Most chickens reach sexual maturity between 18 and 24 weeks of age, though the exact timing depends on breed, diet, and daylight exposure. Pullets (young females) typically lay their first egg around 18 to 20 weeks, while cockerels (young males) can become fertile as early as 16 weeks.
The Growth Phases Leading to Maturity
Chickens go through a rapid grower phase from about 7 to 18 weeks of age. During this stretch, their digestive systems, immune systems, and bones are still developing. Sexual differentiation becomes visible between 7 and 16 weeks, when combs and wattles start growing at noticeably different rates in males versus females. By the end of this phase, a pullet’s body is preparing to produce eggs and a cockerel is developing the physical traits needed for breeding.
The transition from “grower” to “mature bird” isn’t a single moment. It’s a gradual process where hormonal changes drive visible physical and behavioral shifts over several weeks.
When Pullets Start Laying
Production-type breeds, like Leghorns and commercial hybrids, tend to lay their first egg between 18 and 20 weeks. Heritage and dual-purpose breeds often take longer, with some not laying until 22 to 26 weeks. Bantam breeds vary widely. Early-maturing pullets generally produce more eggs over their lifetime and stay productive longer than late starters.
You can begin watching for signs of readiness around weeks 16 to 17. This is also the time to start transitioning from grower feed to a layer feed with higher calcium content to support eggshell production. Make the switch gradually once birds hit 18 weeks or when the first egg appears, whichever comes first.
The earliest eggs, called pullet eggs, are small and sometimes oddly shaped. Egg size increases steadily over the first few months of laying as the reproductive tract fully matures.
When Roosters Become Fertile
Cockerels often start attempting to mount hens as young as 8 to 12 weeks, but they aren’t actually fertile at that age. True fertility typically begins around 16 weeks in some individuals, though many roosters don’t reach reliable breeding capability until closer to 5 or 6 months. Interestingly, young roosters can become fertile several weeks before their sisters start laying. This gap is normal and doesn’t indicate a problem with the pullets.
Crowing usually begins well before full maturity. Some cockerels start practicing rough, broken crows as early as 8 to 10 weeks, with a full, consistent crow developing over the following months.
Physical Signs of Maturity in Hens
Several visible changes signal that a pullet is approaching laying age. The comb and wattles grow larger, turn from pale pink to a rich, bright red, and become soft and waxy to the touch. A dull, shrunken, or pale comb generally means a hen is not yet laying or has stopped.
The pelvic bones also change. In a mature, actively laying hen, the two pubic bones (felt just below the vent) should be thin, flexible, and spaced more than two finger-widths apart. A wider gap, around three fingers between the pubic bones and four fingers between the pubic bones and the tip of the keel (breastbone), indicates excellent abdominal capacity for egg production. A hen with only one finger-width between the pubic bones is either immature or a poor layer.
Behavioral Cues to Watch For
One of the most reliable behavioral signs is the submissive squat. When you reach toward a pullet and she crouches low, spreads her wings slightly, and holds still, she’s displaying a mating posture that signals sexual maturity. Some pullets begin squatting as early as 14 weeks, though it more commonly appears closer to 18 weeks.
You may also notice pullets investigating nesting boxes with new curiosity, sitting in them without producing an egg at first. A whining or restless vocalization sometimes precedes the first lay. Once a hen starts producing eggs, she’ll often announce it with a distinctive, repeated call known as the egg song, typically accompanied by a proud, strutting walk around the coop. This vocalization also plays a role in establishing pecking order within the flock.
How Daylight Affects the Timeline
Light exposure is one of the biggest environmental factors controlling when chickens mature. Pullets raised under short daylight conditions of 10 hours or less actually reach maturity faster once they’re exposed to longer days. This seems counterintuitive, but short days during the growing phase help reset a natural hormonal mechanism called photorefractoriness, essentially priming the bird’s reproductive system to respond strongly when day length increases.
Pullets raised under long daylight of 13 hours or more during their growing phase can experience delayed maturity and lower overall egg production. This is why commercial operations carefully control lighting schedules, often raising pullets on 8 to 10 hours of light, then increasing to 16 hours around 21 weeks to stimulate the onset of lay. For backyard flocks, this means chicks hatched in late summer or fall (when days are getting shorter) often mature and begin laying on a predictable schedule once spring daylight returns. Chicks hatched in spring under naturally long days may take slightly longer to start.
Breed Differences in Maturity
Not all chickens mature on the same schedule. Lightweight, egg-production breeds like Leghorns and Red Sex Links are among the fastest to mature, often laying by 17 to 18 weeks. Medium-weight dual-purpose breeds like Plymouth Rocks, Orpingtons, and Wyandottes typically start between 20 and 24 weeks. Larger, heavier breeds like Cochins and Brahmas are known for being late bloomers, sometimes not laying until 28 weeks or later. Their roosters follow a similar pattern, reaching full fertility around 6 months.
If you’re raising a mixed flock, expect the lighter breeds to start laying weeks before the heavier ones. This staggered timeline is completely normal and not a reason to adjust feeding or lighting for individual birds.
Nutrition During the Transition
What you feed during the grower phase directly affects how well a pullet’s body prepares for egg production. Grower feed, with moderate protein and low calcium, supports bone and muscle development from about 7 to 18 weeks. Switching to layer feed too early can cause problems because the high calcium content (needed for eggshells) can damage the kidneys of birds that aren’t yet laying.
The ideal transition window is around 18 weeks or at the first egg. Mix the new layer feed gradually with the remaining grower feed over about a week. If you have a mixed-age flock where some birds are laying and others aren’t yet, an all-flock feed with a separate dish of oyster shell lets the laying hens self-supplement calcium without forcing it on younger birds.