The most-cited test ran in Britain in 2022: sixty-one companies, roughly 2,900 workers, six months of a four-day week with no cut in pay. When it ended, fifty-six of the sixty-one companies kept the policy, and reported revenue that held broadly steady while resignations and sick days fell. The results were reported widely by Reuters and the BBC, and they anchor nearly every four-day week argument since.
What were the pilots, exactly?
The British trial was organized by the advocacy group 4 Day Week Global with researchers at Boston College and Cambridge, using a simple bargain: employees work 80 percent of the hours for 100 percent of pay, in exchange for a commitment to deliver 100 percent of output. Participating companies spanned restaurants, banks, care providers and software firms.
Related trials have since run elsewhere — among them a South African and an Australian-New Zealand cohort organized on the same model, and public-sector experiments in Belgium, Iceland and Japan's government bureaucracy. Iceland's earlier public-sector reductions in working hours, begun after union negotiations in 2015 and 2017, were followed by reports of maintained or improved productivity and are often described as having made shorter hours the norm for a large share of Icelandic workers.
What did the data show?
The headline numbers from the British pilot, as reported by the researchers and covered by Reuters:
- 92 percent of companies continued with the four-day week after the trial, some permanently.
- Revenue stayed broadly flat during the pilot relative to comparable periods, and rose for companies weighted by size.
- Sick days and staff turnover fell — companies reported measurably fewer days lost.
- Self-reported stress and burnout declined, and scores on work-life balance and sleep quality improved.
How did companies make it fit?
Not by squeezing the same work into fewer hours through heroics, mostly, but by changing how work is arranged. Common moves reported by participants included shorter meetings with default agendas, clearer prioritization, focused work blocks without interruption, and in some operations — the harder cases — staggered scheduling so coverage stayed continuous across five business days.
The companies that struggled were the ones whose hours are the product: hospitality, healthcare, manufacturing lines. Some participated anyway through shift redesign and additional hiring, which raises the honest caveat that the model travels best where output is not measured in clock time.
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What are the caveats?
Worth stating plainly, because enthusiasts tend to skip them.
Selection. Companies that volunteer for a four-day week pilot are, by definition, unusually open to the idea and likely to have engaged leadership. Skeptical firms did not enroll, so the sample tells you about the willing.
Novelty and observation. Six months is short, and everyone knew a study was underway. Some of the productivity finding may reflect attention, not the calendar.
Self-reporting. Revenue figures were supplied by the companies themselves, and wellbeing outcomes were survey-based.
Job type. The evidence is thinnest exactly where hours are least flexible — shift work, care work, small retail — which is also where many readers of a piece like this work.
Did anything not work?
Some firms withdrew or returned to five days, reporting that client expectations or workload could not be reshaped. And workers' experiences varied: surveys found a minority of participants felt compressed or pressured by the intensity of four longer or denser days. A shorter week with the same pressure is a schedule change, not a life change.
What about workers whose hours cannot compress?
The honest limit of the pilots is that they mostly tested people whose output is a deliverable. A nurse, a line cook or a bus driver cannot compress care, cooking or driving into fewer hours; for them a four-day week means hiring more colleagues to cover the fifth day, not reorganizing meetings. That is a different and more expensive proposition, and the trials offered little evidence on it.
The compressed-schedule variant — full-time hours across four longer days — travels somewhat better into shift work, and it is what Belgium legislated as a worker's right to request. But it changes the shape of a week without shortening it, and workers with children or caregiving often find four ten-hour days harder, not easier. The evidence for reduced hours is strong where work is flexible; the evidence for flexibility where work is not remains mostly theoretical.
What is happening since?
Legislatures have nibbled. Maryland legislators proposed tax incentives for employers moving to four-day weeks; a California bill to shorten the standard workweek to thirty-two hours stalled. Belgium gave workers the right to request a compressed four-day arrangement of full-time hours across four days. None of this amounts to a national shift, and most American workers' weeks are untouched by any of it.
Meanwhile some well-known companies adopted or trialed shorter weeks and publicized the results, which has kept the idea in boardroom conversation even where legislation has not moved.
What is the fair summary?
That the four-day week is not a fantasy — serious trials with real firms found maintained output and improved wellbeing — and that it is not yet a proven universal. The strongest claim the evidence supports is conditional: in knowledge-work settings with willing management and deliberate redesign, the same work fit into less time, and people were healthier for it.
For an individual workplace asking the question, the pilots' real lesson is methodological more than ideological. Define output clearly. Cut the low-value work. Run a defined trial with an exit. That is how sixty-one British companies found out, and it is how the next ones will too.