How Big Will My Cat Get Calculator 🐱

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Anna Szczepanek, PhD and Alexa Ruiz
Last updated: Feb 10, 2022

You've just found your new favorite how big will my cat get calculator. Our tool not only estimates the future weight of your favorite feline - it'll also show you how to tell how big a kitten will get and guide you through all the necessary calculations, step by step! 🐱

Read on to discover:

  • When do cats stop growing;
  • How big do cats get; and
  • When does puberty start for your cat.

How to calculate how big will my kitten get?

It's actually pretty easy! All you need to predict how big will your kitten get is:

  • Your cat's current age; and
  • Your cat's current weight.

If you've already gathered all the information, let's use the equation taken from our how big will my cat get calculator:

Final size = (Weight / Age) * 32


  • Age is given in weeks.
💡 At 16 weeks old, your cat will reach half of its final weight.

In what follows, we will discuss how big do cats get.

Fancy some other catculations? 🙀Take a look at our other feline tools:

How big can a cat get?

  • The biggest domestic cat ever weighed over 21.3 kg (46 lb), while the biggest feline on earth, a liger (lion + tiger mixture) called Hercules, weighed over 412.2 kg (922 lb)!

  • The biggest domestic cat breeds are Siberian cat, Ragamuffin, and Ragdoll.

  • The Guinness World Records recognizes the longest domestics cats. The trophy currently belongs to a 123 cm (48.5 in) long Stewie.

As you can see, the answer to the question how big do cats get is not as straightforward as it seems!

💡 Usually all the northern breeds that originated in colder climates tend to be larger. That's because it's easier to keep yourself warm when your body surface to body [volume](calc:195) [ratio](calc:258) is the lowest possible (aka it's better to be large and [round](calc:1067)).

If you love all the animals equally, we've got good news for you - a bunch of dog-related tools that will get you moving again right after you finish the how big will my cat get calculator. 🐕

How to use the how big will my cat get calculator?

It's probably not possible to make it any easier!

  1. Enter your cat's age.
  2. Enter your cat's weight.
    You may choose between imperial and metric units - we've got everything that you need!
  3. Hey, you're already there! Enjoy your results. 🎉


When do kittens stop growing?

Many sources say that kittens become adult cats after approximately 1 year of growing - in reality, this process varies heavily and ranges from 32 to 52 weeks.

How to calculate my cat's puberty start?

The calculation is short and simple:

  1. Find exactly when your cat was born.
  2. Add the number of months, depending on your cat's sex:
    • If it's a girl, add 6 months.
    • If it's a boy, add 5 months.
  3. This method allows you to estimate the earliest possible start of your cat's puberty. Watch out for sexual maturity signs, such as urine marking or increasing affection and vocalization.

How to tell that my cat has already stopped growing?

Cats usually stop growing between the 8th and 12th month of their lives.

If your cat's over 1 year old, and you can clearly see the signs of sexual maturity (puberty), you can be almost certain that your cat's an adult.

If your kitten's younger than that, hop on board the how big will my cat get calculator and compute the final size of your favorite tabby!

Łucja Zaborowska, MD, PhD candidate
Your kitten's age
Final size
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