Kittens and cats who wind up in animal shelters or rescues very often have "hidden histories," meaning no one knows their background or age. Determining how old a feline family member is can be challenging — especially an adult. However, there are some things to look for that can help an adoptive pet parent or veterinarian make a reasonably educated guess at a kitty's age.
How to Gauge Your Cat's Age
• Body size — Healthy kittens under 6 months of age gain about a pound a month, so a 2-pound kitten is around 2 months old, a 3-pound kitten is 3 months old, and so on until about 6 months of age. After 6 months, it becomes difficult to gauge a cat's age by body size.
• Baby Teeth — A kitten's baby (deciduous) teeth start to appear at about 2 weeks, and finish erupting at around 8 weeks. Then at about 4 months, those teeth start to fall out, making way for the adult teeth. Most cats have all their adult teeth by about 7 months of age.
• Adult Teeth — In adult cats, the wear and tear on teeth, tartar buildup, and gum condition can provide clues as to their age. For example, if the teeth that run along the sides of the mouth show a minor amount of tartar, it's a safe bet kitty is in the 1-to-2-year range.
Generally speaking, the more tartar buildup on the teeth, the older the cat. However, there are kitties with "bad teeth" and those with teeth that don't accumulate much tartar, so this method of telling a cat's age is far from precise. And the same is true for gingivitis (gum inflammation), since some kitties develop severe gum disease very early in life.
• Eyes — At the start of middle age (around 6 to 7 years), the lenses of a cat's eye begin to get a bit cloudy. Initially, the cloudiness isn't visible except through an ophthalmoscope, but can become more noticeable to pet parents by the time the cat is 10.
In senior kitties, the normal aging process can cause the irises (the colored part of the eyes) to atrophy, with the result that the pupils appear larger than normal, or there's some waviness at the inner edge of the iris.
• Grooming — Cats take personal grooming very seriously, and the coats of younger kitties typically reflect their dedication to the task. Older cats, on the other hand, can lose some of their ability to keep their fur in pristine condition due to any number of things, including painful dental issues, weight gain that makes reaching the back half of their bodies more difficult, and arthritis.
• Health status — Just like older humans, aging cats are more likely than youngsters to develop health problems such as chronic kidney disease or hyperthyroidism.
It's important to keep in mind that even with knowledge of the above indicators, determining a cat's true age is a hit-or-miss proposition.
"We can look at the cat's eyes and teeth, do blood work and see how different organs are functioning, listen to the heart, and even measure muscle and fat, but unfortunately there isn't one specific attribute that allows us to say definitively that a cat is a certain age," Dr. Stephen Horvath, clinical assistant professor at the College of Veterinary Medicine at Ohio State University told PetMD. "It's really just making an educated guess."1
Five Stages of Kittenhood
Weeks 1 through 6 are the period during which kittens grow and develop very rapidly. Since they're all a little different, some may progress a bit more slowly, while others develop more quickly than average. There's no need for concern unless the rate of your kitten's development is significantly different from the norm.
• Stage 1: Newborn — Kittens weigh only a few ounces at birth, but they grow very fast, with most doubling their weight in the first week of life. During this time, the mother cat knows she must keep her babies warm, nourish them, and stimulate (lick) their bodies to encourage digestion and elimination.
Newborn kittens can't move around much, and the only noise they make is a faint mew. What remains of the umbilical cord typically drops off on day 2 or 3. They can neither see nor hear, since they're born with their eyes sealed shut and their ears folded. They're also toothless. At some point between days 5 and 14, kitty's little ears will start to unfold, and her eyes (always blue at first) begin to open.
• Stage 2: Two-week-old kitten — At 2 weeks, kittens begin to develop a sense of smell and their eyes open completely, though their vision is still blurry and sensitive to bright lights. At this stage, they become aware of their littermates and begin to compete for mom's nipples at mealtime.
• Stage 3: Three-week-old kitten — During his third week of life, kitty's sense of smell is fully established, and his ears become erect, though his hearing is still developing. He may start to get his little purr on, and baby teeth will begin to push up through his gums. His adult teeth will begin to replace them in a few months. Brief, gentle handling should begin at this point.
At this stage, mama cat no longer needs to stimulate her kittens to help them digest food or eliminate, but she does still have most of the grooming chores.
• Stage 4: Four-week-old kitten — At 4 weeks, kittens begin to interact with their littermates and show interest in their surroundings. They may attempt a few wobbly steps. By the end of the week, they're typically exploring and playing when they're not napping or nursing. This is exactly the right time to begin actively socializing her and getting her used to human handling.
• Stage 5: Five-week-old kitten — By 5 weeks of age, kitty's vision is fully developed, and her eye color may begin to change. She's growing more adventurous. Walking is less challenging and pouncing on littermates becomes great fun.
You can also introduce her to solid food this week, but she'll still need to nurse and isn't quite ready to be weaned. This is also a good time to introduce her to her litterbox. I recommend starting with a shallow box lid that she can easily step into and out of, with just a few inches of litter.
Your Cat's Age in Human Years
Like most animals, cats advance through kittenhood and the teen years much faster than humans. A 6-month-old cat is the equivalent of a 10-year-old child, and a 2-year-old kitty is about 24 in human years. At around 5 or 6, the pace slows down a bit, so a 10-year-old cat is approximately 56 in human years.
The following chart shows the life stages associated with feline ages and their approximate human equivalents:2
| Life Stage |
Cat Age |
Human Equivalent |
Kitten
(Birth to 6 months) | 0 – 1 month
2 – 3 months
4 months
6 months |
0 – 1 year
2 – 4 years
6 – 8 years
10 years |
Junior
(7 months to 2 years) | 7 months
12 months
18 months
2 years |
12 years
15 years
21 years
24 years |
Prime
(3 to 6 years) | 3
4
5
6 |
28
32
36
40 |
Mature
(7 to 10 years) | 7
8
9
10 |
44
48
52
56 |
Senior
(11 to 14 years) | 11
12
13
14 |
60
64
68
72 |
Super Senior
15+ years | 15
16
17
18
19
20
21 |
76
80
84
88
92
96
100 |
It's not uncommon for well cared-for cats to live into their late teens and early 20s these days. Unlike purebred dogs, the majority of kitties haven't been selectively bred, which dilutes the inherited traits that cause genetic disease. Indeed, most diseases seen in cats today are lifestyle-related, which means that as your kitty's guardian, you have a great deal of control over how well and how long she lives.
Consulting with a proactive, integrative veterinarian throughout your cat's life affords your pet the benefit of ongoing and dynamically changing wellness protocols at every phase her life. Supporting her physically, metabolically, nutritionally and immunologically as she ages is one the most important things you can do to not only extend lifespan but keep your cat's health exceptional as time goes on.