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How Long Does A Chicken Take To Grow?

Backyard Flock

It can be absolutely astounding how fast your fuzzy little chick will mature. They will come out of the box as helpless little fuzzballs and in just three weeks be partially feathered and rambunctiously fluttering around the brooder, testing your ability to contain them.

But while chickens do grow ridiculously fast, not every breed matures at the same pace. Depending on their purpose, a chicken will be done growing anywhere from 7 weeks to 18 months of age. This wide range is the result of deliberate breeding practices, so it pays to do your homework when starting a flock.

For example, Broilers are a type of chicken that are considered ‘fast-growing’. A considerable amount of effort has been spent with the goal of producing a breed chicken that yields the largest amount of meat in the shortest amount of time. This can be seen in the Cornish Cross Chicken, which is generally ready for butcher, starting at around 7 weeks of age.

In comparison, the Jersey Giant Chicken is a breed that is actually larger and heavier than most broilers. But this chicken is considered a ‘slow-growing’ breed as it will not be finished growing until roughly 18 months of age. For this reason, most people who are looking to capitalize on meat production will go with a fast-growing breed rather than the Jersey Giant.

If however, your goal is to have eggs, then you can generally expect your hens to start laying at around six months of age.

It should be noted, though, that your chick will be fully feathered and looking very much like an adult chicken long before that; at around 8 weeks of age.

Their combs and wattles will take longer to develop. And there will be quite a bit of ‘filling in’ to do, with regards to both weight and height. Their tail feathers will probably still be a little lacking, but the majority of their development in appearance will be done. Most importantly, their ability to maintain proper body temperature will be achieved – meaning they should be ready to graduate from the brooder into the adult coop.

Chicken Development Timeline

When you get your chicks home for the first time, things can be a little overwhelming. There is just so much that has to be ‘just right’ in order for your birds to be the happy healthy chickens that you want them to be. And while it can be very daunting to someone raising a flock for the first time, it’s worth knowing that the high degree of care will lessen to a much more manageable level in a very short time.

The following is a brief description of each phase of the typical backyard egg-laying chicken’s life.

  • The Cloaca Kiss – This is the process where the eggs are fertilized. The rooster and hen have done their thing and the exciting potential for offspring begins. For an in-depth look at this, check out, ‘How Do Chickens Mate?
  • Broody Behavior – When a hen goes broody, she will begin the process of preparing for chicks. This begins with her sitting on a nest for long periods of time as she sets about collecting enough eggs. Once her clutch of eggs is of adequate number, she will move onto the next phase of the process. ### Important Note ###
    • Incubation – This is where your hen will keep the eggs at a very critical temperature in order for proper development. And while it may look the same as being broody, it is notably different. This is because all of the eggs should hatch on the same day. And as hens will only lay one egg a day, then it will take nearly 2 weeks for there to be enough eggs to have a clutch. With incubation for developing chicks being 21 days, then you can understand why it is so critical for the hen to wait until every egg is in the nest. If she was to begin incubation with the very first egg, then none of the other eggs would hatch as she will abandon the nest to care for the hungry chick that has just arrived.
    • Fully Feathered – When a chick emerges from its shell, it will be predominately covered with down. And while this particular type of feather is ‘uber soft’, it is not enough for them to regulate body temperature. Consequently, without an adequate source of heat, the chick will perish.

    However, their feathers will come on fast. Generally, by 8 weeks of age, a chicken will have enough feathering by as to maintain their own body heat.

    • Reproductive Capable – A species is usually considered an adult when it has developed the physical maturity necessary to reproduce. Should you desire a flock with both hens and roosters, then you should be aware of the fact that this maturity will happen at different times.

    For roosters, the drive to mate begins at around 4 months of age.

    For hens, the drive to mate begins at around 6 months of age.

    This is very critical to understand!

    Should you get a batch of chicks with a rooster in it, then be prepared to separate him as he will want to act before the girls are capable of understanding the situation. They will see his behavior as an attack. And a rooster thwarted can become more and more aggressive. It is not unusual for a rooster to cause significant injury to a hen.

    So to recap, until your hen has realized her reproductive maturity, she will not be capable of understanding the situation, let alone respond to it. Her safety will depend entirely upon your intervention, as a rooster is generally larger than a hen, and will never stop.

    • Full Size – While it is easy to think of your egg laying birds as adults, most breeds will continue to grow. This growth will be slower than what you have seen for the first 6 months, however, they will continue to ‘bulk up’ until roughly 12 months old. (The bigger Jersey Giant growing all the way up to 18 months).

    And it’s not just girth that continues to develop. Combs and wattles will grow bigger and, in the case of roosters, spurs will continue to extend. However, at the end of 12 months, your chicken should have achieved its maximum growth potential.


    I can tell you from personal experience that raising chickens can be incredibly rewarding. If you are considering raising a small flock – even just 3 birds – then it would be to you and your flock’s benefit to do a little homework.

    Once a chicken hits eight weeks old, then life gets a lot easier. But those first two months have unique demands and if you aren’t properly prepared for them, you flock will suffer for it. To learn more about this, check out, ‘Raising Chickens: Five Easy Steps For The 1st Timer.