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How many kittens can one female cat produce?


There are a variety of memes, common knowledge estimates, and even educated guesses about how many cats can one unaltered female produce. These estimates can range from a few hundred all the way up to 420,000!!! The calculator below will enable you to calculate a population estimates that just one pair of unaltered cats can produce. You can change the outcome of the predictions based on certain variables. Things like average lifespan, percentage of female kittens, the percentage of kittens that survive to reproduce, how many litters per year, how many kittens per litter and even the percentage of fertile females can all be changed.

Cat Reproduction

There are several estimates and averages regarding feral cat reproduction online. Studies on free-roaming cat’s reproductive capacity are actually very, very limited. In fact, the estimate that 75% of kittens born outside die is actually a result of one study of just three colonies in North Carolina! That study used all kittens found deceased or those that just disappeared up until they were 6 months old to determine that number. The estimate that female cats produce an average of 1.4 litters each year was from that very same study. That study also came up with an average litter size of 3. To be honest, we don’t know how many kittens die before sexual maturity in ‘the wild’. We don’t know how many litters are average or how many kittens per litter is born. One study of only 3 colonies, which was also part of a larger study on Trap-Neuter-Return as the other seven colonies were sterilized, is not enough information. Cats have more litters in warmer climates. If you live in the Southern United States, chances are those female cats ARE having 3 litters a year. If you live in Alaska, they may only have one litter a year. Cats can have anywhere between 1 kitten up to 9 kittens, though the average is 4. According to the ASPCA, feral cats on their own live an average of 2 years. If they’re lucky enough to have a caretaker, this number is MUCH higher as they can live to be 10 years old. I have cats in my colony who are 8 and 12 years old. The calculator below will enable you to calculate population estimates that just one pair of unaltered cats can produce. So play with the numbers!


The Population Size table of below will be updated automatically whenever you change an assumption or when you click the Update button below.

Basic assumptions:

Numerical assumptions:


The population is calculated as follows:

Population Size

The cat population calculator is courtesy of The Cat House On The Kings, a no-cage, no-kill feral cat sanctuary and kitty rescue in California.

8 thoughts on “Kitten Calculator”

  1. What an interesting page on the number of offspring one pair of cats can produce!  The statistics you present in the first part of your page are quite staggering! And it makes sense that cats living in warmer climates have more litters. I have seen that in foreign countries.  I imagine that has to do with access to food too. The statistical calculator you have provided is a helpful tool too. How do you think people can understand cats better?  Why do you think there are “cat people” compared to “dog people”? You so often hear that expression.

    1. Interesting that you should mention cat people vs. dog people.  Cat people, in general, seem to just like cats more than dogs.  It isn’t like they dislike dogs, though.  If anything, I might meet cat lovers who just don’t care much for them.  Dog lovers, on the other hand, come in three flavors, I’ve seen.  

      1. Animal lovers, but prefer dogs.

      2. Dog lovers, no real interest or experience with cats

      3. Cat HATERS, who hate cats with a fiery passion.

      It’s weird.  I know some people hate dogs, but you don’t usually see the level of hate towards our canine companions that you do towards cats.  Some theorize it is because cats are harder to understand for humans, unlike dogs whose facial expressions are quite easy for humans to grasp.

      This might partly be because dogs have been domesticated for over 40,000 years and have evolved the ability to ‘mimic’ human facial expressions.  Wolves, for example, don’t have eyebrows that move as dogs do.  Cats have only been domesticated for 9,500 years and some scientists believe they are only semi-domesticated, which means while they haven’t yet evolved the facial expression mimicry.  

      But who knows!

  2. WOW! I knew the numbers would be high but that’s pretty astounding. Thank goodness for the low-cost spay and neuter programs. I know near me, there are some rescue groups that trap feral cats, perform the spay/neuter and then rerelease them back to their homes. Between that and more responsible cat-ownership, we could hopefully make a difference!

    1. Let’s hope so, Katie!  I trap feral cats and get them fixed, try to find homes for them as well, and it is a hot mess in animal rescue right now.  People refusing to spay or neuter despite cheap resources to do so, people DUMPING their unwanted litters of kittens at farms or in the woods, where the few who survive to start multiplying, and then there are the poor kitties who were abandoned or were born outside, reproducing.  

      Let’s hope spay and neuter become more mandatory and less voluntary!

  3. That is amazing. Thanks for access to that calculator. It has always amazed me at how many kittens can make up a litter, and how often a cat can be bred. Thankfully humans cannot give birth in this way, think of the dangers to the newborns and the mother. Is it a fair assumption that if a cat is an indoor type that not only the litters will be on the larger size (fewer hazards inside), but the kittens would have a better chance at a longer survival?

    1. You are absolutely correct!  Cats that go indoors at least half the time have an increased chance their entire litter survives.  Also, regular food and shelter in a warm home will definitely increase the breeding capacity of most cats.  

      This is partly why eradicating feral cats doesn’t work and actually can cause an increase in the cat population.  If there isn’t a lot of competition for food, a cat’s litter size and frequency of reproducing will increase.  It’s nature’s way of ensuring survival.  If there is little food and too much competition, such as in winter, then breeding slows way down.  We see it all the time in wild animals. For cats, it is the same.

      That said, I don’t know how much larger indoor cat’s litter sizes are compared to outdoor cats.  But an excellent assumption!

  4. I have seen this in action. The reproductive capacity is truly staggering, but there is a plateau. The calculator doesn’t take into account adult mortality rate, and the mortality rate rises quite steeply when population density becomes too high. Speaking generally, many causes of mortality increase tremendously when an area reaches carrying capacity. There is higher conflict, therefore more fighting injuries which become infected and can actually kill a cat. Communicable diseases are far more readily transmitted from one cat to another when in close proximity to each other, and pose a serious threat of mortality to cats with weakened immune systems due to mal-nourishment when food sources are strained. Fecal waste is a problem in an overpopulated area and is a source of intestinal parasites which a cat may have no ability to stay clear of. Many of these can kill a cat or weaken immunity enough for something else to kill it. This doesn’t even touch on predation or accidental injuries.

    A managed colony, on the other hand, with a stable population well within the location’s carrying capacity, consists of cats that are capable of keeping themselves clean and healthy, not stressed by fighting and breeding, likely to have access to needed food, or to be strong and healthy enough to seek out food elsewhere.

    Please SPAY AND NEUTER. It is the compassionate choice!

    1. The Kitten Calculator is just a calculation, unfortunately. It can take into account adult mortality by reducing the years a feral cats live, of course. That said, you’re absolutely right that it doesn’t take into account the population threshold a specific area has. Unneutered toms will likely move on, and there are some migration of cats to other areas, of course. But a specific area can only hold so many cats! Still, the numbers are scary.

      That plateau you mentioned is also a higher number if people are feeding but NOT fixing those cats. More food equals more cats that area can support!

      Managed colonies definitely are healthier and happier after Trap-Neuter-Return (TNR) is performed! It IS the compassionate choice!

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