How to Tell a Kitten's Age — Growth Stages & Development Guide

Knowing how to tell a kitten's age is one of the most useful skills for any cat parent — especially if you've rescued a kitten or taken in a litter without knowing their exact birth date. A kitten's age determines their nutritional needs, vaccination schedule, socialisation requirements, and developmental milestones. The two most reliable ways to estimate a kitten's age are physical development — including weight, eye opening, and mobility — and dental development. Here's your complete guide.

 

Birth: At birth kittens usually weigh between 80 – 100 grams

• New born 0 – 3 days: The umbilical cord is still attached, eyes are closed and ears are folded. Nose and paws may be pink in colour. The kitten is unable to see or hear
• 7 – 10 days: The eyes & ear canal begin to open
• 2 – 3 weeks: The kitten begins to stand, the eyes and ears open fully. Eyes will be baby blue and ears will appear small and rounded
• 4 weeks: The kitten begins playing and exploring its environment
• 5 weeks: The kitten should be fairly confident on its feet by this age

6+ weeks: Kittens are extremely active. The adult eye colour will begin to emerge

How to Tell a Kitten's Age by Their Teeth

 

Baby Teeth Timeline

• 2 weeks: Deciduous or milk incisors (the small teeth at the front) begin to come in
• 3 – 4 weeks: Deciduous or milk canines (the long, pointy teeth next to the front teeth – incisors) begin to come in
• 4 – 6 weeks: Deciduous or milk pre-molars (also known as bicuspids, these are the teeth located between the canine and molar teeth) begin to come in
• 8 weeks: All baby teeth have come in
  

Adult Teeth Timeline

• 12 – 16 weeks: Incisors come in
• 4 – 6 months: Canines, pre-molars & molars come in
• 7 months: All adult teeth should be fully developed 

Regardless of age, kittens benefit significantly from targeted nutritional support during their rapid early development. Venttura Amino+ Cat provides essential amino acids that support muscle growth, healthy development, and overall vitality in growing kittens. Venttura Immuno+ Cat strengthens immunity during the vulnerable early weeks when kittens are most susceptible to infections. Always consult your veterinarian about the appropriate age to begin supplementation for your kitten.

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These physical milestones give you a reliable estimate of your kitten's age during the first 6 weeks of life. After 6 weeks, dental development becomes the most accurate way to determine age — particularly the progression from baby teeth to adult teeth which follows a predictable timeline up to 7 months.

 

Frequently Asked Questions — How to Tell a Kitten's Age

 

Q1. How can I tell how old a kitten is without papers?

You can estimate a kitten's age accurately without documentation by observing their physical development and dental milestones. In the first few weeks, physical signs are most reliable — a kitten with their eyes still closed is under 10 days old, while one that is just beginning to stand and walk is around 2 to 3 weeks. By 4 weeks kittens begin playing and exploring, and by 6 weeks they are extremely active with adult eye colour beginning to emerge. For kittens older than 6 to 8 weeks, dental development becomes the most accurate indicator — baby incisors appear at 2 weeks, all baby teeth are present by 8 weeks, and the full set of adult teeth is complete by 7 months. If you are unsure, a veterinarian can provide a more precise age estimate through physical examination including weight, muscle development, and coat condition.

 

Q2. What does a 4 week old kitten look like?

A 4 week old kitten is at an exciting stage of development — they are fully mobile, beginning to play, and starting to explore their environment with confidence. Their eyes are fully open and will still be baby blue at this age — adult eye colour has not yet begun to emerge. Their ears are upright and responsive to sounds. Baby canine teeth are beginning to come in alongside the incisors that appeared around 2 to 3 weeks. At 4 weeks a kitten typically weighs between 350 and 450 grams and is starting to transition from solely mother's milk to solid food — a process called weaning that gradually completes over the next 2 to 4 weeks. They are still highly dependent on their mother or a human caregiver for warmth, feeding, and stimulation for elimination.

 

Q3. When do kittens open their eyes?

Kittens are born with their eyes sealed shut — a normal developmental state that protects their immature eyes from light and infection during the first days of life. The eyes begin to open gradually between 7 and 10 days of age, starting as a thin slit before opening fully over the following few days. By 2 to 3 weeks most kittens have fully open eyes — always baby blue at this stage regardless of what their adult eye colour will eventually be. Adult eye colour begins to emerge at around 6 weeks and fully develops between 3 and 6 months of age. Never attempt to force a kitten's eyes open before they are ready — the eyes will open naturally when the development is complete, and forcing them risks serious and permanent damage to the eyes.

 

Q4. At what age do kittens get their adult teeth?

Kittens go through two sets of teeth — baby teeth (deciduous teeth) and adult teeth — following a fairly predictable timeline. Baby teeth begin appearing at around 2 weeks with the incisors, followed by the canines at 3 to 4 weeks, and the pre-molars between 4 and 6 weeks. All baby teeth are present by 8 weeks. Adult teeth begin replacing baby teeth from around 12 to 16 weeks — starting with the incisors. Adult canines, pre-molars, and molars follow between 4 and 6 months. By 7 months all adult teeth should be fully developed and the kitten's permanent dental set is complete. Dental development is one of the most reliable ways to estimate a kitten's age — particularly between 2 weeks and 7 months when the teething timeline follows a consistent, well-documented progression.

 

Q5. How much should a kitten weigh at each stage of development?

Birth weight is the starting point — healthy newborn kittens typically weigh between 80 and 100 grams at birth. Kittens should gain approximately 10 to 15 grams per day during the first weeks of life — consistent weight gain is the most reliable indicator that a kitten is feeding adequately and developing normally. By 4 weeks a healthy kitten typically weighs 350 to 450 grams. By 8 weeks — when most kittens go to their new homes — they should weigh approximately 800 grams to 1 kilogram. At 3 months expect around 1.2 to 1.4 kilograms, and at 6 months between 2.5 and 3.5 kilograms depending on breed and sex. Kittens that fail to gain weight consistently or lose weight should be seen by a veterinarian promptly — poor weight gain in young kittens can indicate feeding problems, illness, or parasitic infection and requires immediate attention.

 

Conclusion

Determining a kitten's age accurately helps you provide the right nutrition, veterinary care, and socialisation at every stage of their development. Whether you're caring for a rescued newborn or a young kitten of unknown age, the physical and dental milestones in this guide give you a reliable framework. When in doubt, always consult your veterinarian — they can provide a more precise age estimate through physical examination.

 

Also read: How to Take Care of a Cat — Complete Guide for Pet Parents

Also read: Litter Training Your Kitten — Complete Guide