Eggs take 21 days to hatch into baby chicks. During each day in the embryo stage, chicks show distinct changes in development. By day 20, the chick should start trying to break its way through the shell. However, it’s possible for chicks to hatch a little bit early or late.

Chicken eggs take 21 days to hatch. An incubator must be monitored diligently; chicks left too long after hatching will die of dehydration or pecking. On the whole, we find it best to leave hatching to the hen.

First things first—chicken eggs should hatch in 21 days, though some may hatch a day or two early and some a day or two late after the incubation period began. A "day" is counted as a full 24 hours, so day one would be the first 24 hours after setting the egg. Day two the next 24 hours, etc.

Usually, if temperature and humidity levels have been ideal, the hatchling will start to break through the shell 21 days after the eggs were first set. However, this is very much a "rule of thumb". Sometimes it takes longer and sometimes shorter times.