Cat size estimate calculator

Answers the question: How big will my cat become?

Kittens usually stop growing when they reach 12 months. Knowing this, we can estimate the cat size using the formula below. By entering the cat's age, in months and weeks, and the current weight, this cat size calculator will estimate the cat's weight in month 12.

If you select an option that has the same underlying value as another option, both (all) will be marked.


Estimated cat size: 15.12 kilograms
Estimated cat size: 33.34 pounds

Please keep in mind that this calculation is an estimate, but if you use this estimate and, in addition, look at your kitten's back legs, you should get a pretty good idea of your cat's size at month 12. If your cat has tall back legs compared to other cats of the same breed, you can expect your cat to go above the estimate in this calculator. Also, if you neuter your cat before adulthood, expect it to grow even bigger.

Our calculations

At Calculatorian, we are keen to share our knowledge, be transparent and open to feedback. Here are the calculations used to create this calculator. If you find an error or deficiency, contact us and we'll fix it in an instant!

Estimated cat size was calculated like this:

Estimated cat size was calculated like this:

Variables used in this formula

mo = Age in months
wk = Age in weeks
w = Weight

Depending on your choice when selecting weight measurement unit a constant is applied as the variable d in the formula.

Weight measurement unitd