How long do chickens lay eggs for?

The hen breeds used in commercial egg farming start laying eggs at around 16-18 weeks (four months) old. The first eggs laid by hens at this young age are relatively small at about 45-50 grams. But over a period of about three months, the egg size increases to an average of 60 grams. Commercial laying hens continue to produce first quality eggs until they are about one and a half years old. After this, their eggs become fewer and shell quality decreases which leads to more cracking and breaking.