Why ACE's Metrics Are Not Grounded in Reality

Animal Charity Evaluators (ACE) is the largest charity evaluator in the animal protection movement. As part of their work, ACE calculates metrics that tell people how many animals their donations help:

ACE Advertisement

At face value, the idea of calculating the impact of animal charities seems promising. After all, if you can save 10x more animals by donating to one charity instead of another, you'd naturally want to donate to the more impactful option.

However, there's a serious issue with this approach: not all forms of charitable work can be quantified.

Take Faunalytics, a charity that manages an online research library (basically an online list of research articles).

In one of their evaluations, ACE calculated the impact of Faunalytics' research library. Their analysis suggests that Faunalytics' research library spared 227,556 animals in a single year—equivalent to 5.9 animals spared per dollar spent on the library.

These numbers sound amazing, but there's a key problem: they have no grounding in reality. The idea that you can calculate how many animals were "spared" by an online list of research articles is complete nonsense. It is impossible to know how many animals, if any, were spared by this work.

So how did ACE calculate these metrics? Simple. ACE assumed that each subscriber to Faunalytics' research library resulted in 42 animals being spared, then multiplied this by the total number of subscribers.

The Biggest Assumption Wins

The core problem with ACE's metrics is that they are based on unverifiable assumptions. As a result, ACE can reach any cost-effectiveness number simply by changing their assumptions (e.g. assuming 500 animals spared per subscriber instead of 42).

And who gets the best assumptions? Well, according to statements from former ACE employees, ACE promotes "organizations run by their friends" and makes decisions that have "absolutely nothing to do with evidence."

This means that many of ACE's metrics may not just be baseless, but also the result of favoritism.

Over 10 Years of Bad Math

The calculations discussed above were created over 10 years ago. Yet even today, ACE continues to produce similarly flawed calculations.

In one of their recent charity assessments, ACE claims that the "Cage-Free Accountability" program shown below "is likely to help 11 egg-laying hens per dollar."

It is implausible that work like this helps multiple animals per dollar. And when ACE publishes baseless metrics like this, it harms not only donors, but also "average" animal charities—who ACE has marketed as 100x less impactful than ACE recommended charities:

LinkedIn Post from ACE

This works great for ACE and their recommended charities—but not for the rest of the animal protection community, which is forced to compete with metrics that are not grounded in reality.

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References

    5.
    ACE Statement Claiming 100x Impact from September 9, 2025

    Key Quote: "The most effective animal charities can be 100x more impactful than the average one! At ACE, we dive deep into research, data, and impact to find the nonprofits that actually help animals the most, so your donations create real, measurable change."

    6.
    ACE's 2025 Review of The Humane League

    Key Quote: "Cage-Free Accountability (U.S., Global, and U.K., for commitments for egg-laying hens). Our CEA indicates that this work is likely to help 11 egg-laying hens per dollar through driving a transition to cage-free systems, equating to 88 Suffering-Adjusted Days (SADs) averted per dollar (range: 17–351)"