The pilot, which will last for six months, involves 3,300 workers spanning 70 companies, ranging from providers of financial services to a fish-and-chip restaurant.
During the program, workers receive 100% of their pay for working only 80% of their usual week, in exchange for promising to maintain 100% of their productivity.
The program is being run by not-for-profit 4 Day Week Global, Autonomy, a think tank, and the 4 Day Week UK Campaign in partnership with researchers from Cambridge University, Oxford University and Boston College.
SEE ALSO: Some US companies explore 4-day work week
Sienna O'Rourke, brand manager at Pressure Drop Brewing, an independent brewery in London, told CNN Business that the company's biggest goal was to improve the mental health and well-being of its employees.
"The pandemic [has] made us think a great deal about work and how people organize their lives," she said. "We're doing this to improve the lives of our staff and be part of a progressive change in the world."
Given the company manufactures and ships products, workers have less flexibility about when and where they work, O'Rourke said. But any difficulties in navigating holiday and sick leave would be tackled as a team.
Until now, Iceland had conducted the biggest pilot of a shorter working week between 2015 and 2019, with 2,500 public sector workers involved in two large trials. Those trials found no corresponding drop in productivity among participants, and a dramatic increase in employee well-being.
MORE: Iceland's shorter working week trials an 'overwhelming success'
Calls to shorten the working week have gathered steam in recent years in several countries. As millions of employees switched to remote work during the pandemic -- cutting onerous commuting time and costs -- calls for greater flexibility have only grown louder.
Government-backed trials are set to take place in Spain and Scotland later this year, the 4 Day Week Campaign said in a press release.
Joe O'Connor, CEO of 4 Day Week Global, said that the workers have shown they can work "shorter and smarter."
"As we emerge from the pandemic, more and more companies are recognizing that the new frontier for competition is quality of life, and that reduced-hour, output-focused working is the vehicle to give them a competitive edge," he said in the statement.
Researchers will measure the impact the new working pattern will have on productivity levels, gender equality, the environment as well as worker well-being.
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