UK Four-Day Week Trial Results: 92% of Companies Keep Shorter Hours After Landmark Experiment

The results are in from the world's largest four-day working week trial, and they represent a watershed moment for the future of work in the UK. Between June and December 2023, 61 British companies employing 2,900 workers tested whether employees could work four days a week with no loss of pay—and the outcomes have exceeded even optimistic expectations.

According to findings published in February 2024 by researchers at Cambridge University, Boston College, and the think tank Autonomy, 92% of participating companies have chosen to continue the four-day week after the trial ended. Eighteen organisations made the change permanent immediately, while the majority extended the trial or committed to ongoing implementation. Only a handful returned to a five-day schedule.

The business case: revenue stable, costs down

Perhaps the most striking finding for employers is that shorter working weeks did not harm the bottom line. Company revenue remained broadly stable across the trial period, rising 1.4% on average when compared to similar periods in previous years. Given that this trial took place during a period of economic uncertainty and rising costs, maintaining revenue while reducing working hours represents a significant achievement.

The financial benefits extended beyond revenue. Companies reported a 57% reduction in staff turnover compared to the same period in prior years, saving substantial recruitment and training costs. Sick days fell by 65%, reducing absence-related productivity losses. Several business leaders noted that the four-day week had become a powerful recruitment tool, allowing them to attract higher-quality candidates in competitive labour markets without increasing salaries.

"We were sceptical at first," said one participating CEO from a Cambridge-based marketing firm. "But the data is undeniable. Our revenue is up, our team is happier and healthier, and we've had zero resignations since the trial started. We're never going back to five days."

The employee experience: less burnout, better health

For workers, the results were transformative. Stress, burnout, and fatigue all fell significantly during the trial. Employees reported improvements across every measure of physical and mental health tracked by researchers, including sleep quality, energy levels, and overall life satisfaction.

The extra day off provided time for rest, exercise, family commitments, and personal projects that had previously been squeezed into evenings and weekends. Parents reported less guilt about childcare and more quality time with children. Many employees used the time to pursue education, volunteering, or creative hobbies that improved their overall wellbeing and, in some cases, brought new skills back to their jobs.

Critically, these improvements did not come at the cost of productivity. Researchers found that employees worked more efficiently during their four days, with better focus and fewer distractions. The knowledge that they had a three-day weekend every week created a psychological incentive to complete work within the condensed timeframe, reducing time-wasting and improving prioritisation.

How companies made it work

The trial included businesses from diverse sectors—professional services, technology, marketing, healthcare, construction, hospitality, and retail—demonstrating that the four-day week is not limited to office-based knowledge work.

Most companies adopted the '100-80-100' model: 100% of pay for 80% of the time, in exchange for a commitment to 100% productivity. In practice, this meant different things for different organisations. Some reduced total weekly hours from 40 to 32, while others condensed the same hours into four longer days. Office-based businesses typically closed on Fridays, while customer-facing operations used staggered rotas to maintain service levels.

Implementation required careful planning. Companies streamlined meetings, reduced email volume, and eliminated low-value tasks. Several organisations reported that the process of preparing for the four-day week forced them to identify inefficiencies they had tolerated for years. "We realised we were spending hours in meetings that could have been emails, and doing busywork that added no value," said one operations manager. "The four-day week made us ruthlessly prioritise what actually mattered."

Technology also played a role. Businesses invested in better project management tools, asynchronous communication platforms, and automation to reduce manual workloads. Some introduced 'focus time' policies, blocking out periods where employees could work without interruptions.

The challenges and limitations

Not every business found the transition easy. Customer-facing industries like retail and hospitality faced logistical challenges in maintaining service levels with reduced staff hours. Some solved this with staggered schedules, while others found the model incompatible with their operating requirements and withdrew from the trial.

Manufacturing and 24/7 operations also faced difficulties. Shift-based work does not easily compress into four days, and some businesses struggled to maintain output without hiring additional staff. However, a few manufacturing participants succeeded by rotating four-day schedules across teams, ensuring continuous production while giving each employee a three-day weekend.

Smaller businesses with tight margins and limited staff found it harder to absorb the transition costs and operational disruption. Several reported that while they supported the principle, they lacked the resources to implement it effectively without external support or phased adoption.

There were also concerns about workload intensity. Some employees reported that four-day weeks felt more pressured, with less flexibility to manage unexpected tasks or personal needs during working hours. A minority preferred the traditional five-day structure, valuing the ability to spread work more evenly across the week.

The economic and social implications

The trial's success has reignited debate about the future of work in the UK. Advocates argue that the four-day week represents a long-overdue update to working patterns established during the industrial revolution, when the five-day, 40-hour week became standard in the mid-20th century. They point out that productivity has increased dramatically since then, yet working hours have barely changed.

Economists note that shorter working weeks could have broader benefits. Reduced burnout and better work-life balance may improve public health, lowering NHS costs. More time for family and community could strengthen social cohesion. Increased leisure time could boost spending in hospitality, culture, and recreation sectors.

Environmental benefits are also possible. Fewer commuting days mean lower carbon emissions, reduced road congestion, and less pressure on public transport. Some trial participants reported energy savings from closing offices one day per week.

However, critics warn that the four-day week may exacerbate inequality. High-skilled, well-paid office workers are far more likely to benefit than low-paid, shift-based, or gig economy workers whose jobs do not easily accommodate flexible schedules. There is a risk that the four-day week becomes a perk for the privileged, widening the gap between secure, well-compensated employment and precarious work.

What happens next?

The trial results have prompted calls for government support to encourage wider adoption. Some campaigners want tax incentives or grants to help small businesses transition. Others argue for a gradual reduction in the legal definition of full-time work, following the path of countries like Iceland, which successfully piloted shorter weeks across the public sector.

Several UK businesses outside the trial have already announced plans to adopt four-day weeks in 2024, citing the trial's findings as evidence that the model works. Recruitment platforms report a surge in job listings advertising four-day weeks, and surveys show that a significant majority of workers would consider changing jobs for a shorter working week.

However, widespread adoption faces obstacles. Many employers remain sceptical, particularly in sectors where the model is harder to implement. There are concerns about competitiveness, especially for businesses operating internationally in markets where five or six-day weeks are standard. Trade unions have called for four-day weeks to be negotiated collectively rather than imposed unilaterally, to ensure workers are protected from exploitation or unrealistic productivity demands.

The bottom line

The UK four-day week trial has produced compelling evidence that shorter working weeks can benefit both employers and employees. Revenue remained stable, costs fell, and workers reported dramatic improvements in wellbeing and job satisfaction. For the 92% of companies continuing the policy, the four-day week is not a utopian experiment—it is a practical, evidence-based approach to modern work.

Whether this marks the beginning of a broader shift in UK employment practices remains to be seen. But the trial has demonstrated that the five-day week is not an immutable law of nature. It is a choice, and the evidence now suggests there may be a better one.