Does the Four-Day Week Work? What Trials Really Found
Trials show promising wellbeing and retention results, but success usually follows work redesign and the evidence is not a universal productivity guarantee.
- Published
- 25 July 2026
- Reviewed
- 25 July 2026
- Next review
- 25 January 2027
- Reading time
- 9 minutes
On this page
Answer First
The practical answer
Four-day-week trials generally report better wellbeing and strong retention, with many participating employers continuing the arrangement. The strongest recent multi-country study found improvements in burnout, job satisfaction and health after reduced-hours trials. However, many organisations volunteered, outcomes often rely on self-report, and a four-day week can mean reduced hours or merely compressed hours. The model works best as work redesign, not as five days of demand squeezed into four.
Who This Affects
Use this guide if any of these describe you
- Employees considering a shorter-hours employer
- Managers planning a pilot
- Leaders evaluating productivity and staffing risk
- Teams in customer-facing or continuous-coverage work
Evidence Strength
ModerateEditorial format
Evidence CheckPortfolio role
Evergreen decision pageKey takeaways
- A true reduced-hours model is different from four longer compressed days.
- The evidence for wellbeing is stronger than the evidence for universal productivity gains.
- Removing low-value work and protecting coverage are central to a credible pilot.
First define the four-day week
A 100:80:100 model aims for 100% pay, roughly 80% of previous hours and maintained output. Compressed hours keep total hours but fit them into four days. A staggered model gives different people different days off.
These models create different fatigue, cost and customer effects. Any claim about success should name the model actually tested.
What the trials found
The 2025 Nature Human Behaviour study analysed 2,896 employees across 141 organisations and compared results with 12 control organisations. It reported improved burnout, job satisfaction, mental health and physical health after reduced-hours trials.
The UK and Iceland reports also describe maintained services or revenue alongside shorter hours in many participating workplaces. They add useful implementation detail, but selection and before-and-after designs limit causal certainty.
Where confidence should stop
Volunteer organisations may be more committed and better prepared than average. Short trials can miss later workload creep, promotion effects and staffing costs. Self-reported productivity is not the same as audited output.
The evidence is thinner for emergency services, schools, retail, hospitality, manufacturing and other settings that need continuous physical coverage.
What a credible pilot looks like
Define hours, pay, eligibility, customer coverage and measures before launch. Remove low-value meetings and hand-offs rather than relying on faster individual effort. Track output, quality, absence, overtime, wellbeing and customer outcomes.
Set stop, adapt and continue rules. Review effects by role and caring status so the average does not conceal an unfair workload transfer.
Related profession guidance
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Sources
Read the evidence behind this guide
- Original research21 July 2025Nature Human Behaviour: Work time reduction via a 4-day workweek finds improvements in workers' well-being
Pre- and post-trial evidence from 2,896 employees in 141 organisations, with 12 control organisations.
- Primary reportFebruary 2023Autonomy and 4 Day Week Global: The results are in: The UK's four-day week pilot
Pilot report. Participating employers self-selected, which limits causal claims.
- Primary reportJuly 2021Autonomy and Alda: Going Public: Iceland's journey to a shorter working week
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