How to Tell a Kitten's Age: Weight, Eyes, Teeth and Behavior Clues

By Tailwisp Editorial TeamUpdated October 20, 20264 min read

If you find a kitten, or have just adopted one without papers, you may need to work out how old it is. Age decides how often to feed, what to feed, when to vaccinate and how to care for it. Fortunately, kittens develop quickly and in a fairly predictable order.

Quick age guide

Weight

In the first weeks, kittens gain about half an ounce to an ounce per day, and a common rule of thumb is that weight in ounces roughly matches age in weeks for the first few weeks. After that, many kittens weigh about a pound for each month of age up to six months. Breeds, litter size and nutrition affect weight, so use it only as one clue. Weigh with a kitchen scale. See kitten growth and development week by week.

Eyes

• Newborn: closed.
• 7 to 10 days: begin to open, blue.
• 2 to 3 weeks: fully open, but vision is still limited.
• 6 to 8 weeks: color begins to change, and adult color may take up to three months.

Eye discharge needs attention. See cat eye problems.

Ears

Newborn ears are folded and flat. They begin to unfold at around one to two weeks and stand upright by three to four weeks. Ear canals are open at about two weeks.

Teeth

Teeth are one of the best clues.

• 2 to 3 weeks: incisors appear.
• 3 to 4 weeks: canines come in.
• 5 to 6 weeks: premolars appear, completing 26 baby teeth.
• 3 to 4 months: adult incisors begin to replace baby teeth.
• 6 to 7 months: all 30 adult teeth are in.

See kitten teething.

Mobility and behavior

• Under two weeks: crawls, and cannot regulate temperature.
• 3 weeks: stands and walks unsteadily.
• 4 weeks: walks, starts play, uses a litter box. See kitten litter training.
• 5 to 7 weeks: runs, pounces, grooms.
• 8 weeks and up: confident and playful. See how to play with a kitten.

Umbilical cord and other signs

A newborn may still have a dried cord stump, which falls off within a few days. Very young kittens cannot pee or poop without stimulation from their mother. If you find such a kitten, see what to do if you find a stray kitten and how to bottle feed a kitten.

Why age matters

• Feeding. Under four weeks needs milk replacer. See kitten feeding schedule and how to wean kittens.
• Vaccines. Start at six to eight weeks. See cat vaccination schedule.
• Spay or neuter timing. See when to spay or neuter a kitten.
• Temperature and care. Very young kittens need warmth.

When to see a vet

A vet can examine teeth, size and development, and give a better estimate. Book a visit soon after you find or adopt a kitten. See kitten first vet visit. Use the US vet directory to find a clinic.

Using more than one clue

No single sign gives a reliable age, so combine them. A kitten with open eyes, folded ears, no teeth and a weight of about eight ounces is probably around two weeks old. A kitten with upright ears, a full set of baby teeth, steady walking and a weight near one and a half pounds is probably six to seven weeks. Photograph the kitten with a coin or ruler each week to keep track of growth.

Differences between breeds and litters

Large breeds such as the Maine Coon grow more slowly and may weigh more at the same age. Kittens in large litters can be smaller. Runts may lag behind their littermates. See Maine Coon for an example of a slower-maturing breed.

Health and growth

If a kitten is not gaining weight, or seems small for its estimated age, a vet should check it. Parasites, infections and poor nutrition all slow growth. See worms in cats.

Limits of estimation

Underfed or sick kittens may be smaller than their age, and breed differences matter. Treat any age estimate as a range, and keep it updated as the kitten grows.