Poultry mortality rate calculator
Cumulative mortality is deaths divided by birds placed, as a percentage. Under 5% over a broiler cycle is good, 5–8% is workable, and above 10% means something is wrong that will not fix itself. Daily mortality rate is the earlier warning: it moves days before the cumulative figure looks bad.
Calculator
The values below are the worked example. Change them to match your own farm — the results update as you type, and nothing you enter leaves your browser.
- Birds remaining (birds)
- 478
- Cumulative mortality (%)
- 4.4
- Survival rate (%)
- 95.6
- Daily mortality rate (%)
- 0.417
- Average deaths per day (birds)
- 0.63
Placed less cumulative deaths. This is the number to use in every feed and revenue calculation.
The headline figure for the batch. Compare against the benchmark table below.
The mirror of mortality — often the figure buyers and lenders ask for.
Deaths today as a share of birds alive yesterday. Sustained above about 0.5% a day needs investigation now, not next week.
Cumulative deaths over days elapsed. Useful for spotting whether today is unusual.
Method, assumptions and limits
What this tool calculates
Calculates cumulative mortality, daily mortality rate, survival rate and birds remaining for a flock.
Who it is for
Any poultry farmer tracking flock health, and anyone comparing a batch against normal benchmarks.
Inputs it needs
- Birds placed — Chicks or pullets originally placed in the house.
- Total deaths so far — Cumulative deaths, including culls.
- Days since placement — Age of the flock in days.
- Deaths in the last 24 hours — Today's count, used for the daily rate.
Formula
birds remaining = placed - cumulative deathscumulative mortality % = cumulative deaths / placed x 100survival % = 100 - cumulative mortality %daily mortality % = deaths in last 24 h / (birds remaining + deaths in last 24 h) x 100
Worked example
500 birds placed with 22 cumulative deaths at day 35 leaves 478 birds alive — 4.4% cumulative mortality and 95.6% survival, which is a good result for a broiler batch. Two deaths in the last 24 hours against 480 birds alive yesterday is a daily rate of 0.42%, close to the point where it is worth walking the house carefully rather than waiting.
Assumptions
- Culled birds are counted as deaths, because they are equally lost from the sale.
- Birds placed is the true starting number, including any dead-on-arrival chicks you were credited for.
- The daily rate uses yesterday's live count as the base, which is the standard convention.
Limitations
- A percentage tells you the size of a problem, not its cause. It is a monitoring tool, not a diagnosis.
- Very small flocks produce jumpy percentages — one death in 20 birds is 5%. Read the trend, not a single day.
- Benchmarks are general commercial ranges; your strain, climate and system will shift what 'normal' looks like.
What normal looks like
| Flock type and period | Good | Acceptable | Investigate |
|---|---|---|---|
| Broilers, whole 42-day cycle | Under 4% | 4–7% | Above 8% |
| Broilers, first 7 days | Under 1% | 1–2% | Above 3% |
| Pullets, 0–18 weeks | Under 4% | 4–6% | Above 8% |
| Layers, per month in lay | Under 0.5% | 0.5–1% | Above 1.5% |
| Any flock, single day | Under 0.1% | 0.1–0.3% | Above 0.5% |
Reading the shape, not just the number
- A spike in the first 3 days: chick quality, transport stress, or the house was not warm enough before chicks arrived.
- A steady low trickle throughout: usually normal, especially in the last week as heavier birds struggle.
- A sudden sharp rise after day 14: treat as a disease or water event and involve a qualified animal health professional immediately.
- A rise that matches the hottest days: heat stress. Check ventilation, water temperature and stocking density.
- Deaths concentrated in one part of the house: a local problem — a draught, a failed drinker line, a wet patch of litter.
What happens to the numbers you type
This calculator runs in your browser only. Flock counts are not transmitted or stored, and no result URL is generated. Daily mortality you want to keep belongs in your farm records inside the app, tied to your account.
Sources
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