The Four-Day Week: What the Trials Found

From Reykjavik to London, companies shortened the workweek — and the results surprised almost everyone.

The Largest Workweek Trial in History

In 2022, sixty-one UK companies joined the biggest trial of a shorter workweek ever run. Around 2,900 staff worked one day less each week, with no cut to pay. The model, often called 100:80:100, asked workers to keep 100% of their output while working 80% of the time. Similar trials had already finished in Iceland, New Zealand, and parts of Belgium, but the British project was the most ambitious. Organisers hoped to discover whether a shorter week was simply a dream, or a realistic future for the way we work.

Productivity Held Up — and Sometimes Grew

The headline number was clear: productivity stayed the same or improved at most companies. Several businesses reported that employees handled the same workload in fewer hours, often because meetings were shortened and focused work increased. Across the UK group, revenue rose modestly during the trial compared with the same period the year before. Researchers say the results suggest that long hours do not always mean more value, and that smarter scheduling can match or beat a five-day week.

A Real Boost for Well-Being

Perhaps the most striking outcome was the change in how people felt. Surveys showed that stress levels fell, sleep improved, and workers had more time for family, exercise, and hobbies. The extra day off allowed staff to commute less, cook real meals, and pick up children from school without rushing. Mental and physical well-being scores rose sharply, and staff turnover dropped. For many employees, the shorter week was less about working less and more about living more.

Why Some Companies Went Back

Not every business chose to continue. Smaller firms and customer-facing teams, such as restaurants and call centres, often found it harder to adapt. With fewer people on duty, customer service suffered, and the cost of hiring extra cover rose. Some managers also struggled with the implementation of new shift patterns, especially when workloads changed with the seasons. By the end of the trial, around 56 of the 61 UK companies said they wanted to keep a shorter week, but several later reduced the change to Fridays only.

What's Next for the Five-Day Week?

The reduction of one working day may sound small, but it challenges a pattern that has shaped office life for nearly a century. Politicians in several countries are now discussing whether a four-day week could become a legal option, while others warn it is not sustainable in every sector. Many companies are finding middle paths: a nine-day fortnight, summer Fridays, or seasonal hours. Whether the five-day week survives or slowly fades, the trials have already changed the conversation about work, time, and what a fair week really looks like.