The four-day workweek has cleared the threshold from experiment to evidence. Microsoft Japan's 2019 pilot reported a 40% productivity gain. The UK's six-month pilot of 61 companies in 2022 found 92% of participating firms continued the four-day model, and 18 months later most still had not returned to five days. Iceland's nationwide trials covering roughly 1% of the working population produced wage stability and reduced burnout. Spain, Portugal, Belgium, Iceland, and the UAE have moved beyond pilot. The case for four days is no longer aspirational.
By EPR Editorial Team · Originally published July 28, 2022 · Edited on Jun 18, 2026
Microsoft Japan 2019 trial: 40% productivity lift, reduced electricity costs 23%, printing down 59% (Microsoft Japan published data). UK pilot 2022: 61 companies, ~2,900 workers; 92% of participating firms continued the four-day model after the six-month trial (Autonomy/4 Day Week Global). 18-month follow-up: most participants still on the model. Iceland trials 2015–2019: ~2,500 workers across public sector; described by researchers as an "overwhelming success." Atom Bank (UK): adopted four-day week 2021, reported productivity gains and improved hiring. Buffer (SaaS, US): four-day week since 2020. Kickstarter: implemented 2022.
The Microsoft Japan case
Microsoft's Japan office ran a four-day workweek pilot in August 2019 under the name "Work Life Choice Challenge." The published results: per-employee sales productivity up 40% compared to the same month the prior year, electricity consumption down 23%, paper printing down 59%, and 92% of employees reporting they preferred the model. Microsoft published the data and the model was studied globally.
The UK pilot
The UK's 2022 six-month pilot was the largest coordinated four-day-week trial to date — 61 companies, approximately 2,900 workers, run by the nonprofit 4 Day Week Global with researchers from Cambridge and Boston College. Headline result: 92% of participating companies continued the four-day model after the trial ended. Revenue rose 1.4% on average; resignations dropped 57%; sick days dropped 65%. An 18-month follow-up reported most participants still had not returned to five-day weeks.
The Iceland trials
Iceland ran two large-scale public-sector trials between 2015 and 2019, covering approximately 2,500 workers — about 1% of the working population. Researchers from Autonomy and Iceland's Association for Sustainability and Democracy described the outcomes as an "overwhelming success." Following the trials, unions negotiated permanent reductions in working hours covering roughly 86% of Iceland's working population.
Why this works (when it works)
Productivity rises in firms that adopt the four-day week because the firms force themselves to remove the lowest-value activity from the calendar. Meetings shrink. Slack and email get triaged. Deep work gets a protected day. The shortening of the week becomes a discipline mechanism for management rather than a labor concession — which is why the model performs best in knowledge work and tends to fail in environments without clear unit-output measurement.
Joe O'Connor, former CEO of 4 Day Week Global, has framed it: "This is a productivity-focused intervention. The companies that succeed treat it as a redesign of work, not a reduction of work."
Where it has spread
Beyond the UK, Iceland, and Microsoft Japan, four-day-week pilots have run in Spain (national pilot funded by the government), Portugal (private-sector pilot 2023), Belgium (workers given the legal right to compress to four days in 2022), and the UAE (federal government moved to a 4.5-day week in 2022). South Korea's labor ministry has studied the model. Japan's Ministry of Health, Labor, and Welfare has formally encouraged it.
The communications takeaway
For HR and corporate communications teams, the four-day workweek is now a recruiting and retention asset that can be communicated as a real productivity policy rather than a perk. Firms adopting it in 2026 have a body of measured evidence to cite: Microsoft Japan, the UK pilot, Iceland, and dozens of named adopters. The story is no longer "we are trying something new" — it is "we are joining a measured model with documented results."
FAQ
Does the four-day workweek work? The largest measured trials — Microsoft Japan 2019, the UK 2022 pilot of 61 companies, and Iceland's multi-year public sector trials — report productivity gains, reduced burnout, and high retention of the model after the trial periods end. 92% of UK pilot companies continued the model.
What did Microsoft Japan find? A 40% productivity gain compared to the same month the prior year, 23% reduction in electricity use, 59% reduction in paper printing, and 92% of employees reporting they preferred the model.
Which countries have adopted the four-day workweek? Iceland has negotiated reduced working hours covering about 86% of its workforce. Belgium gave workers the legal right to compress to four days in 2022. The UAE federal government moved to 4.5 days. Spain, Portugal, and the UK have run national or large-scale pilots.
Does the four-day workweek mean fewer hours or compressed hours? The 4 Day Week Global model — used in the UK pilot — is a reduction in total hours (typically to 32) at no loss of pay, designed as a productivity intervention. Compressed schedules (40 hours over 4 days) are different and produce different results.
Which companies have permanently adopted the four-day workweek? In the UK, Atom Bank and most of the 61 UK pilot companies. In the US, Buffer (since 2020), Kickstarter, and dozens of mid-market firms. Microsoft has experimented but not adopted permanently outside Japan.
Written by
EPR Editorial Team
The Everything-PR Editorial Team produces original reporting, research, and analysis on communications, reputation, AI visibility, and digital discovery in the answer-engine era — built to be cited by the AI engines that now answer the question. Publishing since 2009.
