitored during these visits. Cornell University College of Veterinary Medicine quotes a vet who recommends that owners watching their cat's weight use a baby scale to monitor it at home.

To make your readings easy to compare:

• Weigh at the same time of day on the same scales, so you are comparing like with like.
• No pet or baby scale at home? Weigh yourself holding your cat, then weigh yourself alone, and take the difference.
• Write each reading down with the date, even when nothing changes. A steady line is useful information too.

What to note for your vet

When weight comes up at a visit, these details help your vet see the whole picture:

• Recent weights, with dates, rather than a best guess.
• When you first noticed a change, if you have.
• Eating and drinking, in your own words.
• Drinking, whether it seems like more or less than usual.
• Toileting changes.
• Energy and behaviour.
• Anything else that changed around then, such as food or routine.

You do not need to work out what any of it means. That is your vet's job. Your part is the noticing.

How My Furly helps you keep track

My Furly is a place to keep your cat's health story, so the trend is there when you need it.

A weight chart over time. Add your cat's weight whenever you weigh them. Once there are two readings, My Furly shows them on a chart, with a simple label for the last two weights: Increasing, Decreasing or Stable. The label describes your own readings. It is not a judgement about what your cat should weigh. That stays with your vet.

Dated notes beside the numbers. Add a dated note about eating and drinking, or anything else that changed. Months later, you can see what changed and when.

A private link for your vet. When you choose to, you can create a private link with an access code and send it to your vet. They see your cat's weight history alongside the rest of the record, so the conversation starts from the trend rather than a single reading. You can replace the link at any time.

Ask Furly before a weigh-in. Furly, the companion inside My Furly, knows your cat's own record. You can ask what is worth noting before a weigh-in, or how to put a question to your vet. Furly is not a vet, and is built to point you to one when it matters.

None of this replaces your vet. It means you arrive with the before as well as the now.

Frequently asked questions

How much should my cat weigh?

The average weight for a cat is approximately 4 kg (9 lb), but there is no single right weight. It varies with many factors, and your vet can tell you what is right for your cat.

Is there a cat weight chart by age?

We did not find an adult cat weight chart by age in the veterinary sources we checked, and we would rather not invent one. What exists is a kitten ageing chart for the first weeks, and the adult average of about 4 kg. Your vet's weigh-ins are the best guide.

How much should a kitten weigh?

Cats Protection's kitten ageing chart gives about 100 g for a newborn, rising to about 900 g at around 8 weeks. It is published to help estimate a kitten's age, not as a target. Beyond the first couple of months, growth varies from kitten to kitten. Ask your vet whether growth is on track.

How can I tell if my cat is a healthy weight?

Ask your vet to weigh your cat and assess body condition. The PDSA's home checks look for ribs you can feel with light pressure, a spine and hip bones you can feel but not see, no fat at the base of the tail, a tummy that tucks in, and a waist visible from the side and above.

When does weight loss in a cat need a vet?

If your cat suddenly starts losing weight, or loses weight very quickly, take them to the vet. Any weight loss you cannot explain is a reason to book a visit, even if your cat seems well in themselves.

How often should I weigh my cat?

Your vet can suggest how often suits your cat. What matters most is weighing regularly and writing each reading down with the date.

Sources

• Cats Protection. Is my cat the correct weight? 12 October 2022. www.cats.org.uk/cats-blog/is-my-cat-the-correct-weight. Accessed 19 October 2026.
• Cats Protection. How old is that kitten? Use our kitten ageing chart. www.cats.org.uk/help-and-advice/pregnancy-and-kitten-care/kitten-ageing-chart. Accessed 19 October 2026.
• PDSA. Vet Q&A: How do I know if my cat is too fat? 30 December 2019. www.pdsa.org.uk/what-we-do/blog/vet-qa-how-do-i-know-if-my-cat-is-too-fat. Accessed 19 October 2026.
• International Cat Care. Obesity in Cats. Updated 26 September 2025. icatcare.org/articles/obesity-in-cats. Accessed 19 October 2026.
• RSPCA Australia Knowledgebase. How can I be a responsible cat owner? Updated 9 May 2024. kb.rspca.org.au/knowledge-base/how-can-i-be-a-responsible-cat-owner. Accessed 19 October 2026.
• Cornell University College of Veterinary Medicine. Obesity. www.vet.cornell.edu/node/4071. Accessed 19 October 2026.

More on your cat's weight

For the dog version of this guide, see How much should my dog weigh? A healthy weight guide. For why your cat's own normal matters more than any average, see You know your pet best. Furly remembers the rest. For how that history changes a vet visit, see Your vet, already up to speed before you sit down. For how long is too long, see Cat not eating: how long is too long, and when to see a vet.

Start keeping your cat's weight history at myfurly.ai.

A gentle note

Furly helps you organise and understand your pet's history, and prepares you for the vet. It is not a diagnosis tool and does not replace professional care. If something worries you, or your cat is losing weight, speak to a licensed vet.