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 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.

1. Calculate your kitten’s age in weeks. There are lots of online calculators that will help you do this if you’re unsure
2. Accurately weigh them
3. Find their age on the horizontal (bottom) axis and the appropriate weight on the vertical (side) axis.  Make a small dot where the two lines intersect.
4. Do this every 2-4 weeks up to 6 months of age, and then every 1-3 months until fully grown

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.

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.

The number of the centile reflects the percentage of the population (weight category) whose weight falls below that line; for example, if a cat is on the 75th centile, it means than 75% of cats in that population will weigh less (and 25% will weigh more).

Weights that follow a curved lined are considered to be ‘normal’, regardless as to whether this is the lowest or the highest growth curve. For example, a kitten’s growth can track consistently between the lowest two curves and 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.

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 in later life it is a good idea to closely monitor your kittens weight following neutering. If you 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: Mark the neuter date to your chart 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 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 should reach adulthood following a single, or in between two centile lines of their growth chart. This bodyweight should be healthy for your pet. Make sure you keep monitoring their weight 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. 

Yes! We have developed the WALTHAM™ Puppy Growth Charts into an App.

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.

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