When will my chicken be full-grown?

[Alex S]

My chickens are 5 weeks old and are getting pretty big! But I was wondering when there supposed to be full grown. Also when do Buff Orpingtons usually start laying eggs?

 

[Matejka]

1 year is full grown. They should reach good size by 6 months, and be fully feathered and go out to coop (away from brooder) around 10-12 weeks) but are still considered pullets/cockerels til a year.
They can start laying anywhere from 20 weeks to a year.
My started laying around 25 weeks (a little over 6 months old).

 

[CHlCKEN]

Fully feathered at 6 weeks old, Begin laying at 18-30 weeks, and should be fully grown around 24.