A growing number of people do not eat animals, and a smaller but also growing number of people do not eat animal products. This probably has enormous benefits for many animals that would otherwise have been eaten. Being a cage-farmed chicken is probably a terrible kind of existence and it is possible that such a chicken would wish not to exist if it could do so. Moreover, it is probably possible to compare the suffering of different kinds of being, and doing so may help focusing on doing more good, if the calculation is used for decisions on where to invest scarce resources. Finally, not eating animals (or not eating animal products) also makes sense as a simple behavioral rule for someone who is motivated by the wish to avoid causing animal suffering.

However, these claims are very specific, and it is important to pay attention what conclusions follow from what arguments. It also clearly is important to make sure that methods that can be used to derive rational decisions are actually appropriate to the decision at hand. People motivated both by optimization and by reducing suffering need to be rigorous in this respect, otherwise the optimization will not work.

This is a too long introduction for saying that you should not tell people that they should not eat chicken but maybe beef and dairy because Brian Tomasik's suffering calculator chart shows, for example, that eating a kilogram of chicken causes 33.75 times as much suffering as a kilogram of beef.

Not all animals' conditions are equal

Omnizoid states that it is "thoroughly obvious" that you "shouldn’t eat animals in normal circumstances" because "animals undergo cruel, hellish conditions that we’d confidently describe as torture if they were inflicted on a human (or even a dog)", but notes that "not all animals are the same". Omnizoid's point is that not all animals have the same capacity of suffering and not all animals weigh the same, so you need to take this two properties into account to see how much suffering your lunch causes. Omnizoid then uses Brian Tomasik's calculator to derive that "if you get a gallon of milk, that’s only equivalent to confining and tormenting a baby for about 4 and a half hours", and to compare it to other kinds of animal products, noting that "this chart was instrumental in my going vegan. I realized that each time I have a chicken sandwich, animals have to suffer in darkness, feces, filth, and misery for weeks on end. That’s not worth a sandwich, no matter how tasty. But if you are going to eat meat, at least lay off the chicken."

This motivation is noble, and the approach of comparing by calculating is sensible. The behavioral rule that is suggested by Omnizoid, and also by many others who try to reduce animal suffering, respects that there are many people who will not become vegans, but may still be willing to adjust their diet. 

Alas, while it is true that "not all animals are the same", it is also true that not all kinds of farming are the same, and while the sentence "animals undergo cruel, hellish conditions" is true, it lacks a word like "some", "many", "most", or "factory-farmed" before the word "animals", such that you may believe that all kinds of animals live the same hellish lives. 

Tomasik's Calculator Table

Brian Tomasik's motivation for his calculator table reads as follows:

"Animals living on factory farms endure great amounts of suffering, enough that it's generally bad to bring them into existence by creating economic demand for meat. If readers are unconvinced on this point, I recommend the vast collection of literature available online, including "Modern Animal Farming", "What Came Before", and, for a more rigorous survey, reports by the Humane Society of the United States.

Eating certain types of meat may cause more suffering than eating the same amount of another type of meat under otherwise identical circumstances. Below, I investigate how much direct suffering, on average, is caused by creating demand for a kilogram of different types of animal products."

Having a simple tool such as Brian Tomasik's calculator table is very useful for discussing choices and their potential consequences, and a valuable step for making decisions with respect to dietary decisions. But there is a flaw; the "types of animal products" are not differentiated by type of farming, so if I were an alien browsing the internet of Earth and finding this tool, I had to assume that all farmed animals are always and automatically factory-farmed. 

Even if this is true for a large majority of farm animals, the relevant individual decisions are decisions about the next kilogram of meat that will be bought (or not bought). Just as you can choose between chicken and beef, you can often choose between factory-farmed chicken and free-range farming. The way that different animals are farmed should make some difference with respect to ethical judgement. 

Tomasik's table ranks different animals by "Equivalent days of suffering caused per kg demanded", but this comparison is strongly driven by column 5, "Suffering per day of life (beef cows = 1)":

"Column 5 represents my best-guess estimates for how bad life is per day for each of type of farm animal, relative to that animal's intrinsic ability to suffer. That is, differences in cognitive sophistication aren't part of these numbers because they're already counted in Column 4. Rather, Column 5 represents the "badness of quality of life" of the animals. For instance, since I think the suffering of hens in battery cages is perhaps 4 times as intense per day as the suffering of beef cows, I put a "1" in the beef-cow cell and "4" in the egg cell."

This assumes that an average day in the life of all of these animals is a day of suffering. This may be the case in factory farming, but is it necessarily the case for alpine pasture? 

If an average day of a cow in alpine pasture is a good day for the cow, we would need a negative sign.

You can enter a negative sign in the table. However, you'll get an error message, because the whole table is based on the assumption that "Suffering per day of life" is positive. With this assumption, raising the "Average lifespan (days)" (Column 2) increases the "Equivalent days of suffering caused per kg demanded". If this is the case, then people deploring that farmed animals have short lives are mistaken.

Moreover, Tomasik writes, 

"Column 6 is a best-guess estimate of the average pain of slaughter for each animal, expressed in terms of an equivalent number of days of regular life for that animal. For instance, I used "10" as an estimate for broiler chickens, which means I assume that on average, slaughter is as painful as 10 days of pre-slaughter life."

If the animals actually enjoy their life (negative number in column 5), you can still use that column by entering a negative number in column 6; these are the days an animal would forgo if it could avoid being slaughtered. So if we take the numbers in the table for beef and assume that the value for column 5 is -1 (I don't know how to interpret this, though, as this is all relative to beef cow suffering), we need to enter -395 in column 6 to get to zero in column 7.

A different kind of calculator, and what it should be able to compare

To make the calculator better, we would need to replace column 5, "Suffering per day of life (beef cows = 1)", with a column containing "Happiness per day of life (on a scale from 0 to 10, where 0 is purest suffering, and 10 is most extreme happiness)", or something like that; column 6 would also have to be adjusted. (A scale from some negative to some positive number would be a sensible alternative, but happiness research generally seems to use 0-10 scales.) 

I will not try to do that, because I hope that other people already have done so, or are able to do it much faster and better than I could.

If such an adjusted calculator informs decisions, it may motivate some people to only eat animals that are raised under certain circumstances. Would that be a good thing, compared to the existing approach of using the suffering-table argument to tell people not to eat chicken? Probably yes, because it would be motivated by a model that closer to reality (while not being much more complicated). This behavior of deleting some kinds of food from the grocery list would also be similar to what many people seem to be trying already and which is legislated in some polities. For example, 59.7 % of eggs in Germany were "cage-free eggs" in 2023, down by 2.4 percentage points compared to 2018; the share of free-range eggs went up from 18.2 to 22.3 %; organic from 10.9 to 13.5 %; and cage went down from 8.8 to 4.5 % due to a ban with a grandfather clause. That something is similar to what people already do is of course not a quality criterion, but it may be easier to convince people that they should marginally adjust their behavior than telling them that a radical change is absolutely necessary; after all, Brian Tomasik's and Omnizoid's posts had similar motivations, but restricted the choice to a choice between different animals.

Finally, I note that I do not have the impression that the herd of boar in a large outdoor enclosure within a nearby forest seem to be in constant pain. Nor do the chicken in the garden of an acquaintance of mine to be suffering. There is a fence around the chickens, but the part of the garden that is fenced at least does not seem too small. On a "happy animal lives" scale, these are extreme cases, but so is industrial factory farming, and there are many intermediate cases. Quantitatively, factory farming is the much more important case, but decisions matter at the margin. 

I don't know how these garden chicken will die, but given that Tomasik estimates that the "Number of days of life equivalent to pain of death" of a factory-farmed chicken is 10, it may be the case that every one of these chicken will have a very unpleasant end of their live. However, how long would the chicken have to live in my acquaintance's garden to justify this end? And is killing chicken justified if it causes the happy chicken life? You are probably much more of an expert on this than I am. 

Note

I recycled my comment under Omnizoid's post for this. Thanks to @florian-az for valuable feedback.