Cats age much faster than humans in their first couple of years.
A one-year-old cat is roughly equivalent to a 16-year-old human. In their second year they mature at a slightly slower rate with a two year old cat being equivalent the of a 24 year old human.
After cats have matured a slower rate of 4 cat years to every human year is a more accurate scale. With a 4 year old cat being the equivalent of a 32 year old human and a 6 year old cat being the equivalent of a 40 year old human.
Indoor cats live to an average of 15 years which is equivalent to a human age of 76.
Cat Age Calculator:
Cat Age In Human Years Conversion Table
While it is not an exact science the table below shows how cats mature at a much faster rate than humans do:
|Cats Age||Human Equivalent||Life Stage|
|1 month||1 year||Kitten|
|2 months||3 years||Kitten|
|3 months||5 years||Kitten|
|4 months||7 years||Kitten|
|5 months||9 years||Kitten|
|6 months||11 years||Kitten|
|12 months||16 years||Young Adult|
|18 months||20 years||Young Adult|
|2 years||24 years||Young Adult|
|3 years||28 years||Physical Prime|
|4 years||32 years||Physical Prime|
|5 years||36 years||Physical Prime|
|6 years||40 years||Physical Prime|
|7 years||44 years||Mature|
|8 years||48 years||Mature|
|9 years||52 years||Mature|
|10 years||56 years||Old|
|11 years||60 years||Old|
|12 years||64 years||Old|
|13 years||68 years||Old|
|14 years||72 years||Old|
|15 years||76 years||Very old|
|16 years||80 years||Very old|
|17 years||84 years||Very old|
|18 years||88 years||Very old|
|19 years||92 years||Very old|
|20 years||96 years||Very old|
|21 years||100 years||Very old|
|22 years||104 years||Very old|
|23 years||108 years||Very old|
|24 years||112 years||Very old|
|25 years||116 years||Very old|
|38 years*||168 years||Very old|
*the oldest cat who ever lived.
In the first month of your cats life they mature by the equivalent of one human year.
Over the next few months the rate at which they mature speeds up to two human years for every month of your cat’s life.
By the age of 6 months old they are equivalent to an 11-year-old human.
Once they reach the age of 6 months old the rate of maturing slows down, with cats maturing at a more leisurely rate of 4 human years to every 6 months.
By the time they reach 18 months old they are fully grown and are equivalent to a 20-year-old human.
The 6 months / 4 year rate continues until they are two years old (24 years old in human years).
From here on your cat will age by 4 human years for every one cat year.
A few landmark cat ages and their human equivalent include:
- 3.5 cat years = 30 human years
- 6 cat years = 40 human years
- 8.5 cat years = 50 human years
- 10 cat years = 56 human years
- 11 cat years = 60 human years
- 21 cat years = 100 human years
The average cat will live to the age of 15 years, the equivalent of 76 in human years.
The record for the oldest cat is 38 years, a massive 168 years in human years.
The average outdoor cat will live to 5.5 years, equivalent to a 38 year old human.
Not sure how old your cat is? Read our article on how to tell a cats age.
Average Cat Life Expectancy
Cats life expectancies vary from breed to breed, things such as whether they have been neutered also impact their life expectancy.
As a general rule mixed breed cats are often hardier and have longer than average life spans.
The factor which has the biggest impact on the length of your cats life is whether it is an indoor or an outdoor cat:
- An indoor cat can expect to live to an average of 15 years.
- Outdoor cats live an average of 5.5 years.
Read our article on how long do cats live for more information.
The human age equivalent of a 15 year old cat is 76.
How Is Cat Age In Human Years Calculated?
76 is the average lifespan for humans globally (it is closer to 80 in the western world).
Cat ages in human years are calculated based on average lifespans.
For example 76/15 = 5, meaning that one human year equals 5 cat years. With a bit of adjustment to accomodate the faster rates of maturing as kittens we get to the figures above.
As an Amazon Associate I may earn a small fee from qualifying purchases at no extra cost to you. This helps us run the site, so thanks for your support!