WALTHAM™ Kitten Growth Charts

How big will my cat get? When will my kitten stop growing? What should a kitten weigh? Like many new kitten owners, you might be asking yourself all these questions – and more. Owning a kitten can be a challenge. And if needle sharp teeth and tiny, yet powerful, claws weren’t enough to deal with, healthy weight gain should also be a priority.  

Created by a group of experts including veterinarians, statisticians, and nutrition scientists, WALTHAM™ Kitten Growth Charts can help pet owners and veterinary professionals monitor cats’ growth.

Why should I use them?

Just like babies, kittens that grow too quickly or slowly can suffer from lifelong health problems - therefore it’s important to ensure that kittens grow at a healthy rate.  
WALTHAM™ Kitten Growth Charts are a free user-friendly tool to allow owners to monitor their cat’s growth from 8 weeks until adulthood. 

By using the charts, you can compare your kitten’s weight and growth to the weight of other healthy kittens at the same age. This allows you to see if they’re growing at a healthy rate or spot any unusual growth so you can contact your veterinarian before it becomes an issue.

The charts are based on data from thousands of healthy young cats and are intended to be a standard for healthy growth. They have been scientifically developed in a similar manner to charts used to monitor the growth of children (e.g. the WHO growth standards), which are used by healthcare professionals around the world.

As well as the Kitten Growth Charts, we have also created WALTHAM™ Puppy Growth Charts. They are available to download, or you can use our app to track your puppy’s weight online.

Sign up in the app above to start tracking your kitten’s growth and get access to:

  • Free of charge growth charts, scientifically developed by vets and scientists using data from thousands of healthy cats 
  • Alerts if your kitten isn't growing as expected
  • Your kitten’s ideal adult weight  
  • Growth charts for male and female cats
  • Suitable for pure and mixed breed cats that have an adult weight between 2-7kg. 
  • Create unlimited pet profiles
  • Shareable growth charts that you can discuss with your veterinarian or post on social media


WALTHAM™ Kitten Growth Charts FAQs

Kittens grow very quickly in their first few months, so their date of birth is important in tracking their growth accurately. A difference of a week or two could make a big impact as to how their growth is interpreted. If you don’t know your kitten’s birthday, you could check with the breeder or if you got your kitten from a shelter, your veterinarian may be able to estimate their age. If you use an estimated date of birth, follow the curves with caution and speak to your veterinarian if you have concerns or if your kitten’s growth appears to be going off track.


Yes! The kitten growth charts have been developed using data from domestic short haired, the most common type of cat in the UK and US, rather than recognised pedigree cat breeds. However, they are suitable for all cat breeds and cross breeds that have an adult weight between 2-7kg.

You can start tracking your kitten’s growth as soon as they join your family. However, the Growth Charts are only validated for the growth curves from 8 weeks old. This means that any bodyweights you add before this will be plotted but growth lines won’t appear until you’ve added two weights, 2 weeks apart, after your kitten reaches 8 weeks.

Of course you can! If your kitten is already over 8 weeks old - don't worry. Our charts are most accurate when you start recording as early as possible, when your kitten is between 8 and 16 weeks old, as this is when they will experience their most rapid period of growth. If you start tracking after this period you will still be able to monitor your kitten's growth, it's just that it's trickier to say that your kitten's growth is on track.

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You can weigh your kitten at home using regular digital scales. You may want to put them in something e.g., a carrier or bowl to keep them still when weighing. If doing this don’t forget to subtract the weight of what you’re using from the combined weight to get the accurate weight of your kitty.
Check your scales go up in small (e.g., 1 gram) increments to accurately track your kitten’s growth

Top Tip: Try to use the same scales each time you weigh your kitten. Make sure you factor in how big they're going to grow, or how wriggly they may get!

Every 2-4 weeks up to 6 months of age, and then every 1-3 months until fully grown

It's not encouraged to weigh your kitten more frequently as things such as meals and toileting meals can make your kitten's weight appear to fluctuate. Regular (e.g., every 2-4 weeks) weight measurements over a longer period are more likely to reflect the true change in weight.

Desktop device - In the bottom right of the growth chart there is a plus button. Click this to add a new weight.

Mobile device - Make sure you've selected 'growth chart' and click the action button below

Click on the point you want to update and change the number in the weight box. Click 'Add weight' to update the growth chart.

If the date is incorrect, you will need to delete the point and re-enter it

When adding a new kitten, you can choose between kg and lbs. You can change this later by selecting the kg/lbs toggle in the top right of the growth chart.

Sorry to hear your kitten is unwell! We recommend you continue weighing them even though they’re not feeling their best.

Some illnesses, such as gastroenteritis, can lead to a temporary halt in growth. In most cases your kitten should catch up again to the original centile line. If this doesn't happen, they're unwell for a long period of time, or they cross 2 or more centile lines, please contact your veterinarian.

Top Tip: make a note of when they were unwell in your calendar in case you need to discuss with the veterinarian in the future.

The colour areas of the chart will appear once two bodyweights have been added that are 2 weeks apart, and the first is when the kitten is 8 weeks old or over. The earliest this will appear is therefore when the kitten is 8 weeks old. Still having problems, contact us.

Your kitten's growth chart includes curves, which are centile lines. These represent the expected range of normal growth for cats based on the data from thousands of healthy cats.

For the WALTHAM™ Digital Growth Charts the centile number has been replaced with the adult body weight for that curve. Growth charts with the centile numbers on are available to download in resources for veterinary professionals. 

Weights that follow a curved line are considered to be ‘normal’, regardless as to whether this is the lowest or the highest growth curve. A kitten’s weights do not have to follow the central curve to have healthy, normal growth.

Typically, a healthy kitten’s weights will stay in the same part of the chart throughout growth. However, some healthy kittens track more closely to the curved lines than others.

By tracking weight and comparing them to the growth curves, problems can also be identified and managed more quickly. For example, kittens crossing growth curve (or centile) lines upwards are growing quicker than expected, whilst those crossing downwards are growing more slowly than expected. Crossing these lines can occur in healthy cats, however it's more likely to occur when there is a health issue or problem with nutrition and may indicate that a trip to the veterinarian may be needed.

Further reading: WALTHAM™ pocket book of healthy weight maintenance for dogs and cats

The kitten growth charts will colour different areas of the chart once enough weight measurements have been added for your kitten. The colouring is to help you understand what the expected growth trajectory is for your kitten, and when to be cautious, or seek veterinary advice.

Green zone – this is the ideal area for your kitten’s weight. This area has been selected based on 3 measurements 2 weeks apart after 8 weeks old when you started to track your kitten’s growth. If your kitten’s weight is in the green band (between two growth curves, or centiles) they are growing the same rate as other healthy kittens. 

Orange zone – These areas highlight the neighbouring areas to the green, or ideal zone, for your kitten. If your kitten’s weight crosses into these areas, it means they are growing a little faster/slower than expected for healthy growth.  This isn’t something to be concerned about, as it may represent healthy growth for your pet, however, keep weighing them regularly to see how their weight continues to change and track on the chart.

Red zone – This area highlights when weight measurements for your kitten are a concern. If you add new weights and they are in the red zone, check that the weight measurement is accurate, and the date is correct. Keep an eye on your kitten – take another weight measurement 2 weeks later. There are notifications in the charts to let you know what action you should take. If you have any concern, please seek advice from your veterinarian. 

Most kittens reach their mature adult weight by 52 weeks of age. However some kittens, in particular those that have a healthy adult bodyweight above average, may continue to grow a little longer. 

When your kitten reaches the end of their growth curve, this is when they are considered fully grown. In our study looking at the growth data of thousands of healthy cats, we saw the majority had finished growing by 78 weeks. 

Neutering can impact growth. We found neutered female kittens require portion control to stay at a healthy weight.

To develop the charts, only the data from entire cats was used. This doesn't mean the growth charts are not appropriate for neutered kittens. However, because neutering is a risk factor for becoming overweight/obese later life it is a good idea to closely monitor your kitten’s weight following neutering. If your kitten’s weight after neutering deviates from its growth centile you should seek veterinary advice to check that your kitten is developing as it should do.

Top Tip: You can add neuter date to your kitten’s profile so you can see if it impacts your kitten’s growth.

Body condition score charts are a great way to check if your cat is in ideal condition. 

If you haven't been trained and gained experience measuring lots of different cats, they can be tricky to use and may result in a cat being scored incorrectly. 

The WALTHAM™ Kitten Growth Charts can be used by anyone without training and help owners track if their kitten is gaining a healthy amount of weight.

Top tip: when you take your cat to the veterinarian ask them to body condition score your cat (and explain why they have given that score) so you get used to what your cat feels like at a healthy weight.

Once you have taken enough measurements (at least 3 after 8 weeks of age, spaced a minimum of 2 weeks apart),  so that you know the growth curve line that your kitten is following, you could then use this to predict expected adult weight, assuming that your kitten continues to grow at a healthy rate.

Your kitten’s adult weight should be in the green zone. Make sure you keep monitoring their weight into adulthood as this should not fluctuate too much. If it changes by more than 5%, seek veterinary advice.

The charts are based on data from thousands of healthy young domestic shorthair kittens and are intended to be a standard for healthy growth. These cats had their bodyweight recorded during routine trips to one of the Banfield Pet Hospitals in the USA. They all remained healthy and in ideal body condition during their first 2.5 years of life. Once developed, the charts were validated by comparing the growth curves to the growth pattern of other healthy cats and cats that were overweight, or underweight or had diseases associated with abnormal growth.

The methods behind the creation and validation of the kitten Growth Charts have been published in PLoS One, an independent international, peer-reviewed scientific journal. They were created by a group of experts including veterinarians, statisticians, and nutrition scientists. The scientific approach to develop these charts is similar to the one used to monitor the growth of children (e.g. the WHO growth standards), which are used by healthcare professionals around the world. 

Interested? Read more about the science behind the charts

Yes! You can track your puppy’s growth from the same app. Simply add a new pet and select “Puppy” instead of “Kitten” to monitor both of your furry friends at the same time. 

More info on the Puppy Growth Charts

We used data from entire cats to create the growth charts because neutering can influence growth. This doesn't mean the growth charts are not appropriate for neutered kittens. However, because neutering is a risk factor for becoming overweight/ obese in later life it is a good idea to closely monitor your kittens weight following neutering. If your kitten’s weight after neutering deviates from its growth centile you should seek veterinary advice to check that your kitten is developing as it should do.

We'd love to hear from you! Please email us via the contact us form and select 'our institute' as the option.

Resources for veterinary professionals

With unlimited pet profiles, veterinary teams can create their own account to add kittens or encourage pet owners to sign up and track their own pet’s progress. 

PDF copies of the charts are still available below. These can be downloaded, printed, and used to track a kitten’s growth. Puppy Growth Charts are also available in the app and as PDFs.

Using WALTHAM™ Kitten Growth Charts, veterinary professionals can: 

  • Reassure owners on diet and how much to feed a kitten
  • Identify kittens that are gaining weight too quickly and are at risk of becoming overweight
  • Identify kittens that are gaining weight too slowly and may be under-fed or a suffering from a growth condition
  • Recommend changes to a kitten’s nutrition plan e.g., decreasing or increasing food if a kitten is growing too quickly or too slowly
  • Justify recommending further investigations if a growth disorder is suspected

Below you can find a range of documents designed to support veterinary professionals using pet growth charts in their clinics. 

Please note we have chosen to provide our charts only in a PDF format and are unable to provide physical copies of any parts of the growth chart kits. If you need to calculate age, we recommend using an online calendar.

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