Tool
Backyard Egg Production Calculator: Eggs per Week by Hen Age
How many eggs will your flock actually lay? Enter how many hens you have in each age group and the calculator applies published year-by-year lay figures to give an upper-end estimate of eggs per week and per year. The formula and every number it uses are listed below the tool.
Upper-end estimate on natural light, averaged over a full year. Real weekly output swings with season, molt and broodiness.
How the calculator works
For each age group the calculator multiplies the number of hens by the first-year figure for your hen type and by that group's multiplier, then adds the groups together:
Eggs per year = Σ (hens in group × first-year eggs per hen × group multiplier)
Eggs per week = eggs per year ÷ 52
Feed per week = all hens × 0.25 lb × 7 days
| Input | Value used | Where it comes from |
|---|---|---|
| Age at first egg | About 18 weeks; younger birds count as zero | Purina says most hens lay their first egg around 18 weeks; UF/IFAS gives 18–22 weeks and Oregon State 18–20 weeks |
| First-year eggs, high-producing hen | 250 | Purina: well-fed, high-producing backyard hens "can lay up to 250 eggs" in their first year |
| First-year eggs, White Leghorn | 265 | Oregon State: the average commercial Single Comb White Leghorn lays about 265 eggs a year, with backyard breeds laying fewer |
| First-year eggs, bantam or Silkie | 50 | Purina: Silkies and bantams "may lay closer to 50 eggs" in their first year |
| Year 2 multiplier | 0.80 | Purina: about 80% of first-year production |
| Year 3 multiplier | 0.70 (upper bound) | Purina: "just under 70%" of first-year production |
| Year 4 multiplier | 0.60 | Purina: about 60% of first-year production |
| Year 5+ multiplier | 0.60 (ceiling only) | No published figure; Purina says production keeps falling until hens enter "egg retirement" around years six or seven, so the year-4 rate is used as a ceiling |
| Feed per hen | 0.25 lb per day | Purina: laying hens eat about a quarter-pound of complete feed a day, roughly one-half cup |
Two of these choices are ours rather than the sources': applying Purina's year-on-year percentages to Oregon State's Leghorn and Purina's bantam figures, and using the year-4 rate as a ceiling for older hens. Both push the result toward the high side.
Cross-check with flock lay rate
Extension services often describe production as a flock lay rate — the share of hens laying on a given day. The University of Florida reports that a flock rises to a peak of about 90% six to eight weeks after laying begins, then gradually declines to about 65% after 12 months of lay. Oregon State puts peak production at about 35 weeks of age at a rate above 90%, lasting about ten weeks. Converted to eggs per hen per week:
| Flock lay rate | When (source) | Eggs per hen per week | Eggs per week, 6 hens |
|---|---|---|---|
| 90% | Peak, 6–8 weeks after first egg (UF/IFAS) | 6.3 | about 38 |
| 65% | After 12 months of lay (UF/IFAS) | 4.6 | about 27 |
A young flock near peak will therefore lay well above the annual average the calculator shows, and the same flock a year later will lay below it.
Why your count may come in lower
- Short days. Hens need about 14 hours of day length to maintain production (UF/IFAS); Oregon State says day length must stay above 12 hours, with 14–16 typical. See supplemental lighting.
- Molt. Good layers lay for about 50 to 60 weeks and then rest during a molt (UF/IFAS). Expect a pause in laying while a hen molts.
- Parasites. UF/IFAS reports that lice can cut flock production by as much as 10%, and heavy infestations by as much as 20%. See mites and lice.
- Breed. Oregon State notes that backyard breeds generally lay fewer eggs than commercial Leghorns, and that "the more exotic the breed, the poorer the egg production." If your hens are not high-production types, use a custom first-year figure.
- Individual hens. UF/IFAS stresses that the drop after two or three years "varies greatly from bird to bird."
Using the estimate to plan a flock
- Decide how many eggs your household uses in a week.
- Enter your current or planned hens and compare the weekly figure against that need.
- Move every hen down one row to see next year's output. If the drop is too steep, plan to add pullets; they will not lay until roughly 18–22 weeks of age.
- Check the feed line. Older hens eat the same quarter-pound a day while laying less, which is the trade-off covered in how long hens keep laying.