# When Do Chickens Start Laying Eggs? Age Chart
Most hybrid laying breeds produce their first egg between 18 and 22 weeks of age. Heritage breeds and heavier dual-purpose birds usually start later, commonly 24 to 30 weeks, and some individuals hold out past 32 weeks. The single biggest driver of that spread is genetics, followed by body weight at point of lay, nutrition during rearing, and how much daylight the pullet experiences as she approaches sexual maturity.
This article explains the biology behind the first egg, gives a breed-by-breed age chart with typical mature body weights and expected egg sizes, and covers the management factors that pull the first egg earlier or push it later. It is written for backyard keepers who want a realistic timeline instead of a marketing promise.
This article is educational and is not a substitute for veterinary diagnosis or treatment.
## The Direct Answer, With Realistic Ranges
A pullet does not "decide" to lay. Her reproductive tract matures on a schedule set by genetics and modulated by environment. Age at first egg (AFE) is a measurable, heritable trait, and researchers use it constantly as a selection criterion in layer breeding programs [1][2][3]. That means the number you see for a breed is a population average, not a guarantee for the individual bird in your coop.
Practical ranges for backyard flocks:
- Commercial hybrid layers (sex-linked brown egg hybrids, White Leghorn-type hybrids): 18 to 22 weeks.
- Fast-maturing heritage and dual-purpose breeds: 20 to 24 weeks.
- Slow-maturing heritage breeds and heavy dual-purpose breeds: 24 to 30 weeks.
- Large fowl and ornamental breeds with low selection pressure for egg production: 28 to 36 weeks, sometimes later.
Two studies make the genetics concrete. A long-term selection experiment on Taiwan indigenous chickens tracked AFE across 18 generations and found heritability estimates for AFE ranging from 0.09 to 0.61 depending on line and generation stage [1]. In a genome-wide association study of Wuhua yellow chickens, SNP-based heritability for AFE ranged from 0.10 to 0.38, and AFE showed negative genetic correlations with egg number and clutch traits [4]. Translation for the keeper: how early a hen starts is partly written into her DNA, and the breeds selected hardest for early maturity start earliest.
A study comparing Lohmann Selected Leghorn hens with two low-performing genotypes (Junglefowl phenotype and Sumatra) recorded the first egg in the 18th week for the Leghorn-type birds versus the 24th week for Junglefowl-phenotype birds and the 31st week for Sumatra hens [5]. That is a clean illustration of the same principle in a single controlled comparison.
## Breed-by-Breed Age Chart
The table below gives typical first-egg ages, mature body weights, and expected egg sizes for common backyard breeds and categories. Egg size at the very first egg is almost always small. A pullet's first eggs often weigh 40 to 45 g, and egg weight climbs over the first several weeks of lay. In one genetic study of three Tanzanian ecotypes, mean egg weight was 43.1 g [6]. Expect the first month of eggs to be noticeably smaller than the breed's mature egg size.
| Breed or category | Typical first egg (weeks) | Mature hen body weight | Mature egg size |
|--|--|--|--|
| Commercial sex-linked brown hybrids (ISA Brown, Golden Comet, Red Star) | 18 to 22 | 5.5 to 6.5 lb (2.5 to 3.0 kg) | Large to extra large |
| White Leghorn and Leghorn-type hybrids | 18 to 22 | 4.5 to 5.5 lb (2.0 to 2.5 kg) | Large to extra large |
| Australorp | 20 to 24 | 6.5 to 8.0 lb (3.0 to 3.6 kg) | Large to extra large |
| Rhode Island Red | 20 to 24 | 6.5 to 7.5 lb (3.0 to 3.4 kg) | Large to extra large |
| Plymouth Rock (Barred, White) | 22 to 26 | 7.0 to 8.5 lb (3.2 to 3.9 kg) | Large |
| Orpington | 24 to 28 | 7.0 to 8.5 lb (3.2 to 3.9 kg) | Large |
| Wyandotte | 22 to 26 | 6.0 to 7.5 lb (2.7 to 3.4 kg) | Large |
| Sussex | 22 to 26 | 6.5 to 8.0 lb (3.0 to 3.6 kg) | Large |
| Brahma | 26 to 32 | 8.5 to 10.0 lb (3.9 to 4.5 kg) | Large to extra large |
| Cochin | 28 to 34 | 8.0 to 10.0 lb (3.6 to 4.5 kg) | Medium to large |
| Silkie | 24 to 30 | 2.5 to 3.5 lb (1.1 to 1.6 kg) | Small to medium |
| Easter Egger | 20 to 26 | 5.0 to 6.5 lb (2.3 to 3.0 kg) | Medium to large |
| Marans | 22 to 28 | 6.5 to 8.0 lb (3.0 to 3.6 kg) | Large to extra large |
| Ameraucana | 22 to 28 | 5.5 to 6.5 lb (2.5 to 3.0 kg) | Medium to large |
| Heritage turkey-type body builds and slow-growing natives | 26 to 36+ | Varies widely | Small to medium |
Body weights in the table are typical breed-standard ranges for mature hens. Use them as a target, not a rule. The weight that matters most is the pullet's weight at the point of lay, discussed below.
## The Biology Behind the First Egg
The hen's ovary and oviduct: the reproductive anatomy that must mature before the first egg can be laid. Image: Apperson, K.D.; Bird, K.E.; Cherian, G.; Löhr, C.V., CC BY 4.0, via Wikimedia Commons.
A hen's egg-laying system is a two-part machine: a light-sensing hormonal switch and a physical assembly line.
### How light triggers the reproductive axis
Chickens detect day length through the pineal gland and the hypothalamus. When day length increases, the hypothalamus signals the pituitary to release gonadotropins, which drive ovarian follicular development. In practical terms, a pullet needs to experience increasing day length to switch on reproduction. Photostimulation studies make this measurable. In a White Leghorn breeder study, pullets photostimulated at 18 weeks showed sharp increases in ovary weight, number of large yellow follicles, oviduct weight, and oviduct length within weeks of the light change [7]. A parallel study in Beijing-You chickens found that birds photostimulated at 22 weeks had ovary and oviduct weights 8.68-fold and 4.27-fold higher than birds photostimulated at 16 weeks, measured six weeks after the light change [8].
The target for backyard flocks is a total day length of about 14 to 16 hours of light to trigger and sustain reproductive development. Natural day length does this in spring and early summer. If your pullets reach laying age in fall or winter, shortening days will delay the first egg, sometimes by months, because the hormonal signal to mature the ovary is absent or declining.
### Why body weight at point of lay matters
A pullet has to be big enough to lay. Body weight at point of lay is one of the strongest nongenetic predictors of when she starts and how well she lays afterward. A classic study by Summers and Leeson fed White Leghorn pullets diets containing 20, 17, 14, or 11 percent protein from hatch to 16 weeks. Birds on the 14 and 11 percent protein diets were 11 and 27 percent lighter at 16 weeks than the 20 percent group, came into production slightly later, and laid smaller eggs for much of the laying cycle. The authors concluded the smaller eggs were most likely because the underfed pullets had smaller body weights, not because of a specific protein reserve effect [9].
The takeaway is direct. A pullet that is underweight at the point of lay will usually start later and lay smaller eggs at first. Rearing nutrition that supports steady growth, adequate protein, and appropriate calcium during the pre-lay period sets the stage for an on-time first egg.
### The role of calcium
Calcium is the raw material for eggshell. A pullet's skeleton is still mineralizing when she approaches lay, and she draws on medullary bone reserves to build shells. In the keel bone study comparing Lohmann Selected Leghorn hens with low-performing genotypes, keel bone ossification was completed significantly later in the slow-maturing Sumatra hens [5]. That study focused on keel bone health rather than egg timing, so treat it as context, not proof. The practical point stands: a pullet needs adequate dietary calcium before and during the transition to lay, and a pre-lay or transition diet is standard practice in commercial and backyard flocks.
## What Advances the First Egg
Three things reliably move the first egg earlier.
**Genetic potential.** Breeds selected for early maturity start earliest. The Leghorn-type versus Sumatra comparison (18 weeks versus 31 weeks) is the clearest example in the literature [5]. AFE is heritable, with estimates ranging from 0.09 to 0.61 in one long-term selection study [1] and 0.10 to 0.38 in a Wuhua yellow chicken population [4].
**Adequate body weight at point of lay.** Pullets that hit their target weight on schedule come into lay on schedule. Pullets that are behind on weight come into lay late [9].
**Increasing day length.** Photostimulation at the right age advances sexual maturity. In the White Leghorn breeder study, photostimulation at 18 weeks produced the sharpest early reproductive development, while photostimulation at 16 weeks delayed the rise to 5 percent production by 28 days and photostimulation at 22 weeks reduced peak production [7]. The Beijing-You study found that photostimulation at 16 weeks produced an earlier age at 5 percent production than photostimulation at 20 or 22 weeks, but later photostimulation produced heavier eggs [8]. The pattern across both studies is that very early photostimulation is not automatically better.
For backyard keepers, the practical version is simple. If pullets reach 18 to 20 weeks in spring or summer, natural lengthening days support an on-time start. If they reach that age in fall, adding supplemental light to reach 14 to 16 hours total can keep the process moving.
## What Delays the First Egg
**Decreasing daylight.** This is the most common cause of a "late" pullet in a backyard flock. A pullet that reaches 20 weeks in October, when days are getting shorter, may not lay until the following February or March. The reproductive axis responds to increasing photoperiod, and a declining photoperiod is the wrong signal.
**Underweight pullets.** Protein-restricted rearing diets produced 11 to 27 percent lighter pullets at 16 weeks, and those birds came into production slightly later [9]. Severe underweight can delay lay by weeks.
**Cold and heat stress.** Extreme temperatures divert energy away from reproduction. The broiler breeder study by Leksrisompong and colleagues noted that a fast feed-increase program raised body weight at 31 weeks and was associated with increased female mortality during summer weather in early lay [10]. That study was about broiler breeders, not backyard layers, but the underlying physiology (heat stress and early-lay metabolic load) applies broadly.
**Disease.** Clinical disease pauses or delays lay. An avian reovirus study in laying hens found that infected hens maintained normal egg production with only minimal signs, but that study deliberately used a mild challenge in healthy commercial birds [11]. Field disease with systemic illness, respiratory signs, or reproductive tract involvement is a different situation and commonly disrupts laying.
**Molt.** A hen in molt stops laying while she replaces feathers. Molt is normal and seasonal, and it is a pause, not a permanent stop.
**Stress and management disruption.** Moving, predator disturbance, crowding, and abrupt feed changes can all interrupt or delay the onset of lay.
## The First Egg Is Not the Peak
A pullet's first egg is the start of a curve, not the top of it. Egg production climbs over several weeks to a peak, and egg size climbs with it. The White Leghorn breeder study recorded peak egg production at 183 to 218 days depending on photostimulation age [8]. The Beijing-You study found later peak production in the later-photostimulated groups [8].
Two practical implications. First, expect small eggs for the first few weeks. In the Tanzanian ecotype study, mean egg weight was 43.1 g across the production period, with the heaviest eggs appearing in the fifth 90-day period [6]. Second, do not judge a pullet's productivity by her first month. Judge it by her output over the first 40 to 60 weeks.
There is also a documented trade-off between early maturity and long-term performance. A study of Beijing-You and White Leghorn purebreds and crossbreds found that extremely early-maturing hens showed initial production advantages that diminished at later stages, and that the genetic correlation between AFE and cumulative egg number to 100 weeks was positive in the combined population [2]. In other words, the earliest starter is not automatically the best long-term layer. For a backyard flock, that is a reason to value steady, well-grown pullets over the earliest possible first egg.
## Practical Management for an On-Time First Egg
1. **Know your breed's realistic window.** Use the chart above. A Brahma at 26 weeks is normal. A Brahma at 20 weeks would be unusual.
2. **Weigh your pullets.** Track body weight against the breed standard from about 12 weeks onward. If they are behind, adjust the ration rather than waiting.
3. **Feed a proper rearing diet.** Adequate protein during growth supports body weight at point of lay, which in turn supports on-time lay and normal egg size [9].
4. **Plan the hatch date around the calendar.** A pullet hatched in early spring will reach laying age in summer, when natural day length is long and increasing. A pullet hatched in late summer will reach laying age in late fall or winter, when day length is short and decreasing. That single decision changes the timing of the first egg more than any supplement.
5. **Use supplemental light deliberately.** Target 14 to 16 hours of total light per day. Add light in the morning rather than the evening so the flock's natural dusk behavior is not disrupted.
6. **Do not photostimulate too early.** The breeder studies found that photostimulation at 16 weeks delayed the rise to 5 percent production and increased broken and abnormal eggs in White Leghorns [7]. Wait until pullets are close to their target weight and at least 18 weeks old.
7. **Provide adequate calcium before lay.** Transition to a pre-lay or layer ration as the first egg approaches.
8. **Keep stress low.** Stable housing, consistent feeding times, and protection from predators all support uninterrupted onset of lay.
## Common Myths and Misconceptions
**Myth: All chickens start laying at 18 weeks.** Only the fastest hybrid layers reliably do. Heritage and heavy breeds commonly start at 24 to 30 weeks, and the Sumatra comparison in the keel bone study started at 31 weeks [5].
**Myth: A late pullet is a broken pullet.** A pullet that reaches laying age in shortening daylight is behaving normally. She is waiting for the right photoperiod signal.
**Myth: You can force a pullet to lay early with supplements.** The evidence points to genetics, body weight, and photoperiod as the controlling factors. No supplement substitutes for those.
**Myth: The first egg tells you how good a layer she will be.** Early maturity and long-term egg number have a complex relationship. In one study, extremely early-maturing hens lost their initial advantage at later stages [2].
**Myth: A hen that stops laying is done forever.** Molt, cold, stress, and disease all pause lay. Many hens resume after the trigger passes.
## Limitations and When to Contact a Veterinarian
Individual birds vary, and a breed average cannot tell you what a specific pullet will do. If your pullet is past the upper end of her breed's normal range and shows no signs of approaching lay (no reddening and enlargement of the comb and wattles, no squatting behavior, no interest in nest boxes), a veterinary examination is reasonable.
Contact a veterinarian promptly if you see any of the following:
- A pullet or hen with a distended, fluid-filled, or hard abdomen.
- Straining, prolapse, or a visibly stuck egg.
- Sudden drop in feed or water intake across the flock.
- Respiratory signs, diarrhea, or unexplained deaths in the flock.
- A hen that stops laying and also loses weight, has a pale comb, or appears depressed.
- Any bird that has not laid by roughly 36 weeks despite normal body weight and adequate light.
According to the AVMA, backyard poultry owners should work with a veterinarian on flock health and biosecurity, and many state veterinary diagnostic laboratories offer poultry necropsy and disease testing services. A veterinarian familiar with poultry can assess body condition, reproductive tract health, and whether a delay in lay is management-related or medical.
## Frequently Asked Questions
### At what age do most chickens start laying eggs?
Most hybrid layers start at 18 to 22 weeks. Heritage and heavy breeds typically start at 24 to 30 weeks, and some slow-maturing breeds start later than 30 weeks.
### Why is my 24-week-old hen not laying yet?
The most common reasons are breed genetics, short or decreasing day length, and low body weight at point of lay. A pullet reaching 24 weeks in fall or winter may wait until spring.
### Does light really control when a chicken starts laying?
Yes. Increasing day length triggers the hormonal cascade that matures the ovary and oviduct. A target of 14 to 16 hours of total light per day supports the onset of lay.
### Can I make my pullets start laying earlier?
You can support an on-time start by keeping pullets at target body weight, feeding an adequate rearing ration, and providing 14 to 16 hours of light once they are at least 18 weeks old. You cannot override genetics.
### Do hens lay smaller eggs at first?
Yes. First eggs are usually small, often 40 to 45 g, and egg size increases over the first several weeks of lay.
### What happens if my pullet starts laying in winter?
She may lay, but cold stress and short days can reduce output. Provide adequate light and shelter, and expect a slower start than a spring-maturing pullet.
### Can stress or illness stop a hen from laying?
Yes. Molt, cold, heat, moving, predator disturbance, and disease can all pause or delay lay. Most hens resume once the trigger passes.
### Do all hens lay for the same number of years?
No. Longevity of lay varies by breed, management, and individual bird. Age at first egg is a separate trait from how long a hen continues to lay.
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## Sources
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2. [Research note: Genetic background influences the relationship between age at first egg and long-term egg production in layers.](https://pubmed.ncbi.nlm.nih.gov/42731209/)
3. [Short communication: Evaluating laying curve models and estimating genetic parameters for egg production traits in chickens.](https://pubmed.ncbi.nlm.nih.gov/40088526/)
4. [Genome-wide association study reveals candidate genes associated with egg-laying performance in Wuhua yellow chicken.](https://pubmed.ncbi.nlm.nih.gov/40884866/)
5. [Comparison of keel bone traits, eggshell production, and physiological parameters between a hybrid layer and two low-performing chicken genotypes.](https://pubmed.ncbi.nlm.nih.gov/41907534/)
6. [Estimating genetic parameters of egg production in three local Tanzanian chicken ecotypes.](https://pubmed.ncbi.nlm.nih.gov/41880929/)
7. [Effect of age at photostimulation on sexual maturation and egg-laying performance of layer breeders.](https://pubmed.ncbi.nlm.nih.gov/32029163/)
8. [Effect of age at photostimulation on reproductive performance of Beijing-You Chicken breeders.](https://pubmed.ncbi.nlm.nih.gov/31127838/)
9. [Laying hen performance as influenced by protein intake to sixteen weeks of age and body weight at point of lay.](https://pubmed.ncbi.nlm.nih.gov/8202428/)
10. [Effects of feeder space allocations during rearing, female strain, and feed increase rate from photostimulation to peak egg production on broiler breeder female performance.](https://pubmed.ncbi.nlm.nih.gov/24795295/)
11. [Evaluation of infectivity, length of infection, and immune response of avian reovirus variants in egg-laying hens.](https://pubmed.ncbi.nlm.nih.gov/39499533/)
