Trying to determine a cat's age is one of the most difficult tasks, especially when they are adopted or rescued and appear adorable while not displaying ageing flaws like humans. Mr. Miyagi's true age was unknown to both foster parents and us when we adopted him. Of course, you can consult a veterinarian to help you determine your cat's age, but here are some quick tips for you.
Size
Size will be the most obvious indicator of your cat's age, whether it's a kitten, a young cat, or an adult cat. A cat living indoors has a life expectancy of about 17 years, and some even 20 years! Here's a chart of cat ages (for standard breed cats) to which we can refer as a starting point.
| Stage of Cat | Average Weight |
| Newborn | 100 - 170g |
| Below 5 weeks | 200 - 500g |
| 2 - 3 months | 700g - 2kg |
| 4 - 5 months | 2kg - 4kg |
| 6 months and adulthood | >4kg |
Eyes
Healthy kittens and cats have eyes that are very clear and bright, with no evidence of tearing or discharge. Cats in their senior years, on the other hand, may develop a cloudy appearance of their eyes, as well as tearing or discharge and usually occur at least 10 years old or more.
Hair
Cats, believe it or not, do get white or grey hair as they age, but usually not until they very old. Depending on the breed, your cat's hair may thicken or change color (darker or brighter) as they age. Cats are extremely clean creatures, but as they age, they may begin to slack off on grooming.
Teeth
The first baby teeth appear in kittens between the ages of 2 and 4 weeks. Their permanent teeth appear around 3 to 4 months of age, and they begin to displace the baby teeth (also known as deciduous teeth) around 6 months of age.
The amount of staining, or tartar, on a cat's teeth may be an indicator of age in older cats.
Maturity
Male cats can reach adulthood as early as 6 months of age. Territorial spraying and prominent urine testicles, if not neutered, are signs of puberty. Female cats typically have their first heat between the ages of 5 and 9 months, during which time they become extremely vocal.
Even with vets, we want to emphasize that any given age is only an educated guess. However, regardless of your cat's age, our role as cat parents is to keep them healthy and happy while they live with us.