The 240 employees at New Zealand trust company Perpetual Guardian will be able to switch to a four-day work week from November after a trial run proved a hit, the company announced Tuesday.

"For us, this is about our company getting improved productivity from greater workplace efficiencies," founder and managing director Andrew Barnes said in a statement.

In March the company started the experiment allowing all 240 staff to retain full pay while working only four days a week.

While productivity increased, the staff's well-being and engagement also improved through the trial. "There's no downside for us in going ahead with this," Barnes said.

Employees who opt in to the four-day week will be eligible for a weekly "rest day" as long as they met their weekly productivity objectives, and would be paid at their usual salary.

A team of researchers led by Professor Jarrod Haar of the Auckland University accompanied the trial to observe the impact on the workforce.

He said supervisors found their teams were able to keep up their regular job performance and improve customer service, while employees reported increased job satisfaction and work-life balance, and less stress.

"To me, the data strongly supports the benefits for the psychological and physical well-being of workers - and the performance gains for employers: a true win-win proposition," Haar added.