Why Do Chickens Lay Eggs Almost Every Day? A 25-Hour Egg and a Day Off

Here’s the short answer: they don’t, quite. A hen lays in runs, with a day off between them. Dr. Jacquie Jacob of the University of Kentucky says it takes “about 25 to 26 hours” to turn a yolk into an egg and lay it. The next yolk usually goes 30 to 75 minutes after she lays. So each egg comes a little later in the day than the one before. And since a hen almost never releases a yolk after 3 p.m., a late egg means a day with no egg. Jacob calls those runs clutches. At her best, Oregon State says, a good hen lays about 9 eggs in 10 days. My read: light, breeding, age and health decide how many runs she has in her, and that’s what the rest of this page is about.

I rewrote this page from 15 sources, all listed at the bottom. The egg-making steps are from Jacob’s page on the hen’s reproductive system, on extension.org. Oregon State’s guide by James Hermes covers why hens stop laying. Penn State gave me two pages: Ashley Bigge’s on winter lighting, and Phillip Clauer’s on keeping a small laying flock. Ashley Wright of the University of Arizona wrote the other lighting page. The part about light and the skull is from a 2020 review in Frontiers in Physiology. The wild nests are from a study of red junglefowl on Hainan Island in China. Where chickens came from is a 2020 genome study in Cell Research, which I read as a PubMed abstract. On shell color I used Hendrix Genetics, a 2015 Poultry Science review (also a PubMed abstract), Washington State University’s Ask Dr. Universe, and the USDA’s Agricultural Marketing Service. Alabama Extension, Purina’s Layena product page and a 2014 paper on feeding hens marigold fill in the rest.

A word on the photos. The tray of brown eggs is from a farmers market in Oakland, California, in September 2016. Lance Cheung shot it for the U.S. Department of Agriculture. The caption says the eggs come from “free range chickens who produce organic eggs that are sold at urban farmers markets”. Preston Keres took three more for the USDA. One is a layer farm in San Sebastian, Puerto Rico. The USDA caption says its “chickens live under a dawn and sunset light-simulator to help promote a healthy egg production”. Another is a rooster and a white hen at a National Egg Day event at USDA headquarters in 2017. The third is a white egg in a grader’s fingers in 2018. Its caption says USDA “Shell Egg Graders candle eggs looking for defects”. Bob Nichols took the grading line of brown and white eggs at Cal-Maine Foods in Green Forest, Arkansas, in 2010. The white hen with her chick is Tamsin Cooper’s, from September 2019. The red junglefowl is Vikas Pawar’s, from the Flickr account Random Subjects. It was shot in 2018, the same morning as a Lineated Barbet and an Oriental Magpie Robin, so my read is that it’s a wild bird. Its page doesn’t say where. None of the egg photos says which hens laid which eggs, so the colors are all they show you.

The old page opened with a story I can’t back up. “Last summer, my wife and I decided to get chickens” is gone, and so is “For weeks I watched those fuzzy little poop machines”. So is “Every morning, I’d let the hens out and wait eagerly”. The two asides that went with it are out too. One was “Too bad my chickens’ eggs will just end up in omelets and cakes”. The other was “No wonder my chickens go nuts over their layer feed”. I can’t show you any of that happened.

Some of the facts were off, too. It said the next yolk gets released “several hours before the previous egg is laid”. Jacob has it the other way around: the next yolk goes 30 to 75 minutes after. And “an egg almost every 24 hours” is, by my math from Jacob’s numbers, really an egg about every 25 and a half to 27 and a quarter hours. I cut “which would take a human over 22 years to match” and “Ten hours of darkness neatly divides the 24-hour laying cycle”. I also cut the farms keeping lights on “16-18 hours per day”, since I found no source on what egg farms run. For a home flock, Penn State says not to go over 16, and Arizona says more than 16 adds no eggs. The line that “light enters the eye” went, since blind hens lay at about the same rate as sighted ones. And “Scientists have also found” a breed difference, with no study named, so that’s out.

The wild hen part said “They lay clutches of 10-15 eggs”. None of my sources gives that number, so it’s out. The Hainan study below counted about five. I found no source for “then eat discarded eggs after hatching”, or for “Mother hens seem to know the eggs will nourish their chicks”. The egg’s “6 grams of protein” is out, since I didn’t check egg nutrition this time. So are the “50 calories”, the “700 calories” and “3x the calories of regular chickens”. On color, it said “The earthy tones of brown eggs are a result of the chicken’s diet, too”, and named “marigold petals or paprika”. My sources tie marigold to the yolk, not the shell. I found nothing for “more visible with certain stamps and prints”. None of my sources uses the name “oocyanin” for the blue. Hendrix says blue shells come from biliverdin, so that’s the name I use. And “the taste of eggs can be influenced by their shell color” doesn’t hold up. Penn State says shell color makes no difference to taste.

The short version.

• An egg takes about 25 to 26 hours, and the next yolk goes 30 to 75 minutes after she lays (Jacob).
• A hen almost never releases a yolk after 3 p.m. So her eggs come a bit later each day until she skips one. Those runs are clutches (Jacob).
• At her peak, around 35 weeks old, a good hen lays about 9 eggs in 10 days (Oregon State). A commercial White Leghorn averages about 265 a year. That’s about five a week, by my math.
• No rooster needed. A rooster is only for fertile eggs (Penn State, Alabama).
• Light is the switch. Keep the day above 12 hours, aim for 14 to 16, and don’t go over 16 (Oregon State, Penn State, Arizona).
• Wild red junglefowl on Hainan laid about five eggs a clutch, and the study thinks they may nest more than once. Commercial sex-linked hybrids lay 240 to 280 eggs a year (Penn State).
• She stops for short days, molt, a broody spell, age, poor feed, disease or stress (Oregon State). Collect eggs daily to keep broodiness down.
• Each shell takes 20 or more hours, and some of its calcium comes out of her bones (Jacob).
• Shell color comes from the breed. It doesn’t change taste or nutrition (Penn State), or the egg’s quality (USDA).

An Egg Takes About 25 Hours, So a Hen Can’t Lay One Every Day

Let’s start inside your hen. Jacob’s page follows a yolk down the oviduct, a twisted tube 25 to 27 inches long in a grown hen. Here’s the trip, with Jacob’s times.

• Infundibulum, 15 to 17 minutes. This is where the yolk gets picked up. Jacob writes “Fertilization, if it is going to occur, takes place in the infundibulum”.
• Magnum, about 3 hours. The thick white goes on here.
• Isthmus, about 75 minutes. The shell membranes go on.
• Shell gland, 20 or more hours. The shell goes on here, and any color too.
• Vagina. The bloom (the cuticle) goes on, and the egg turns and comes out large end first.

That’s more than a day, start to finish. Jacob puts the whole thing at “about 25 to 26 hours”. Then “Typically, about 30 to 75 minutes after a hen lays an egg, the ovary releases the next ovum”. So by my math, each egg in a run comes about an hour and a half to three and a quarter hours later in the day than the last one. That’s 25 hours plus 30 minutes at the short end, and 26 hours plus 75 minutes at the long end.

Here’s the catch, and it explains the empty nest box you’ll find now and then. Jacob says a hen ovulates “almost never after 3:00 p.m.” So if she lays too late in the day, “the next ovulation occurs the following day”. Then “the hen has a day when it does not lay an egg.” That’s the day off. Jacob calls each run a clutch. “A clutch is a group of eggs laid by a hen on consecutive days.” After one, the hen rests “about a day or more”. Then she starts the next.

My read: that’s why even a great layer can’t quite manage one a day. Oregon State says a pullet starts at 18 to 20 weeks and peaks at about 35 weeks, at better than 90 percent. It spells that out as “9 eggs in 10 days for a single hen”. The peak “lasts about 10 weeks, after which her egg production slowly begins to decline”. It adds that the “average commercial Single Comb White Leghorn hen lays about 265 eggs per year, with backyard breeds laying fewer”. By my math, 265 a year is about five eggs a week, averaged over the year. Want a number for your own hens? Our egg production calculator gives each hatchery’s own figure for your breed, plus what day length and your hens’ ages do to it.

No Rooster Needed, Since He Only Makes the Egg Fertile

You might not expect this one. Hens lay with or without a rooster. Penn State’s small flock page says “Roosters are not necessary in a flock for hens to lay eggs.” Alabama Extension puts it another way. “Roosters, of course, are not needed for egg production but for fertile egg production.” Jacob’s “if it is going to occur” says the same thing from the inside. Your hen builds the whole egg either way. A rooster only adds the chance of a chick inside it.

Here’s what the egg is for, in Jacob’s words. “All the nutrients needed for an embryo to fully develop are provided in the egg before it is laid.” My read is that the hen’s body doesn’t wait to find out if there’s an embryo. It just makes the egg. And if you’ve just taken a rooster out, don’t count on unfertilized eggs the next day. Jacob says a hen stores sperm in glands where the shell gland meets the vagina, “typically 10 days to 2 weeks”. The beginner’s guide to egg-laying chickens lands the same way on roosters, with the same Penn State line.

Light Is the Switch, Not the Cold

If you take one thing from this page, make it this one. Penn State’s lighting page says “Photoperiod (hours of light per day) directly influences the production of reproductive hormones”. Arizona’s page calls it a common misconception that “cold temperatures in the wintertime lead to decreased egg production”. It’s the short days.

Oregon State gives the numbers. In Oregon, the day drops from nearly 16 hours of light at the start of summer to just over 8 at the start of winter. That drop makes hens molt and stop laying. To keep them going, it says “day length must increase or remain constant at more than 12 hours per day; a 14- to 16-hour day is typical”. Penn State says to aim for 16 hours and “Be careful not to go over this”. It also says to change the day by “no more than 1 hour difference each week”. Arizona’s limit is the same: “a photoperiod greater than 16hrs does not stimulate additional egg production”.

If you do add light, stick with it. Oregon State warns “Even a 1-day lapse can have a negative impact on egg production”. Arizona says forgetting the lights for a day or two can set off a molt that drops laying “for 6-8 weeks”. So put your light on a timer. Oregon State says it needs to be “just bright enough to read a newspaper, and the type of bulb does not matter”. Penn State says “Chickens need orange and red wavelengths of light for reproduction”, and to look for warm bulbs “rated less than 3500K”. It adds that a daylight or white bulb “will also work as long as it is not too green or blue”. Arizona asks for warm light over cool. My call: get the warm bulb, since Arizona asks for one and Penn State prefers one. Arizona adds a warning: “Heat lamps carry a large risk of fire”. Don’t use one as your light.

You might worry that extra light wears a hen out. Arizona says “Supplemental lighting, when used correctly, does not harm hens or shorten their laying lifespan”. By correctly it means good feed, “particularly with adequate calcium”, and no more than 16 hours of light a day. The reason it gives is “Hens are born with many more egg follicles than they will lay in a typical lifetime”. Jacob’s version is that a pullet chick hatches with “tens of thousands of ova”, and no new ones form after. Penn State says the other way is fine too: “It does not harm the birds to allow them to molt naturally.” They lay again in spring. My call: both are fine. Add light slowly if you want winter eggs, or give them the winter off.

Now the strange part. The old page said light goes in through the eye. A 2020 review by Hanlon and three colleagues says “blind laying hens have a similar rate of egg production when compared to their sighted counterparts”. That’s from a 1980 study. Back in 1935, a study on ducks put a black cap over their heads, and “the gonadal response was inhibited”. The review says that “implied that the avian skull is permeable to light”. Arizona’s page credits the pineal gland, near the center of the brain. The review points to light receptors deep in the brain, in the hypothalamus, which “have been identified as the potential mediators”. Either way, my read is that the light gets to her brain through her skull, and her eyes aren’t the whole story.

Wild Junglefowl on Hainan Lay About Five Eggs a Clutch

Your backyard hen started out as a wild bird. A 2020 study of 863 genomes suggests that “domestic chickens were initially derived from the RJF subspecies Gallus gallus spadiceus”. RJF is red junglefowl. That subspecies lives mostly in southwestern China, northern Thailand and Myanmar today. The abstract opens by saying where and when chickens were first tamed “remain controversial”, and that’s the question the study set out to answer.

The wild birds don’t lay like a backyard hen. Researchers on Hainan Island, China, followed red junglefowl nests in 2020 and 2021. Those were a different subspecies, G. g. jabouillei. The paper says “The clutch size was 5.15 ± 1.28 ( n = 13)”. That’s about five eggs, from 13 nests. The paper says that’s about the same as the Indian subspecies, but “significantly lower than that of the southern Yunnan subspecies”. That’s spadiceus, the one the genome study names. Breeding ran mainly from March to July, with the peak in April. The paper set its test nests at 19 days, which it says is similar to the natural incubation period. Only about 31% of the natural nests succeeded.

That’s one clutch, not a year. The paper thinks the Hainan birds may nest more than once, and none of my sources gives a wild hen’s yearly total. Domestic hens get counted by the year. Penn State says “Common heritage type breeds will lay 50 to 100 eggs a year.” And “Commercial sex-linked hybrids will lay 240 to 280 eggs a year.” On modern commercial chickens, the 2020 review says “Decades of genetic selection along with significant improvements in environmental conditions and nutrition” have made them “exceedingly efficient”. My read is that part of the difference is sitting. A wild hen sits on her clutch. Oregon State says “broodiness is rare in Leghorns”, the commercial white layer behind its 265 eggs a year.

Why She Stops: Short Days, Molt, a Broody Spell or Age

Oregon State lists “decreasing day length, disease, broodiness, poor nutrition, and stress” as the most common reasons hens stop. Short days are covered above. Here are four more you’ll run into.

• Molt. Penn State says that in the United States it comes “most often in September and October when the photoperiod reaches and dips below 12 hours per day”. She drops old feathers and grows new ones, and laying stops for a while. Oregon State says the molt “rejuvenates her oviduct”. If you’ve been adding light, it suggests letting hens molt in their second winter.
• A broody spell. Oregon State says “When a hen becomes broody, hormonal changes result in the cessation of lay.” It adds “Cochins and Silkies are champions at going broody”. The usual trigger “is a nest full of eggs”, so collect eggs daily from nests and hiding places.
• Age. Oregon State says hens “produce well until they are 2 to 3 years old, and then egg production declines”. By the time a high-producing hen has laid for 3 years, it says she “may have produced more than 30 times her body weight in eggs”.
• Feed. Oregon State says “Do not feed starter or grower diets to layers”. The calcium part is next.

Every Shell Borrows Calcium From Her Bones

Here’s the costly part. Jacob says the egg stays in the shell gland “20 or more hours”, and Hendrix Genetics says about 20. That’s most of the 25. The shell is mostly calcium carbonate. Jacob says the hen’s body moves “8 to 10 percent of body calcium from its bones” to make one shell. And “Bone calcium provides 47 percent of the calcium required to make a shell”. Her feed covers the rest.

That’s why the layer feed you buy is heavy on calcium. Purina’s Layena page lists 3.25% to 4.25% calcium. Oregon State also says to “provide free-choice oyster shell in a separate feeder”. Purina says most flocks on Layena shouldn’t need the extra, but that “it is good practice to place a dish of oyster shell out during hot weather”. It’s not for young birds. Penn State says “Feed a layer ration from 18 weeks on”, and Purina’s page says “Do not feed to birds less than 18 weeks of age”. In the post on chicks and adult feed, I went through why that much calcium is hard on young birds’ kidneys, and when to switch.

Shell Color Is the Breed, Rarely the Feed

Every egg starts out white. Ask Dr. Universe says “all bird eggs start out white”, and the pigment goes on in the shell gland, Jacob says. Hendrix Genetics sorts the colors like this.

• White. These hens “lack the ability to deposit pigments in the eggshell”. The Leghorn is the common one.
• Brown. The 2015 review says “The major pigment in eggshells of brown-egg laying hens is protoporphyrin IX”. Most of it sits “in the outermost layer of the calcareous shell and in the cuticle”. Rhode Island Reds lay brown.
• Blue and green. Breeds like Araucanas “carry a genetic variation that allows for the deposition of biliverdin, resulting in blue and green eggshells”.
• Tinted. These come from crossing white-egg and brown-egg chickens.
• Dark brown. That’s Marans, a French breed.

The brown sits mostly on the outside of the shell, and it goes on late. Hendrix says most of the pigment isn’t moved to the cuticle “until the last 3 to 4 hours of shell production”. The pigment-rich cuticle goes down about 90 minutes before she lays.

You may have heard the earlobe rule. Ask Dr. Universe reports it from Rocio Crespo, a WSU veterinarian: if a chicken’s earlobes are white, the column says, “the eggs it lays tend to be white”. The column adds a catch in its own words. “Some chickens with red earlobes may also lay greenish eggs or blue eggs.” So it’s a rule of thumb.

My read: feed rarely changes shell color much. Hendrix does count diet among the factors, but calls a diet effect “atypical”. It ties one to a shortage of nutrients, or a drug like nicarbazin, which gives pale eggs. The 2015 review does list diet among the things that change how much pigment goes on. Its list also has the housing system, the hen’s age and strain, stressors, and certain diseases. In my sources, marigold is a yolk thing. A 2014 paper on feeding hens marigold says yolk color “is produced by carotenoid pigments in the feed”, and that marigold is “commonly used in the pigmentation of eggs”.

So whatever color you collect, it’s the same egg on the inside. Penn State says “Eggshell color is determined by the breed and makes no difference in the nutritional value or taste of the egg.” The USDA’s marketing service says “Shell color does not affect the quality of the egg”. It does add that brown eggs run bigger on average, because of the breed.

Sources

• Jacquie Jacob, University of Kentucky, on extension.org: Avian Reproductive System, Female.
• J.C. Hermes, Oregon State University Extension (a Pacific Northwest Extension publication): Why Did My Chickens Stop Laying? PNW 565 (January 2003).
• Ashley Bigge, Penn State Extension: Artificial Lighting for Winter Egg Production (updated September 9, 2025).
• Phillip J. Clauer, Penn State Extension: Successfully Raising a Small Flock of Laying Chickens.
• Ashley Wright, University of Arizona Cooperative Extension: Lighting Schedules for Arizona Backyard Laying Flocks, AZ2185 (January 2026).
• Hanlon and colleagues, Frontiers in Physiology 2020: Should I Lay or Should I Grow.
• Rao and colleagues, Frontiers in Ecology and Evolution 2023: Nesting success and potential nest predators of the red junglefowl (Gallus gallus jabouillei).
• Wang and colleagues, Cell Research 2020: 863 genomes reveal the origin and domestication of chicken (PubMed abstract).
• Samiullah and colleagues, Poultry Science 2015: eggshell color in brown-egg laying hens (PubMed abstract).
• Hendrix Genetics: Eggshell Color Eggsplained (September 19, 2023).
• Washington State University, Ask Dr. Universe (2016), with Rocio Crespo: Can You Tell What Color Eggs a Chicken Will Lay?.
• USDA Agricultural Marketing Service: Questions and Answers, USDA Shell Egg Grading Service.
• Wilmer Pacheco with Joseph Gulizia and Kevin Downs, Alabama Cooperative Extension System: Feeding the Laying Hen, ANR-2913.
• Purina Animal Nutrition: Purina Layena Pellets 16% Layer Hen Feed, product page.
• Altuntaş and Aydin, Journal of Lipids 2014: Fatty Acid Composition of Egg Yolk from Chickens Fed a Diet including Marigold (Tagetes erecta L.).

Sources checked November 3, 2026. I read the 2015 color review and the 2020 genome study as PubMed abstracts, not full papers. How much later each egg comes is my math from Jacob’s two numbers, and so is five eggs a week from 265 a year. That light reaches the brain through the skull is my read of the 2020 review. Adding winter light or giving hens the winter off is my call between my sources. Not counting on unfertilized eggs right after a rooster leaves is my read of Jacob’s line on stored sperm. We aren’t vets. If a hen stops laying out of season or looks sick, call a vet who sees poultry.

Related read: How to Raise Chickens for Eggs — Instant PDF download. Secure checkout by Stripe