Animal Charity Evaluators (ACE), an organization that evaluates animal advocacy initiatives, completed a year-long trial of a four-day, 32-hour workweek while keeping salaries unchanged. All the main success criteria were met or exceeded, and the board approved making the 32-hour week the permanent default. The organization shared its findings publicly, arguing that the model could work elsewhere with the right preparation.
The decision to test the policy was based on ACE’s guiding principles of evidence, doing the most good and compassion. After several staff members raised the same idea within a few months, the organization spent more than 40 hours on research.
The evidence was consistent and more positive than expected: the UK’s national pilot, one of the largest of its kind, recorded a 71% reduction in burnout and a 65% reduction in sick days among nearly 3,000 employees, while 92% of participating companies continued the policy after the trial ended. Research compiled by 4 Day Week Global reports similar findings.
There was also a practical incentive. The 2024 compensation review showed that ACE’s leadership salaries were 16–24% below comparable levels in the movement, and the budget did not allow for raises to close the gap. A 32-hour week with full pay effectively amounts to a pay raise. According to research by 4 Day Week Global, most employees would choose a four-day week over a comparable pay increase: 32.8% said they would need 26–50% more money to return to a five-day week, 12.2% would need more than 50%, and 13.8% said no amount would persuade them to return to five days.
Preparation for the trial took nearly nine months, in collaboration with Dr. Alex Soojung-Kim Pang.
Each team reviewed its meetings and daily work to remove anything that was not critical to the mission, while the organization invested in AI tools and automation. Four basic rules were established: accountability for achieving in 32 hours what had previously been done in 40, uninterrupted service to stakeholders, flexibility when critical work required more hours, and transparency about anything that was not working. All staff participated, and the offices closed completely on Fridays.
The results were clear. Of the 21 key goals, 19 were met, as were 10 of the 11 performance indicators. Tasks completed on Asana increased by 18.4% compared with the previous year, while the share of overdue tasks stayed at around 2%, well below the 5% threshold. Fundraising also improved: the Recommended Charity Fund exceeded its budget by 15% and the previous year’s total by 11.5%, while Movement Grants exceeded their budget by 66% and the previous year’s total by 78.6%.
The staff experience score reached 8.08 out of 10, above the target of 7.5. Quarterly well-being surveys, which compared each employee with their individual baseline before the trial, showed an 11.1% reduction in burnout, a 12.9% reduction in the frequency of high work stress and a 6.8% reduction in overall work stress. Efficiency increased by 12.3%, work-life balance by 11.8% and satisfaction with pay by 8.9%. All but one staff member voted to continue, and no departures were linked to the trial.
ACE notes that some gains may also have come from the use of AI or other changes, so performance cannot be attributed solely to the shorter week.
An unexpected benefit was that some of the extra time went toward helping animals. Without any requirement to do so, several staff members used their free time to volunteer: one person wrote and published a book on AI and animal advocacy, two volunteered with UK Voters for Animals, helping it develop into a funded organization with a paid coordinator, and another became chair of the board of an animal advocacy organization in Canada. Others contributed to training programs, technical support for small nonprofits and art inspired by animals.
Based on the lessons learned, the policy became more flexible. Teams can now distribute their 32 hours differently: over four days, evenly across five days or with a partial Friday, while Fridays remain free of internal meetings for everyone. “Peak periods” of up to eight weeks a year were also introduced, during which a team can temporarily return to 40 hours — averaging out to roughly a 33-hour week. Compensatory time off for weeks of 33–40 hours was abolished, and public holidays falling on a Friday or Saturday are now observed on Friday, avoiding consecutive short weeks.
ACE published the results as part of its commitment to transparency. The direct cost of the trial was almost zero, while it provided a staff retention benefit comparable to a substantial pay raise at a time when the budget could not support one.
The findings are consistent with the largest controlled study of the four-day week, published in Nature Human Behaviour in July 2025, which followed 2,896 employees at 141 companies in six countries for six months, recording reduced burnout and improved health without a loss of productivity. The organization encourages others to seriously consider similar trials, noting that the model that worked at ACE may not suit every organization, but that with proper preparation it is possible to do more critical work in less time while giving the team a better life.
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