Methodology

Suffering-Adjusted Days

The atlas measures suffering in Suffering-Adjusted Days (SADs), the metric Ambitious Impact (AIM, formerly Charity Entrepreneurship) uses to compare animal-welfare problems and charities. AIM defines SADs as the “amount of days in a certain type of pain, conditional on sentience and welfare range”. The reference point is human: one day of disabling pain experienced by one person counts as one SAD.

SADs rest on the Welfare Footprint Institute’s way of describing experiences. Rather than giving an animal one welfare score, Welfare Footprint estimates how long it spends in four intensities of negative experience: annoying, hurtful, disabling and excruciating. “Pain” covers any felt negative state, so fear, hunger, heat stress and frustrated natural behaviour count as well as injuries. Each welfare problem (keel-bone fractures in hens, lameness in broilers, crowding in shrimp ponds) is described by how long it lasts, how many animals it affects and how likely each intensity is. Problems are added together, and because they overlap an animal can accumulate more than 24 hours of pain in a day.

This site uses AIM’s SADs v.2 (2026) inputs, downloaded on 15 October 2026. There are several incompatible versions of SADs, so figures computed with different versions (AIM’s 2024, 2025 and 2026 models, and Animal Charity Evaluators’ own 2025 adaptation) should not be compared directly.

The model

For each group of animals the atlas adds suffering during life to suffering while dying:

“Pain-days” are disabling-equivalent days: a day of disabling pain counts as one, and the other intensities are converted with the weights below. Multiplying by the welfare range (how intense the animal’s experiences can be, relative to a human’s) and by the probability that it is sentient turns them into SADs, exactly as AIM does. Deaths are animals killed by people (slaughter, capture or culling) for farmed, caught and laboratory animals, and deaths from all causes, mostly natural, for wild animals, managed honeybees, and dogs and cats.

AIM’s own headline since April 2026 is the four intensities reported separately; it keeps the single weighted total “for information only”. The atlas has to add up 30 groups, so its rankings use the weighted total. Species pages also show the four intensities separately wherever there is a pain-hour model: the whole total for the 13 modelled, borrowed or dying-only groups, and the dying term only for the 17 groups converted from a welfare level, whose life term cannot be split. The other measures on the Atlas are simpler: animals alive now and killed per year are counts, and the welfare-adjusted population is alive × P(sentience) × welfare range.

Where the pain-hours come from

• Laying hens and broiler chickens: AIM’s v.2 models, built mostly on Welfare Footprint Institute analyses (570 of 600 and 836 of 872 intensity estimates).
• Pigs and silkworms: AIM’s own v.2 models (AIM staff estimates using the Welfare Footprint method). Pigs blend market pigs and breeding sows.
• Farmed shrimp: AIM’s v.2 model, built on Rethink Priorities’ 2024 shrimp welfare analysis of the grow-out stage.
• Farmed fish: AIM’s salmon model without the salmon-only problems, which is how AIM itself estimates other farmed fish; dying adds the Welfare Footprint Institute’s 2025 study of trout dying by air asphyxia.
• Borrowed values: turkeys and ducks use broiler values, crabs and crayfish use shrimp values, and farmed insects use silkworm values. These are marked “Borrowed pain model” on their species pages.
• Male chicks: only their deaths are counted, using AIM’s February 2025 quick estimate of one minute of excruciating pain each (AIM’s 2026 models have no chick model).
• Wild-caught fish and crustaceans: only their capture and killing is counted, with dying profiles built for this site (below); their lives are counted with wild animals.
• Everything else has no pain-hour estimate and is converted from a welfare level (below).

All of AIM’s models describe high-income-country systems, and they treat the time spent in pain as a point estimate.

Pain-intensity weights

Because the four intensities are only ranked, they need weights before they can be added. These are the largest judgement call in the metric. AIM’s v.2 weights, derived mostly from human time-trade-off and health-utility studies plus community surveys, count a day of annoying pain as 0.057 disabling days and a day of excruciating pain as about 11. They have moved a lot between versions: AIM’s 2025 model treated excruciating pain as 83 times worse than disabling. You can switch between these sets on the Atlas page:

Switching weights can reorder groups whose suffering is mostly chronic and mild (crowding, barren cages) relative to groups whose suffering is brief and intense (slaughter, boiling). Each species page shows how its total and rank change under every set.

Moral weights

By default the atlas uses Rethink Priorities’ welfare ranges, conditioned on sentience, and their mean, as AIM does. A range that already includes P(sentience) must never be multiplied by it again; we use the sentience-conditioned values and apply P(sentience) separately. The 2024 book Weighing Animal Welfare covers pigs, chickens, carp, shrimp, black soldier flies and octopuses. Honeybees, silkworms, and crabs and crayfish use RP’s 2023 Moral Weight Project values instead, which come from a different mix of models (including a rate-of-experience adjustment the 2024 values lack), so they are not strictly comparable. Where RP estimated neither a species nor its group, we borrow the closest one, marked as a proxy on the species page (wild nematodes borrow the silkworm value).

You can switch to two alternatives on the Atlas page. The results are then labelled SAD-equivalents, because they are no longer AIM’s metric:

• Neuron counts: total neurons relative to a human’s (about 86 billion). A common but contested proxy; RP argue it is a poor measure of welfare capacity on its own.
• Equal weight: every sentient individual counts the same as a human. This shows the raw scale of numbers.

Probability of sentience can be switched off, in which case every group is treated as certainly sentient (SADs conditional on sentience).

Groups without pain-hour data

Most groups, including cattle, sheep, geese, rabbits, fur-farmed, laboratory and companion animals, bees and all wild animals, have no pain-hour estimates. For them the atlas converts the group’s average welfare level (from −100%, as bad as a life can be, to +100%) into pain-days with one constant, fitted on the groups where both measures exist:

The welfare levels are Charity Entrepreneurship’s 2018 Weighted Animal Welfare Index scores. That index scores only 15 kinds of life, so for rabbits, fur-farmed animals, geese, laboratory animals, honeybees, and dogs and cats we scored the same index criteria ourselves; those values are marked as editorial on each species page. The index did not score sheep or goats either: they use Kyle Fish’s 2023 value of −20% (tier 2), which he set equal to the index’s beef-cow score, with our own range. The constant k is the geometric mean of AIM v.2 pain-days ÷ −(welfare level) over the calibration pairs below. Under the default weights a welfare level of −100% corresponds to about eight hours of disabling pain a day. The constant is recomputed for each set of pain weights.

Only pairs whose welfare level is on Charity Entrepreneurship’s scale are used: four from its 2018 index, farmed shrimp from its 2021 shrimp report, and silkworms from a 2024 report by its research training programme (tier 2). Pigs also have both measures, but their welfare level (−40%) is Kyle Fish’s own 2023 estimate rather than a score on the index; adding them would raise the constant by about 8%.

This keeps every group in one unit, but these estimates are much weaker. The calibration rests on six farmed-animal comparisons, three of them chickens; the welfare index scores distance from an ideal life rather than time in pain; and a welfare level is a net figure, so for groups with mixed lives good experiences partly offset suffering, and a group whose average is above zero gets no SADs at all. Dogs and cats are therefore split into owned, free-roaming and shelter sub-populations, each converted on its own, so that pets with good lives do not cancel out strays. On the Atlas these groups are drawn with open markers.

Suffering while dying

For modelled groups, and the farmed groups that borrow a modelled species’ values, AIM’s end-of-life problems (catching or depopulation, transport, lairage, and slaughter until loss of consciousness) are moved out of the life term into the dying term, so nothing is counted twice. Deaths on the farm before slaughter are already part of the life term. Five farmed groups with no pain-hour data borrow an AIM end-of-life profile as well: geese and rabbits use the broiler one, and beef cattle, dairy cows, and sheep and goats the pig one (transport and stunning).

Fur-farmed, laboratory and companion animals, managed honeybees, wild-caught fish and crustaceans, and all wild groups have a dying profile built for this site: a mix of causes of death, each weighted by its share of deaths and given a duration and intensity split. Wild animals mostly die young, by predation, starvation, exposure or disease; the profiles use mortality studies and the Welfare Footprint Institute’s pain estimates for these causes, and count only the final phase of dying, so long hunger or illness before it stays in the life estimate. Wild-caught fish and crustaceans are profiled by fishing gear (crowding in purse seines, crushing in trawls, hours in gillnets, then asphyxia, ice or live gutting) and are counted only while being caught and killed, because their lives are counted with wild animals. Most of the shares and durations are our own documented estimates, and the species page of each of these groups lists the causes behind its profile.

Uncertainty

Intervals come from a seeded Monte Carlo simulation of 1,500 draws per group. Counts, welfare ranges, P(sentience), welfare levels and the time spent in pain are each drawn from a distribution whose 5th, 50th and 95th percentiles match the published low, central and high values. AIM varies only welfare range and sentience; we also vary pain-hours, the conversion constant (×/÷2.5) and dying. Pain-hours vary by a factor of about two either way for modelled groups (for laying hens the low end is the cage-free value) and three to five for borrowed ones, our assumption. AIM’s end-of-life profiles, and those borrowed from them, vary ×/÷3. The dying profiles built for this site and the groups counted only while dying are drawn between their own low and high values, which are often much wider: from about ÷2 and ×2.4 for wild mammals to ÷16 and ×15 for managed honeybees. Inputs are drawn independently, which probably understates the uncertainty. The pain weights are not varied: they are a choice you make with the selector.

SADs averted per dollar

Where one has been published, the intervention pipeline shows the estimated SADs averted per dollar: from AIM research reports, Animal Charity Evaluators’ reviews and their linked cost-effectiveness sheets, and a few independent analyses (tier 2). Each figure is labelled with its evaluator, year and SAD version, and none has been recomputed with the v.2 inputs used elsewhere on this site. The versions differ a lot: ACE’s 2025 per-meal and per-shrimp values are 20 or more times lower than its 2024 ones, so 2024 and 2025 figures for similar programmes are not comparable. Where an evaluator’s review text and its linked sheet disagree, we use the sheet.

AIM’s current bar for a promising animal-welfare idea is over 12 SADs averted per dollar; its late-2024 research round used about 30, and a 2025 round with climate co-benefits used 8. There is no accepted conversion between SADs and DALYs: AIM sets its animal and human bars separately, and they must not be read as an exchange rate. SADs never credit positive experiences, so an intervention that reduces the number of animals is credited with all the suffering they would have had and nothing for good experiences forgone.

The “Burden vs. attention” chart compares each problem’s size with its funding (SADs per year per dollar a year). That is not the cost-effectiveness of any intervention.

Source hierarchy

Every number links to its sources, and each source carries a tier:

• Tier 1 Rethink Priorities research (including RP reports posted to the EA Forum), the Welfare Footprint Institute, Ambitious Impact (Charity Entrepreneurship), FAO/FAOSTAT, fishcount.org.uk, Our World in Data, peer-reviewed papers, Open Philanthropy (Coefficient Giving), Animal Charity Evaluators and Founders Pledge.
• Tier 2 EA Forum posts by other authors, and similar community research. Useful, often the only source on a question, but weighted below tier 1.
• Tier 3 Organisation websites, news, blogs, and our own documented assumptions.

When sources disagree, the highest-tier source sets the central value and the others widen the range. Numbers we could not check against a primary source are flagged as unverified in the data files.

Caveats that matter most

• Wild animal numbers dominate everything once invertebrates are included, and their SADs come from the welfare-level conversion, not from pain data. Treat any total that includes wild animals as illustrative. The life term also leaves out fish larvae and tadpoles, although they make up most wild deaths.
• Some of the largest human-caused totals rest on our own welfare levels. Managed honeybees rank first under the default assumptions because there are about 3 trillion of them; their welfare level (−14%, with a range from −45% to +15%) is our scoring of Charity Entrepreneurship’s criteria, not a published estimate.
• The pain weights are contested and have changed sharply between AIM’s versions. Read rankings together with the weight selector.
• Only hens and broilers rest mainly on Welfare Footprint analyses. Pigs, salmon and silkworms are AIM staff estimates, shrimp come from Rethink Priorities, and farmed fish other than salmon have no model of their own.
• Sleep is handled inconsistently in AIM’s models: the pig model subtracts eight hours a day of sleep, the silkworm model discounts sleep for one issue (hunger and thirst), and the hen, broiler, salmon and shrimp models do not. Per-day comparisons across species are affected.
• Welfare ranges for invertebrates rest on a small evidence base. RP’s own 5th–95th percentile intervals run from 0.001 or less up to about 1, at least three orders of magnitude, and the 5th percentile is zero for bees, silkworms, and crabs and crayfish.
• Counts of fish, shrimp and insects are estimated from tonnage divided by average body weight, and published ranges are wide.
• The model is additive and linear: it assumes a day of suffering in one animal counts the same wherever it happens, and that suffering in different animals can be added up. Some ethical views reject this.
• Funding figures in the burden-vs-attention chart are rough, combine different years, and leave out government spending.
• AIM itself warns that “SADs introduce a large amount of uncertainty and subjective judgement calls and so shouldn’t be used unless necessary.”

Default values

Every default the model uses, under AIM v.2 weights. The same values are in the downloadable data.

Corrections and contributions

The data lives in plain JSON files in this site’s repository, built from the research files by a short script. If you find a better source, a mistake, or an intervention we missed, open an issue or pull request with the source attached.