I created this post using Claude Opus 5.5 to edit a draft entirely written by me. I wrote the vast majority of it in November 2025, and it already had all the calculations below.

Summary

• The cost of offsetting the suffering a diet causes to farmed animals depends a lot on the question being asked. How much money is needed to help each type of farmed animal affected by the diet about as much as the diet harms it? Or how much money is needed to decrease the suffering of farmed animals as much as the diet increases it, regardless of which animals benefit? The cost also depends on the cost-effectiveness estimates used, and on how much they are adjusted for conservatism.
• FarmKind’s Compassion Calculator answers the 1st question. It recommends donating 278 $/person-year to offset the suffering random Western adult omnivores cause to farmed animals. It models conservatively on purpose, as it wants donors to be confident that their donations are enough.
• For the 2nd question, I estimate 2.04 $/person-year for random people in the United States (US) based on Animal Charity Evaluators’ (ACE’s) results, and 0.279 $/person-year based on my own numbers for the suffering caused to farmed animals, and the past cost-effectiveness of the Shrimp Welfare Project’s (SWP’s) Humane Slaughter Initiative (HSI).
• Changing one modelling choice at a time in FarmKind’s spreadsheet shows how much each choice affects the cost. For example, offsetting the suffering of birds raised for meat with cage-free corporate campaigns changes the cost from 278 to 109 $/person-year, and barely requires comparing welfare across species, as almost all birds raised for meat are chickens.
• Which estimate is more useful depends on what a donor wants an offset to do, and on how much margin they want for uncertainty.

Two questions an offset can answer

FarmKind estimates “how much it might cost to help animals as much as the average diet negatively impacts them”, based on the cost-effectiveness of interventions helping each type of animal involved in the production of beef, dairy, pork, poultry meat, eggs, and farmed finfishes and crustaceans. The average diet is “a weighted average of a handful of Western, English-speaking countries” (the US, the United Kingdom, Canada, Ireland, Australia and New Zealand), which “roughly reflect the donors that use FarmKind”. Aidan Alexander and Thom Norman, co-founders of FarmKind, commented they are dealing with offsetting the suffering of different farmed animals in agreement with users’ expectations. Their view is based on conversations they have had with donors, and I do not dispute it.

FarmKind explains its “outputs should be viewed as rough ballpark estimates rather than precise figures”, and that it adds “large discounts for conservatism” for donors to be confident they are donating enough. Its calculator says “there is a significant margin of error in these kinds of calculations, which we have accounted for by modelling conservatively”. In its spreadsheet, it applies “Adjustment[s] for conservatism”, explaining that “These estimates are necessarily highly uncertain and so we want to err on the side of conservatism as we’d rather people end up helping more than they intend than that people think they’ve fully offset their consumption when they haven’t”.

The 2nd question pools the suffering of all the animals involved, and offsets it with whatever decreases suffering most cost-effectively. Unless the animals helped are of the same species as the ones harmed, this requires comparing welfare across species.

The 2 questions suit donors with different goals. Donors who want the types of animals affected by their diet to be the ones helped may prefer the 1st. Donors who want to decrease the suffering of farmed animals as much as possible per $ may prefer the 2nd.

How each modelling choice changes the cost

Both FarmKind’s calculator and ACE’s estimates rely on Ambitious Impact’s (AIM’s) suffering-adjusted days (SADs). So I think the difference between 278 and 2.04 $/person-year mostly comes from other modelling choices. I started from FarmKind’s spreadsheet, and changed one modelling choice at a time. The table summarises the results.

The list below explains each change, numbered as in the table:

1. Offsetting the suffering of birds raised for meat with cage-free corporate campaigns. FarmKind estimates the money per person-year needed to offset the suffering of birds raised for meat (chickens and turkeys) is 65.2 (= 182/2.79) times that needed to offset the suffering of laying hens. ACE estimates the suffering of farmed animals caused by the consumption of poultry meat in the US is 4.64 (= 0.0483/0.0104) times that caused by the consumption of eggs there, and I get a ratio of 2.99 (= -0.302/(-0.101)). Based on ACE’s ratio, and FarmKind’s estimate of the cost-effectiveness of cage-free corporate campaigns, offsetting the suffering of birds raised for meat with these campaigns requires 12.9 $/person-year (= 4.64*2.79) instead of 182 $/person-year, 169 $/person-year (= 182 - 12.9) less. So the overall cost becomes 109 $/person-year (= 278 - 169).
2. Using ACE’s cost-effectiveness estimates for chicken welfare corporate campaigns. FarmKind considers cage-free and broiler welfare corporate campaigns help 1.17 (= 1/0.854) and 0.885 (= 1/1.13) chickens per $, and describes its estimates as “conservative”. These are 10.6 % (= 1.17/11) and 1.92 % (= 0.885/46) of ACE’s estimates for The Humane League (THL). With ACE’s estimates, the overall cost becomes 97.4 $/person-year.
3. Removing the adjustments for conservatism. Without FarmKind’s adjustments for conservatism, the overall cost becomes 152 $/person-year.
4. Offsetting the suffering of farmed finfishes by decreasing that of laying hens. With changes 1 to 3, the overall cost becomes 50.4 $/person-year, and the money per person-year needed to offset the suffering of farmed finfishes is 321 (= 38.2/0.119) times that needed to offset the suffering of laying hens. ACE estimates the suffering of farmed animals caused by the consumption of finfishes in the US is 16.6 % (= 0.00173/0.0104) of that caused by the consumption of eggs there, and I get a ratio of 17.9 (= -1.81/(-0.101)). Based on ACE’s ratio, offsetting the suffering of farmed finfishes by decreasing that of laying hens requires 0.0198 $/person-year (= 0.166*0.119) instead of 38.2 $/person-year. So the overall cost with changes 1 to 4 becomes 12.2 $/person-year (= 50.4 - 38.2). This change requires comparing welfare across species.

Decreasing suffering as cost-effectively as possible

For the 2nd question, I estimate 2.04 $/person-year (= 138/67.5) for random people in the US from the ratio between:

• Effects on farmed animals of 138 SADs per person-year (= 0.126*3*365.25) for the food consumption of random people in the US. I got this based on the estimate from ACE’s 2025 meal replacement model of 0.126 SADs per meal, and an assumption of 3 meals per person-day.
• Decrease in the suffering caused to farmed animals of 67.5 SADs per $. I got this from a weighted mean of ACE’s estimates for the organisations they assessed and recommended in 2025, giving the same weight to each organisation, and to each program within a given organisation. I would prefer to use the cost-effectiveness of ACE’s Recommended Charity Fund, but I would be surprised if this meaningfully changed the result.

I also calculate donating 0.106 $/person-year to SWP is enough to offset the suffering food consumption globally causes to farmed animals, assuming SWP is as cost-effective as HSI has been. ACE estimates the food consumption of a random person in the US causes 2.63 (= 0.126/0.0479) times as much suffering to farmed animals as that of a random person globally. So I estimate donating 0.279 $/person-year (= 0.106*2.63) to SWP is enough to offset the suffering the food consumption of random people in the US causes to farmed animals. This is lower than the estimate based on ACE’s results mainly because I think ACE greatly underestimates the intensity of excruciating pain, and therefore how much HSI increases the welfare of shrimps. ACE assumes 7.06 h of “awareness of Pain is likely to be present most of the time” (hurtful pain) is as painful as 1 h of “severe burning in large areas of the body, dismemberment, or extreme torture” (excruciating pain).

All these estimates are very uncertain. Donors who want a margin for the uncertainty can donate more than the estimates above, which is the reasoning behind FarmKind’s conservative modelling. My estimates are for the US, whereas FarmKind’s is a weighted mean for 6 Western countries, and I have not adjusted for this.

Acknowledgements

Thanks to Aidan Alexander, Aidan Whitfield, Anonymous Person, Kevin Xia, Thom Norman, and Toby Tremlett for feedback on the draft. Aidan Alexander clarified he only skimmed the summary of the draft from November 2025. The views expressed in the post are my own.