Give each requirement and tier a measured basis
Our estimates and tools are free to use when you write, tier, audit or revise a welfare standard. They show how much pain a requirement is likely to prevent, and for how many animals, in the same units across species and systems. Your scheme decides what to require and where to set each level.
The metric
The Welfare Footprint Framework (WFF) measures welfare as time spent in experiences of defined intensity. A Pain-Track shows time in four bands (Annoying, Hurtful, Disabling, Excruciating) and a Pleasure-Track does the same for positive experiences. Intensity, duration and prevalence are reported separately, so no weighting is hidden in a single score. For tiering, a robust common unit is time in intense pain (Disabling plus Excruciating) relative to a conventional baseline.
Intensity and duration are estimated by synthesizing behavioural, neurophysiological, pharmacological and evolutionary evidence against defined criteria, and are expressed as probabilities across four intensity categories rather than a single value. Prevalence comes from epidemiological evidence; where data are thin, it is given as an uncertainty interval. Each parameter is treated as a hypothesis with a stated uncertainty, and is updated as evidence accumulates. The main limitations, mostly sparse data on timing and prevalence, are set out in the FAQ. The framework does not prescribe whether to improve current systems or move away from them. It makes the welfare consequences of each option comparable. The method is the same for every estimate. What varies is the scope (species, system, life stages and region), and each estimate states its boundaries.
Start here: What is a welfare footprint? · The framework · Pain intensities · Uncertainty intervals
1. Set tiers by reduction in welfare impact
Each tier can require a stated reduction in time in intense pain compared with a conventional baseline. Two rules keep this robust:
- Set thresholds on ranges, not midpoints. A tier should hold at the lower end of the estimate's range.
- Match the estimate's scope. Check which harms, life stages and hours are counted before writing a percentage into a standard.
The published broiler estimate (broilers) is a minimum. It covers lameness, cardiopulmonary disorders, behavioural deprivation and heat stress, and counts hours awake only, so the true reduction is likely larger. Higher tiers can require slower growth, since the slower the growth rate, the higher the expected welfare impact. They can also cover parent flocks, because the full benefit depends on slower-growing parent lines too.
2. Choose which requirement to tighten
Rank candidate requirements by the intense pain they prevent and their cost. A standard helps only the animals on farms that adopt it, so cost shapes the welfare gain too.
For broilers, better management such as lower stocking density and enrichment helps, but its effect is limited while the harms of fast growth remain (broilers). A comment in Nature Food sets out the cost of slower-growing breeds alongside the pain they prevent (Schuck-Paim, Alonso, Verkuijl, Hegwood & Hartcher, 2025). The Welfare Impact Calculator compares a baseline with each option.
3. Check what a requirement adds and removes
A requirement can reduce some harms and add others. Count positive experiences and deprivation (frustration, loss of agency) as well as physical harms.
The WFF shows Pain and Pleasure side by side and doesn't treat one as cancelling the other, so whether the balance is positive is an empirical question. AffectMap, one of the AI-Assisted Tools, helps map harmful and beneficial pathways before any estimate is made.
4. Pick outcome measures that track welfare
Animal-based indicators, such as gait, injuries and behaviour, sit closer to what the animal experiences than resource-based ones such as space or drinker numbers (Welfare metrics and welfare indicators).
Lameness, the most serious welfare concern for the average broiler (broilers), is better recorded as the share of birds in each gait score than as one average, with compliance verified through third-party audits. The same records later show whether a tier delivers the reduction it was set for.
5. Benchmark and revise
Estimates show where intense pain remains under an existing standard, which is where a revision can focus. For laying hens, cage-free aviaries are clearly better than conventional and furnished cages, but keel bone fractures, ailments linked to breeding for productivity and egg peritonitis remain (laying hens).
Where no estimate exists yet, draft one with the AI-Assisted Tools. Their outputs are structured drafts, not Welfare Footprint estimates, so have them reviewed by experts before they shape a requirement. The Estimates Dossier, still being built, will show work under way.
Keep going
- Learn the method: Workshops · Office Hours
- Contribute data, such as outcome records from audited farms: For researchers
- Speed up an estimate your standard needs: Funding and philanthropy. Support brings a public estimate sooner. The findings follow the evidence.
- Tell us which estimate would help your next revision, or how you have used one, using the form below.
Your question
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