A year after the world's biggest 4-day week trial wrapped, the vast majority of companies have kept it in place

• A year after the world's largest 4-day workweek trial ended, most companies are carrying on with it.
• 92% of the participant companies are still on the reduced schedule, researchers said Wednesday.

The vast majority of companies that took part in a massive UK trial of a four-day working week are still on the reduced schedule more than a year later, researchers said Wednesday.

Out of 61 companies that took part in the six-month trial in 2022, 54 have continued with the shortened week, with 31 of them — or 51% — saying this is a permanent decision.

The report comes as a follow-up to results published from the largest-ever trial of a four-day working week completed so far.

"It's hard to overstate how good it's been," one of the participants told Business Insider's Beatrice Nolan after the trial's end.

The CEO of one participating consultancy quoted in the study said: "When you realise that day has allowed you to be relaxed and rested, and ready to absolutely go for it on those other four days — you start to realize that to go back to working on a Friday would feel really wrong. Stupid actually."

What's more, the reduced working time didn't cause a loss in company revenue, the researchers said in a summary presented to UK lawmakers in 2023.

That report said that on average, the companies that shared data saw an average 1.4% revenue increase between the start of the trial and its end.

When looking at a comparable six-month period prior to the trial, that average change increased to 35%, the study said.

The companies involved included online retailers, animation studios, financial service providers, and even a small fish and chip shop.

Workers reported increased work-life balance, a reduction in stress and anxiety, and improved mental and physical health.

The trial involved about 2,900 workers, and took place from June to December 2022, with companies maintaining existing levels of pay.

How the reduced working time was put in place varied from company to company, the study said.

"A range of four-day weeks were therefore developed, from classic 'Friday off' models, to 'staggered,' 'decentralised,' 'annualised,' and 'conditional' structures," the researchers said.

Ahead of the trial, companies committed to a two-month preparation period that included workshops and mentoring, as well as support from companies that had already made the move, the study said.

The study was conducted by researchers at the UK's University of Cambridge, the University of Salford, and independent research organization Autonomy.

The study's results were broadly in line with other flagship experiments in recent years.

Last June, a New Zealand nonprofit released the results of a year-long, 4-day workweek trial that took place across multiple countries, which found that company revenues actually increased by 15%.