When a six-month trial in the United Kingdom involving dozens of companies and thousands of employees ended in late 2022, something unusual happened: almost none of the participating companies went back to five days. That single fact has done more to move the four-day workweek from a fringe idea into a genuine corporate policy conversation than a decade of academic argument managed to do on its own. But the headline number, that most companies kept the shorter week, obscures a much messier and more interesting reality underneath it, one involving very different national experiments, industries where the model barely made sense, and open questions about whether the reported productivity gains reflect a genuine efficiency breakthrough or simply harder, more compressed workdays.
A Six-Month Trial That Outlasted Its Deadline
The pilot that put the four-day week on the front pages was coordinated by the nonprofit 4 Day Week Global, the UK-based think tank Autonomy, and researchers from Cambridge University, Oxford University, and Boston College, running from June to December 2022 across 61 companies and roughly 2,900 employees.
Participating organizations spanned marketing agencies, software firms, financial services companies, a fish and chip shop, and a handful of manufacturers, deliberately chosen to test whether the model could stretch beyond the desk-based knowledge work where shorter weeks are easiest to imagine.
What made the trial notable wasn't just its scale but its design: rather than simply asking companies to close on Fridays, researchers required firms to track concrete output metrics before, during, and after the trial, aiming to produce measurable evidence rather than anecdotal enthusiasm.
How the UK's 2022 Pilot Was Actually Structured
The model tested was what organizers call 100:80:100: employees received 100 percent of their previous pay, worked roughly 80 percent of their previous hours, and committed to maintaining 100 percent of their previous output or service level.
Companies were free to implement this however suited their operations, some closing entirely on Fridays, others staggering days off across the week so customer-facing coverage continued, and others compressing the same 40 hours into four longer days rather than genuinely reducing total hours.
This flexibility matters enormously for interpreting the results, because "four-day week" companies in the trial were not testing one single intervention but a family of related but distinct scheduling changes, each with different implications for genuine hour reduction versus rescheduling.
What the UK Trial's Numbers Actually Showed
According to the researchers' final report, 92 percent of the 61 participating companies chose to continue with a four-day week after the trial concluded, and a majority described the change as permanent policy rather than an extended experiment.
Company-reported revenue during the trial period was broadly stable compared to equivalent periods in prior years, with a subset of firms reporting modest revenue growth, though researchers cautioned that six months is too short a window to separate a shorter week's effect from normal business cycle variation.
Employee-reported outcomes were more consistently positive across the sample: resignation rates fell noticeably during the trial period compared to the same months a year earlier, and self-reported measures of burnout, anxiety, and fatigue improved, according to survey data collected by the research team.
Iceland's Earlier and Larger Experiment
Years before the UK trial made headlines, Iceland ran what researchers have described as the largest such experiment relative to population size, involving trials by ReykjavΓk City Council and the Icelandic national government between 2015 and 2019.
The trials eventually covered more than 2,500 workers, around 1 percent of Iceland's entire working population, spanning preschools, offices, social service providers, and hospitals, moving employees from a standard 40-hour week to roughly 35 to 36 hours without any reduction in pay.
A joint 2021 analysis by the UK think tank Autonomy and the Icelandic Association for Sustainable Democracy, Alda, concluded the trials were an "overwhelming success," reporting that productivity and service levels remained the same or improved across the vast majority of participating workplaces.
How Iceland's Results Reshaped Its Labor Market
Unlike the UK pilot, which remained a voluntary, time-limited trial for participating companies, Iceland's results fed directly into subsequent labor negotiations between unions and employers across the country.
Following the trials, Icelandic trade unions negotiated contracts that permanently reduced working hours for a substantial share of the national workforce, and by some estimates roughly 90 percent of Iceland's working population now either works reduced hours or has gained the contractual right to negotiate them.
This distinguishes Iceland's experience from most other country's pilots: rather than remaining a corporate perk offered at individual employers' discretion, reduced hours became embedded in national labor agreements, a structural shift few other four-day week experiments have achieved.
Microsoft Japan and the Early Corporate Experiments
Before either the UK or Iceland trials, Microsoft's Japan subsidiary ran a widely cited one-month experiment in August 2019, closing its offices every Friday while maintaining full pay for its roughly 2,300 employees.
The company reported a productivity increase of about 40 percent measured in sales per employee compared to the same month a year earlier, alongside reductions in electricity consumption and printed pages, figures the company published in its own summary of the trial.
Critics have noted the Microsoft Japan figure is a single company's self-reported, one-month result rather than independently audited research, and August in Japan includes fewer working days generally due to the Obon holiday period, complicating direct year-over-year comparisons, though the trial remains an early and influential data point that helped popularize the idea.
Spain's Government-Subsidized Pilot
Spain took a distinctly different approach starting around 2021 and 2022, with its government funding a pilot program, sometimes referred to under the banner MΓ‘s Bienestar en el Trabajo, that subsidized small and medium-sized companies willing to test a four-day week.
Rather than leaving companies to absorb any transition costs alone, the Spanish government offered to cover a declining share of costs associated with lost productivity during a phased, multi-year trial period, an approach designed specifically to lower the risk for smaller firms that might otherwise be reluctant to experiment.
Early participants included manufacturing and industrial firms alongside typical office-based companies, making Spain's pilot one of the more deliberate attempts to test the model outside the professional services sector where shorter weeks are most intuitive.
Belgium's Different Approach: Compressed, Not Shortened
Belgium's 2022 labor reform is frequently mentioned alongside these pilots but tests a meaningfully different concept: it gives employees the legal right to request compressing their existing full-time hours into four longer days rather than five shorter ones.
Under this law, a worker's total weekly hours generally remain unchanged, meaning the model addresses schedule flexibility and an extra day off rather than the actual reduction in total working time that defines the UK, Iceland, and Spanish trials.
This distinction matters because media coverage frequently blurs compressed workweeks and genuinely shortened workweeks together under the same "four-day week" label, even though the two approaches have very different implications for worker wellbeing, given that a compressed schedule can mean longer, more exhausting individual workdays.
The Industries Where a Four-Day Week Works Well
Across the various pilots, the clearest pattern to emerge is that professional services, technology, marketing, consulting, and other knowledge-work sectors adapted most easily, largely because output in these fields is measured in completed projects and deliverables rather than hours physically staffed on a schedule.
These industries also tend to have relatively high existing rates of meetings and internal coordination overhead, giving companies obvious inefficiencies to cut when facing pressure to preserve output in fewer days, from shortening or eliminating recurring meetings to tightening decision-making processes.
Firms in these sectors also generally have more scheduling flexibility already built into how work gets assigned and reviewed, making a shift to four days a matter of reorganizing workflow rather than fundamentally redesigning how a physical operation runs.
The Industries Where It Struggles
Healthcare, manufacturing with continuous production lines, hospitality, and retail generally reported the greatest difficulty, because these operations require continuous coverage across a full week regardless of any individual employee's schedule, meaning fewer hours per worker generally requires hiring more staff to fill the resulting gaps.
Education presents its own distinct challenge: schools generally cannot simply close an extra day without addressing childcare and instructional-time consequences for students and families, which is part of why most four-day week pilots in education have focused on staff scheduling rather than shortening the school week itself.
Smaller companies across sectors, including in retail and hospitality, that participated in various pilots often reported needing meaningful operational redesign, sometimes including new hires, to maintain coverage, a cost larger firms with more staffing flexibility were better positioned to absorb.
The Work Intensification Question
A persistent criticism of the reported productivity gains is that they may partly reflect work intensification rather than genuine efficiency improvement, meaning employees are simply working harder and with fewer breaks during four days to compress five days' worth of tasks into the same output.
Pilot data lends some support to this concern: several trials reported shorter, more tightly run meetings and reduced time spent on tasks employees themselves described as low-value, changes consistent with genuine efficiency gains but also consistent with employees simply working at a faster, more sustained pace during the hours they are present.
Researchers involved in the UK and Iceland trials have generally argued the self-reported wellbeing improvements, including better sleep and lower stress, suggest genuine efficiency gains rather than pure intensification, since sustained overwork over a six-month period would typically show up as rising rather than falling burnout indicators.
The Self-Selection Bias Problem
Every major four-day week pilot to date has relied on companies volunteering to participate rather than being randomly selected from the broader economy, meaning the sample systematically overrepresents employers already inclined toward flexible, employee-focused management practices.
This self-selection makes it genuinely difficult to know whether the reported success reflects something replicable across typical companies or whether it reflects the fact that companies willing to experiment with radical scheduling changes tend to already have stronger management, clearer processes, and more engaged employees than the average firm.
Economists studying the pilots have generally acknowledged this limitation openly rather than dismissing it, noting that a genuinely representative, randomized national trial, which no country has yet attempted at meaningful scale, would be needed to settle the question more conclusively.
What Employees Actually Reported
Across the UK, Iceland, and Spanish pilots, employee-reported outcomes were the most consistently positive category of results, with participants across multiple independent surveys reporting reduced stress, improved sleep quality, more time for exercise and family, and lower self-reported burnout scores.
Resignation and staff turnover rates fell during trial periods compared to prior-year baselines in several of the pilots, a pattern companies frequently cited as a meaningful, if hard to fully isolate, business benefit alongside any productivity effects, since turnover carries substantial direct recruiting and training costs.
Some employees in lower-paid or hourly roles included in various pilots expressed concern about how a shortened week without proportional wage protection could affect their income if extended beyond a subsidized or voluntary trial, a concern that surfaces more sharply outside the white-collar salaried context where most participating companies operated.
What Employers Actually Reported
Participating employers across the different pilots generally reported that revenue held steady or grew modestly during trial periods, alongside improvements in recruitment, with companies noting a four-day week became a meaningful advantage in attracting job candidates in competitive hiring markets.
A number of companies specifically credited the deadline pressure of maintaining full output in fewer days with forcing overdue process improvements, including trimming unnecessary meetings, adopting clearer task prioritization systems, and reducing lower-value administrative work that had accumulated over time.
Employers in the small minority of cases that reverted to five days generally cited client-facing coverage gaps, difficulty coordinating with partners and vendors still operating on a standard week, or genuine difficulty maintaining output in operationally intensive roles as their reasons for returning to the previous schedule.
Why Six-Month Pilots Don't Prove Long-Term Viability
Nearly all the widely cited pilots ran for six months or less, a window long enough to capture an initial adjustment period and some meaningful behavioral change, but short enough that longer-term risks, including gradual erosion of the productivity gains or slow re-accumulation of the very inefficiencies companies initially cut, remain largely untested.
Business cycle effects are also difficult to separate from scheduling effects in such short windows, since a company's revenue and headcount needs can shift for reasons entirely unrelated to its work schedule within any given six-month period, particularly across pilots that ran during periods of broader economic volatility.
Longer-running natural experiments, such as Iceland's multi-year trials and the ongoing tracking of companies that made the UK pilot permanent, offer somewhat stronger evidence of durability, though even these fall short of the decades-long data available for the standard five-day week that current results are implicitly being compared against.
Where the Movement Stands Now
Following the UK and Icelandic results, additional pilots and policy discussions have spread to countries including Portugal, Germany, South Africa, and the United States, generally following a similar voluntary, company-opt-in structure rather than the kind of binding national mandate Iceland effectively achieved through union negotiation.
4 Day Week Global has continued running structured pilots with participating companies worldwide, building a growing dataset of before-and-after company metrics that, while still non-randomized, represents the largest ongoing body of applied evidence on the model available to researchers and policymakers.
The overall trajectory suggests the four-day week is moving gradually from a curiosity confined to a handful of headline-grabbing trials toward a genuine, if still minority, scheduling option that specific companies and sectors are adopting on their own terms, rather than toward the kind of universal, government-mandated shift some early advocates originally envisioned.
Taken together, the various pilots paint a genuinely more nuanced picture than either the enthusiastic headlines or the skeptical dismissals suggest. The model appears to work well, by the participating companies' own account, in knowledge-work sectors with flexible scheduling and clear output metrics, while remaining a much harder proposition for healthcare, manufacturing, retail, and other operations requiring continuous coverage. Employee wellbeing improvements are the most consistent finding across every major trial, while claims about pure productivity gains remain genuinely contested given self-selection bias and the work intensification question. What began as a fringe idea has, at minimum, generated enough real-world data across enough different countries and industries to move the conversation well past pure speculation, even if the case for universal adoption remains far from settled.
Sources
- 4 Day Week Global β Coordinating body for corporate four-day week pilots worldwide, including the UK 2022 trial.
- Autonomy β UK-based think tank that co-authored the UK and Iceland four-day week trial research reports.
- International Labour Organization β Research on working time trends and reduced-hours policies across countries.
- UK Office for National Statistics β National labor market and productivity data used to contextualize pilot results.
FAQ
Did companies in the UK four-day week pilot actually keep the shorter week?
Yes. Roughly 92 percent of the companies that took part in the 2022 UK pilot run by 4 Day Week Global, Autonomy, and researchers at Cambridge and Oxford chose to continue with a four-day week after the six-month trial ended, and a large share made it a permanent policy.
Did employees in these pilots take a pay cut for working fewer days?
No, in the model most widely tested, known as 100:80:100, employees kept 100 percent of their pay while working roughly 80 percent of their previous hours, in exchange for a commitment to maintain 100 percent of their prior output.
Which industries struggled most with the four-day week?
Sectors that depend on continuous coverage, such as healthcare, manufacturing with shift-based production lines, hospitality, and retail, generally reported the most difficulty implementing a shortened week without hiring additional staff or adjusting service hours.
Is the four-day week just work intensification in disguise?
Critics argue that compressing the same workload into fewer days can increase daily intensity and stress even while total reported hours fall, and some pilot data on rising meeting efficiency and task prioritization supports the idea that intensification played a real role in some of the reported productivity gains.
Do these pilots prove a four-day week works for the whole economy?
Not conclusively, because participating companies volunteered rather than being randomly selected, trials generally lasted only months rather than years, and the pilots concentrated heavily in professional services and knowledge work rather than across the full range of industries and job types in a national economy.
About the Author
We reference 4 Day Week Global, the UK think tank Autonomy, the International Labour Organization, and the UK Office for National Statistics to explain the background and current understanding of this topic.
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