Why use this calculator
Small flock owners consistently overestimate winter production and underestimate feed cost, and the two errors compound into disappointed customers and an egg enterprise that quietly loses money. Production is not a single number: it moves with breed, with the age of the flock and above all with day length, so the same sixty hens that fill trays in October can barely keep the house going in July.
This calculator shows the current rate and the annual average separately so you can commit to customers on the figure that will hold across a year. It also converts feed into a cost per dozen, which is the number that decides whether your farm gate price is a business or a hobby, and puts a weekly margin over feed at the bottom.
How to use it
- Enter the number of hens in lay, counting only birds that are laying or about to start.
- Choose the breed, or the closest type if you run a mixed backyard flock, since baseline output varies from about one hundred and eighty five to about three hundred eggs a hen each year.
- Select the age of the flock, because production peaks in the first laying year and falls by roughly fifteen per cent every year after.
- Pick the current season, which sets how far above or below the annual average the flock is sitting today.
- Choose your hemisphere so the month by month table maps calendar months to the right seasons.
- Enter the grams of layer ration each bird eats per day and the delivered ration price per tonne.
- Finally enter what you sell a dozen for, or what you would otherwise pay at the shop.
What each result means
- Eggs per day
- What the whole flock should be laying today at the season, breed and age you selected.
- Hen day lay rate
- The industry measure of production: the percentage of hens laying on any given day. One hundred per cent means an egg from every hen.
- Eggs per week
- Seven days of production, which is the unit most small flock customers order and collect in.
- Dozens per week
- Weekly output converted to dozens, ready to match against standing orders and market stall commitments.
- Eggs per hen per week
- Per bird production, useful for spotting an underperforming flock against the five to six eggs a good hen should give.
- Eggs per month
- Production over an average calendar month of 30.44 days at the current seasonal rate.
- Annual estimate for the flock
- Whole year output averaged across all four seasons, which is the figure to use for supply commitments.
- Feed used per day
- Kilograms of layer ration the flock eats each day, useful for planning deliveries and silo or bin capacity.
- Feed cost per dozen
- The ration cost behind every dozen produced. Compare it against your selling price to see the feed margin.
- Feed cost per week
- Seven days of ration cost, the single biggest recurring expense in a laying flock.
- Egg income per week
- Weekly dozens multiplied by the price you sell at, before any grading, carton or stall costs.
- Margin over feed per week
- Income less feed. Housing, replacement birds, bedding and labour all have to come out of this.
- Margin over feed per hen per week
- The weekly margin over feed divided across the flock, so you can see what one bird earns and judge when an older hen stops paying her way.
The formula
Annual eggs per hen equals the breed baseline multiplied by the age factor, where the baselines are ISA Brown or hybrid 300, Leghorn 280, Rhode Island Red 250, Australorp 240, Sussex 215 and heritage or mixed 185 eggs per hen per year, and the age factors are point of lay 0.55, first year 1.0, second year 0.85, third year 0.72 and fourth year or older 0.58. The current rate multiplies that by a season factor of spring 1.12, summer 1.02, autumn 0.85 and winter 0.62. Hen day lay rate equals eggs per hen per day expressed as a percentage. Feed cost per dozen equals daily feed cost divided by dozens produced that day.
How this number is used in practice
The number that catches people out is the annual average rather than the peak. A flock of sixty good hybrids in their first year can fill fifty five eggs a day through a warm spring, and the same flock in mid winter drops to around thirty.
If you sign up customers on the spring rate you will spend July buying eggs to cover your own orders. Commit on the annual figure, sell the spring surplus as a seasonal extra, and everyone stays happy. Staggering flock ages so that a new batch of pullets comes into lay every twelve months is the standard way to flatten the curve without artificial light.
Feed cost per dozen is the reality check. Layer ration is typically eighty per cent or more of the running cost of a small flock, and a hen eats roughly the same amount whether she is laying well or not. That is why a third or fourth year flock quietly becomes expensive: the feed bill is flat while production has fallen by a quarter or more.
Working out the cost per dozen at your current age and season, then comparing it against the price of replacement pullets spread over a laying year, is the calculation that tells you when to cull.
Day length is the lever, not temperature. Hens need roughly fourteen to sixteen hours of light to hold peak lay, and the drop after the autumn equinox is a light response rather than a cold one. A timer adding light in the early morning to reach fourteen hours will hold winter production substantially higher, at the cost of a slightly shorter productive life.
Many small producers prefer to accept the winter dip and let the flock moult naturally, which is a legitimate choice as long as the supply promises match it.
Worked examples
60 first year hybrids in spring on a $900 ration selling at $8 a dozen
About 55.2 eggs a day at a 92 per cent lay rate, and 18,000 eggs across the year.
The same flock in mid winter
Production falls to about 30.6 eggs a day at a 51 per cent lay rate.
A dozen third year Australorps in autumn
About 4.8 eggs a day from twelve hens, roughly 2,074 eggs a year.
When people use it
- Committing to farmers market or box scheme orders you can supply all year, not just in spring
- Working out the feed cost behind a dozen eggs before you set a farm gate price
- Deciding when an ageing flock stops paying for the ration it eats
- Sizing a first flock so household egg use is covered without a permanent surplus
- Planning staggered pullet intakes to flatten the seasonal production curve
- Checking whether an underperforming flock is simply seasonal or genuinely unwell
Tips
- Commit to customers on the annual average, not the spring peak, or you will be buying eggs in winter to cover your own orders.
- Fourteen to sixteen hours of light holds winter production. Add it in the early morning with a timer rather than at night.
- Keep shell grit and a calcium source available separately. Thin shells show up long before lay rate falls.
- Track eggs collected per day for a fortnight before blaming a breed. Most sudden drops are lice, mites, a fright or a hidden nest.
- Stagger flock ages by bringing in pullets every twelve months so production never all falls away at once.
- Expect an annual moult of six to twelve weeks with little or no lay. It is normal, and forcing through it rarely pays.
- Weigh a bag of feed against actual days used once a season. Spillage and vermin waste far more ration than most owners assume.
What it assumes, and where it stops being accurate
- Breed baselines are typical first year figures under good management, feed and housing. Poor conditions cut them sharply.
- The seasonal factors assume a temperate climate with a normal day length swing and no artificial lighting.
- Annual estimates average the four seasons rather than holding the current season's rate all year.
- Moult, broodiness, disease, predation and heat stress are not modelled and can each remove weeks of production.
- Feed intake is treated as constant per bird. In practice birds eat more in cold weather and less in heat.
- Only feed cost is counted in the margin. Replacement pullets, housing, bedding, cartons, labour and losses all sit on top of it.
Terms used on this page
- Hen day lay rate
- The percentage of hens in a flock that lay on a given day.
- Point of lay
- A pullet at around eighteen to twenty two weeks, just about to start laying.
- Moult
- The annual replacement of feathers, during which hens usually stop laying for six to twelve weeks.
- Layer ration
- A balanced feed for laying hens, typically around sixteen to eighteen per cent protein with added calcium.
- Margin over feed
- Egg income less feed cost, before housing, bird replacement and labour.
Questions people ask
- What is hen day lay rate?
- It is the percentage of hens in the flock that lay on a given day, and it is the standard measure across the egg industry. A hundred hens producing eighty eggs are at an eighty per cent hen day rate. Good commercial hybrids peak in the low nineties, and a small mixed flock sitting near sixty per cent across a year is doing well.
- Why does egg production drop so much in winter?
- Laying is triggered by day length, not temperature. Hens need roughly fourteen to sixteen hours of light to hold peak production, and once daylight falls below that after the autumn equinox the rate falls with it. Cold weather adds to the effect by diverting energy into keeping warm, but light is the main driver.
- How long do hens keep laying well?
- Production peaks in the first laying year and typically falls around fifteen per cent each year afterwards, while feed intake stays much the same. Most commercial flocks are replaced after one or two laying years. Backyard hens often keep laying at a reduced rate for four or five years and remain worth keeping for other reasons.
- How much feed does a laying hen eat?
- A commercial hybrid eats roughly 115 to 125 grams of layer ration a day, which is about 45 kilograms a year. Larger heritage breeds eat more for fewer eggs. Feed is usually eighty per cent or more of the running cost of a small flock, so intake and ration price drive the cost per dozen almost entirely.
- Should I use artificial light to keep winter production up?
- It works, and adding light in the early morning to reach fourteen hours will hold production substantially higher through winter. The trade off is a slightly shorter productive life, since a hen has a finite number of ova. Many small producers prefer to accept the dip and let the flock moult naturally.
- Why has my flock suddenly stopped laying?
- The usual causes are moult, a sudden drop in day length, mites or lice, a predator scare, a change of feed, heat stress or a hidden nest somewhere in the yard. Check under the perches at night for mites and search for a new nesting spot before concluding the birds have finished laying.
Use this with
Egg Production Calculator answers one part of the question. These pick up where it stops: Livestock Feed Calculator, Stocking Rate Calculator, Livestock Gestation Calculator, Cost Per Hectare Calculator and Water Tank & Dam Volume Calculator.
Where these figures come from
Figures and rules on this page follow Australian law and ATO guidance.
- Australian Eggs. Layer flock performance, husbandry and small flock husbandry information
- NSW Department of Primary Industries. Primefacts on stocking rates, soil acidity, livestock nutrition and breeding
- Agriculture Victoria. Extension notes on pastures, soils, liming and livestock management
- United States Department of Agriculture. US grain standards, bushel weights and livestock production statistics
Egg Production Calculator produces an estimate for general information. It is not financial, tax, medical, legal or engineering advice. read the full disclaimer. Spotted a wrong number? Report it and it gets fixed. The form picks up this calculator and the inputs you used.