At most, a hen (female chicken) can lay one egg a day—but a hen will not always lay an egg every day. It takes 24 to 26 hours for a hen to produce an egg. See how a hen makes an egg.
The number of hours of light in a day stimulates a hen to start producing eggs. When the days start getting longer (that is, more hours of light each day) as happens in the spring and summer, it is a signal to a hen to start laying eggs. As the days start getting shorter (as happens with the fall and winter) the hen will stop laying eggs.
If you want to keep a hen laying eggs year-round it is important to give them a constant number of hours of light every day. This is usually 14 hours of light (and 10 hours of dark) each day. If your chickens are running around outside, you need to give them some extra light, either in the morning or at night (or a little of both) to make sure they are getting 14 hours of light every day. Otherwise they may stop laying eggs.
Dr. Jacquie Jacob
University of Kentucky