For most of the last century, the case for shorter hours was theoretical. It is not theoretical anymore. Over the past decade, hundreds of companies and several governments have run the experiment directly: cut the hours, keep the pay, and measure what happens to output. The results are remarkably consistent.

What does the headline evidence show?

Start with the largest pilot in history. In 2022, sixty-one companies and around 2,900 workers in the UK ran a six-month four-day week, organised with independent researchers from Boston College and Cambridge keeping score.1 The rule was 100-80-100: full pay, eighty percent of the hours, output held at one hundred percent. Revenue across the companies stayed broadly flat and rose for some. Seventy-one percent of employees reported less burnout, sick days dropped sharply, and stress, anxiety, and sleep all improved. When the trial ended, ninety-two percent of the companies kept the four-day week, and eighteen made it permanent.2 A year on, nearly nine in ten were still running it, and the wellbeing gains had held. The lead researcher noted this was “not a novelty effect.”3

Can it scale beyond willing volunteers?

It already has. Iceland ran the largest shorter-hours trial in the world from 2015 to 2019, covering more than 2,500 workers, over one percent of the national workforce, including hospitals, preschools, and social services. Hours fell from forty to around thirty-five or thirty-six with no cut in pay. Productivity and service quality held steady or improved across most workplaces.4 Unions then negotiated shorter hours permanently, and today around eighty-six percent of Iceland’s workforce works shorter hours or has won the right to.

Is the evidence actually rigorous?

The most rigorous evidence is now peer-reviewed. A 2025 study in Nature Human Behaviour followed about 2,900 workers across 141 organisations in six countries through a six-month four-day week and found significant improvements in burnout, mental health, and job satisfaction.5 This is no longer a campaign talking point. It is published science.

What are the honest caveats?

Two matter. First, companies self-select into these trials, which likely biases the sample toward organisations already supportive of flexibility, and wellbeing is easier to measure objectively than productivity.6 Second, the model strains where the job is defined by physical presence and coverage. A six-hour-day experiment at a Swedish care home improved nurse wellbeing but required hiring about seventeen extra staff to maintain coverage.7 Shorter hours are not free in every setting.

What is the real lesson?

How the successful trials did it is the tell. They did not ask everyone to try harder. They capped meetings, protected focus time, and moved status updates to written channels, then cut the hours.8 They eliminated the fat first. The four-day week works not because four is a magic number, but because preparing for it forces an organisation to delete the low-value work it had simply never questioned. The hours fall because the waste does. That is a result any individual can borrow, whether or not their employer ever runs a pilot.

Frequently asked questions

Does the four-day week actually work?

The evidence is consistent and now peer-reviewed. Across hundreds of companies and thousands of workers, output and revenue held broadly steady while burnout, stress, and sick days fell, and the large majority of companies kept the four-day week after their trials ended.

What is the 100-80-100 model?

It is the rule behind most four-day-week trials: one hundred percent of pay, eighty percent of the hours, in exchange for a commitment to maintain one hundred percent of output. The reduced hours are a genuine cut, not a compressed five days.

Is there rigorous proof the four-day week works?

Yes. A 2025 study in Nature Human Behaviour followed about 2,900 workers across 141 organisations in six countries and found significant improvements in burnout, mental health, and job satisfaction over a six-month four-day week.

About the author

Tom Goodwin

Tom Goodwin is the author of Don’t Work Harder, a book about taking the time AI gives back as time rather than more work. He is a co-founder of GAMEPLAN and writes on productivity, technology, and the economics of the working week.

Footnotes

Footnotes

  1. Autonomy and 4 Day Week Global, The Results Are In: The UK’s Four-Day Week Pilot (February 2023): 61 companies, about 2,900 workers, on the 100-80-100 model, with research by Boston College and Cambridge. ↩

  2. Autonomy (2023): revenue broadly stable, a 65 percent reduction in sick days, 71 percent reporting reduced burnout, and 56 of 61 companies (92 percent) continuing, 18 permanently. ↩

  3. NPR, “These companies tried a 4-day workweek” (February 2024): around 89 percent still operating a year on; Juliet Schor describes the results as “not a novelty effect.” ↩

  4. Autonomy and Alda, Going Public: Iceland’s Journey to a Shorter Working Week (2021): trials 2015 to 2019, more than 2,500 workers, about 86 percent of the workforce subsequently on shorter hours or entitled to them. ↩

  5. Wen Fan, Juliet Schor, et al., Nature Human Behaviour (2025): about 2,900 workers across 141 organisations in six countries, with significant wellbeing improvements. ↩

  6. APA Monitor, “The rise of the 4-day workweek” (January 2025): companies self-select into trials, and productivity is harder to measure objectively than wellbeing. ↩

  7. Reporting on the Svartedalens care-home trial, Gothenburg: improved nurse wellbeing but about 17 additional staff hired to maintain coverage. ↩

  8. 4 Day Week Global trial design and NPR (2024): companies trimmed meetings, blocked focus time, and batched email before reducing hours. ↩