Chicken Egg Laying Calculator

Egg laying by age, season and flock size

Six brown-egg hens at 30 weeks old lay about 39 eggs a week, a little over 3 dozen, and the same six at 90 weeks lay about 32. This chicken egg laying calculator works that out for your own flock from the hens' age, using the week-by-week laying rates that the breeder Hy-Line publishes for its brown and white commercial layers. It also turns a count you made yourself into a weekly and yearly forecast, tells you how many hens a household needs for a set number of eggs, checks the daylight for your month and latitude, and prices the feed per dozen.

93.6%

peak laying rate, Hy-Line Brown, week 26

14-16 h

of light a day for full production

70.8%

laying rate left at week 100

From the hen count to the feed bag

Number of hens - laying hens only, roosters left out. You can skip it if you only want to know how many hens a target needs.
Type of hens - a brown-egg layer (Hy-Line Brown curve), a white-egg layer (Hy-Line W-36 curve), or your own count for any other breed.
Age in weeks - from hatch, needed for both standards. A year is 52 weeks.
Eggs collected in the last 7 days - only with your own count, for the whole flock.
Month and latitude - optional, together they give the daylight on the 15th of the month and a warning below 14 hours.
Lighting - daylight only, or lights on a timer up to 14 hours.
Eggs you need per week - optional, returns the number of laying hens.
Feed per hen, bag price and bag weight - optional, for pounds a month and the feed cost of a dozen. An empty bag weight means 50 lb.

One flock, start to finish

6 brown-egg hens, 30 weeks old, December at about 40° N, a 50 lb bag at $24.99. Result: 39.2 eggs a week (3.3 dozen), 168 a month and 1,916 over the next 12 months as the flock ages. Feed runs 45.2 lb a month, or $1.62 per dozen eggs. The day is only 9 h 20 min long, so the calculator warns that with daylight alone the real count will sit well below the standard.

Why age matters more than breed names

The figures behind the calculator are hen-day rates: the share of hens alive that day that lay an egg. A rate of 93.3% means that out of 100 hens, about 93 lay on a given day, which is 6.53 eggs per hen per week. No hen lays more than one egg a day, so the ceiling is 7 a week, and the calculator refuses a count above that.

Both breeder standards follow the same shape. Laying starts around week 18, half the flock lays by day 139 (brown) or 143 (W-36) after hatch, the peak comes around weeks 26 to 30, and then the rate slides slowly for the rest of the hen's life. Over 100 weeks a brown hen in the standard lays 481.8 to 514.5 eggs and a W-36 hen 471 to 487.

These are commercial targets for flocks with controlled light and measured feed. The calculator takes the low end of each range, and a backyard flock that free-ranges, goes through winter on natural light and includes older hens will usually land below it. Heritage breeds have no published week-by-week standard of the same kind, which is why they go through the own-count option: count the eggs for a week and the calculator projects from there.

Laying rate by age in the two breeder standards

Low and high end of the hen-day rate, and the eggs per hen per week at the low end. Brown from the Hy-Line Brown conventional standard, white from the Hy-Line W-36 standard.

Age (weeks)	Brown, % hen-day	Brown, eggs per hen a week	White W-36, % hen-day	White, eggs per hen a week
18	6.7-7.0	0.47	2-3	0.14
20	52.5-55.0	3.68	35-50	2.45
22	87.0-91.2	6.09	80-84	5.60
26	93.6-98.5	6.55	94-96	6.58
30	93.3-98.2	6.53	95-97	6.65
40	91.9-97.2	6.43	93-94	6.51
50	90.0-95.6	6.30	89-91	6.23
60	87.4-93.2	6.12	86-88	6.02
70	83.6-89.8	5.85	82-84	5.74
80	79.7-86.1	5.58	77-80	5.39
90	75.4-82.0	5.28	72-75	5.04
100	70.8-77.6	4.96	67-70	4.69

Daylight by latitude, against the 14-hour line

Day length on the 15th of four months, as the calculator estimates it (sunrise to sunset, with atmospheric refraction). The last column shows how many months of the year stay under 14 hours.

Latitude	December	March	June	September	Months under 14 h
25° N (Miami)	10 h 35 min	11 h 57 min	13 h 41 min	12 h 16 min	all 12
30° N (Houston)	10 h 13 min	11 h 55 min	14 h 4 min	12 h 18 min	11
35° N (Memphis)	9 h 49 min	11 h 52 min	14 h 30 min	12 h 21 min	10
40° N (Denver)	9 h 20 min	11 h 50 min	15 h 0 min	12 h 24 min	9
45° N (Minneapolis)	8 h 47 min	11 h 47 min	15 h 36 min	12 h 27 min	8
48° N (Seattle)	8 h 23 min	11 h 45 min	16 h 1 min	12 h 30 min	8

Less obvious links between light, age and eggs

The South is not exempt. Further south the winter days are longer, but the summer days are shorter too. At 25° N the longest day in the table is 13 h 41 min, so by the 14-hour line a flock in South Florida never gets enough natural light for full production.

Cold is not the cause. The University of Arizona Extension calls the idea that winter cold cuts laying a common misconception: the drop follows the short day. That is why added light, not heat, is the fix it describes.

Morning light, not evening light. The same publication puts the extra hours before sunrise and warns that more than 16 hours brings no more eggs. Forgetting the lights for even one or two days can cause a drop, or a molt that stops laying for 6 to 8 weeks.

Feed per dozen climbs with age. Feed intake in the brown standard stays at 110 to 118 g a day from week 28 on, while the laying rate falls. Six brown hens at 30 weeks cost $1.62 of feed per dozen with a $24.99 bag; the same hens at 90 weeks lay 31.7 eggs a week on the same feed, and the dozen costs about $2.00.

Reading your result

How a weekly count per hen compares with the breeder standards, as a rough guide for a flock in its laying years.

Eggs per hen a week	Laying rate	What it suggests
6.0 to 7.0	86 to 100%	At the standard for hens of about 22 to 60 weeks
4.7 to 6.0	67 to 86%	Normal for older hens, the standard range from about week 60 to 100
under 4.7	under 67%	Below both standards: check daylight, a molt, the age of the flock and a breed that is not a commercial layer

A low number is not a diagnosis. Breeds kept for meat or looks lay less by nature, and the standards come from managed commercial flocks. If hens stop laying suddenly or look unwell, a veterinarian or your county extension office is the right next step.

Backyard flock questions

How many eggs does a chicken lay a week?

At the peak of the Hy-Line standards, around weeks 26 to 30, about 6.5 eggs a week. By week 60 it is about 6.1, and by week 100 about 5.0 for brown hens. A hen cannot lay more than 7 in a week.

How many hens does a family of four need?

At one egg a day per person that is 28 eggs a week. With brown hens at 30 weeks the calculator returns 5 hens; with a backyard flock laying 4.5 eggs per hen a week it returns 7.

Why did my hens stop laying in winter?

Most often because of the short day. At 40° N the day in December is about 9 h 20 min, far from the 14 to 16 hours hens need for full production. A molt can also stop laying for 6 to 8 weeks.

When do pullets start laying?

In both standards the first eggs come at 18 weeks and half the flock lays by day 139 (brown) or 143 (W-36) from hatch, roughly week 20 to 21.

How much feed does a laying hen eat?

The Hy-Line Brown standard gives 110 to 118 g a day in lay, about 0.25 lb, and the W-36 an average of 99.6 g, about 0.22 lb. What a backyard flock really takes from the feeder can differ from these standards, so weighing what disappears over a week gives the most honest figure.

Why is there no list of heritage breeds?

Eggs-per-year figures for breeds such as Orpingtons or Rhode Island Reds circulate widely but vary from source to source, and none publishes a week-by-week curve. A week of your own counting is a better basis, so the calculator uses that instead.

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