How To Tell How Old a Kitten Is

Photo of Karen Dell

Karen Dell

Senior Editor • Backyard Cat Enclosures

09 April 2019

While knowing how old kittens are is easy when it’s your cat who’s given birth, it may not be as easy as pie to know how old kittens are otherwise because they grow extremely fast during their first weeks.  
Here’s a quick guide to show how kittens change and mature over the first 12 months of their lives.
First few days:
  • Weighs only a few ounces
  • Umbilical cord still attached
  • Eyes and ear canals are closed
  • They must be bathed to help them digest milk, urinate, and defecate
Week 1:
  • Still weights only about 3.5 ounces on average
  • After two or three days the umbilical cord falls off
  • Their eyes and ear canals are still closed
  • Mother bathes them to help digest milk, urinate, and defecate
  • At this time they feed about every two hours
Week 2:
  • Kittens put on weight at almost 10g per day
  • Between days nine and fourteen their eyes will completely open
  • The kitten’s senses intensifies
  • They must still be washed by their mother
  • They cannot yet voluntarily urinate and defecate
  • Their baby teeth may start to show
Week 3:
  • The kittens will become more aware of their surroundings
  • Their ear canals open completely and their ears are now fully erect
  • Their blue eye colour may change (to the colour eyes they’ll have as an adult)
  • They still need to be washed by their mother
  • They can now urinate and defecate on their own
  • They can start to purr
  • Their baby teeth will start to show
Week 4:
  • By their fourth week of life, kittens will start walking around
  • They will still get all their sustenance from nursing  
Week 5:
  • During week five a kitten will start to wean, but will still be very reliant on their mother’s milk (or a milk replacement, if they have been orphaned) It is during this week that kittens should be introduced to canned food
  • It’s also time to keep litter boxes handy at this time, as the kittens will be using them now
  • The kittens in the litter will be socialising with one another more than before
  • They are also ready to start socialising with humans at this age (unless they have been hand raised)
  • They are still too young to go to new owners at this age
Week 6-8:
  • The kittens will continue to socialise more with their litter mates and should ideally be socialised with humans at this time if it hasn’t started yet
  • The kittens may be playful and full of energy, but they are still weaning and still need both milk and solid food
  • Between weeks 6 and 8, the kitten will receive its first vaccination against the three major diseases (feline herpes virus (”cat flu”), feline calicivirus, feline panleukopaenia (also called feline distemper)
  • Kittens can get desexed (spayed or neutered) as early as 8 weeks — usually as soon as safely possible in a shelter environment.
Week 10:
  • By  week 10 kittens are completely weaned from drinking milk and can be re-homed to their new parents
  • Note that kittens should not be given cow’s milk to drink as they no longer need to drink milk (and cow’s milk is bad for them in any case)
  • Between week 10 and 12 a booster vaccination is given to kittens
Week 12:
  • Still in the window during which kittens are usually re-homed
  • They have already received some vaccinations, but still need follow-up ones
  • They start losing their baby teeth, which gets replaced by their permanent teeth — time to start brushing those pearly whites!
Week 14-16 (approximately 4 months old):
  • During this time the final vaccination is given, including the vaccination against Feline AIDS. (ten days after this vaccination you can let your kitten go outside, preferably to play safely within their enclosure)
Month 6:
  • When kittens reach the age of 6 months, they will look like a little adult already, although they still have some growing to do before they reach their adult size
  • They will weigh about 6 pounds, depending on their breed size as kittens usually gain about one pound of weight a month
  • Kittens can reach sexual maturity at six months, so if you have not yet spayed or neutered your kitten(s), now is the time
  • A few baby teeth may still be present.
Month 7-8:
  • Your kitten will start to sleep more, just like adult cats do, for usually more than half the day
  • Kittens, if socialised from a young age, will most likely now snuggle with you on their own
  • You’ll need to set boundaries with your kitten now to teach them, for instance, not to bite and scratch. Use positive reinforcement instead of scolding them
Month 9:
  • The kitten’s adult teeth are now fully formed
  • Continue training your kitten using little treats and positive reinforcement
Month 10:
  • By month ten you can start to transition your kitten to adult cat food. Make sure this is a slow transition, though, over at least a week to decrease the likelihood of dietary-unduced diarrhoea
Month 12:
  • The transition from kitten to cat is complete!
  • Most cats are fully grown by 12 months, although there are some breeds that keep on growing for a while longer

Photo by Zetong Li on Unsplash


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