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45 German companies tested the 4-day week for six months. The headlines afterwards: “Success!”, “Future of Work!”, “Breakthrough!”. The reality: 70 percent continue, 20 percent return to the 5-day week, and 10 percent are still undecided. That’s not a failure. But it’s not a no-brainer either. The honest assessment lies between the extremes – and that’s exactly where it becomes relevant for decision-makers.
Key Takeaways
- 70/20/10 distribution: 70 percent of pilot companies continue, 20 percent discontinue, and 10 percent are undecided (University of Münster/intraprenör, 2025).
- Revenue stable, not increased: Financial metrics remained at the previous year’s level – despite 20 percent less working hours. Implicit productivity increase, but no growth spurt.
- Significantly higher life satisfaction: Measurable improvements in sleep, exercise, and mental health. Absenteeism decreased in several companies.
- UK comparison: In the UK pilot (61 companies), 92 percent continued the 4-day week permanently. 62 percent reported less burnout (4 Day Week Global).
- Self-reported productivity +13 percent: Participants rated their own productivity at 7.69 out of 10 (control group: 6.83). Hard output data is largely lacking.
What the German pilot project really showed
From February to August 2024, 45 companies from across Germany tested the shortened workweek. The University of Münster, led by Prof. Julia Backmann, provided scientific support. The range spanned from a 12-person startup to a medium-sized production company. Most participants reduced their hours to 32-36 hours with full pay.
What is the 4-day week? The 4-day week refers to a working time model where the weekly working hours are distributed over four days – either with the same number of hours (compressed) or with reduced hours (typically 32 instead of 40) with full salary compensation. Most pilot projects test the reduced variant: fewer hours, same pay, same or higher productivity as a goal.
The results are nuanced. Revenue and profit remained at the previous year’s level. That sounds unspectacular, but it’s the crucial number: the same economic output with 20 percent less working hours implies a productivity increase of around 25 percent. Whether this is sustainable or a pilot effect (higher motivation, selection of engaged companies) can only be shown by long-term observation.
The Numbers Behind the Headlines
Sources: Uni Münster/intraprenör (2025), 4 Day Week Global UK Pilot (2023)
The self-reported productivity was significantly higher among participants than in the control group (7.69 vs. 6.83 on a 10-point scale). The Bertelsmann Foundation’s conclusion is sobering: the 4-day week is an opportunity for more flexible working time models, but it’s not a panacea and not a replacement for good leadership.
The 2-year follow-up (published February 2026) shows: 70 percent of participants continue to work in some reduced form. 22 percent have adapted their model – instead of sticking to the pure 4-day week, they’ve developed hybrid variants: 4.5 days, flexible Fridays, or seasonal models. This paints a more realistic picture than “4 days for everyone forever.”
Why 20 Percent Drop Out – and What That Says About Implementation
The 20 percent who dropped out are the more instructive part of the study. Their reasons can be condensed into three patterns:
Customer Contact Issues: Companies with a high proportion of external communication – agencies, consultancies, service providers – struggled to maintain availability. Customers expect five-day availability. An internal Friday off doesn’t work if the customer calls on Fridays.
Compression Stress: Squeezing 40 hours of work into 32 hours isn’t a reduction in working hours – it’s a compression of working hours. Some teams reported higher stress levels on the four working days because buffers and informal communication were lost. Life satisfaction increased on the free day, but pressure on working days also rose.
Inequality Within Teams: In companies with production-related and knowledge-based roles, a two-class society emerged. Office employees got the free Friday. Production, warehouse, and customer service had to remain staffed for five days. This inequality generated frustration that consumed the cultural benefits of the 4-day week.
The international comparison: UK as a benchmark
The British pilot project (61 companies, 2,900 employees, 2022-2023) provides the most robust data to date. The results are significantly more positive than the German ones: 92 percent of companies permanently adopted the 4-day week after the pilot. 62 percent of employees reported less burnout. 41 percent reported improved mental well-being.
Why the difference from Germany? Two factors: Firstly, the UK study was more focused on knowledge workers – industries where reducing working hours is easier. Secondly, the British pilot group was self-selected from companies that already had a high willingness to change. The German study had a broader mix of industries and thus more realistic results.
Iceland provides the longest dataset: Between 2015 and 2019, 2,500 employees (over 1 percent of the working population) tested the reduced week. The result: productivity remained stable or increased, well-being measurably improved. Today, 86 percent of Icelandic employees either work reduced hours or have the right to do so. Iceland is proof of concept at the national level – and at the same time proof that the transition doesn’t have to be disruptive but can be gradual.
What the data really say – and what they don’t
The honest assessment: The 4-day week works for knowledge workers in organizations willing to overhaul their processes. It doesn’t work as a simple “one day less” for everyone. It requires active process optimization, meeting reduction, and clear prioritization. Without this preparation, it’s just work intensification – and that makes people sick instead of productive.
What’s missing: Long-term data beyond two years. Hard output metrics instead of self-assessment. And an honest answer to the fairness question in mixed organizations. The 4-day week isn’t a gift to employees. It’s an organizational development project that only works if treated as such.
The counterposition: Critics argue that pilot projects take place under ideal conditions – highly motivated teams, media attention, temporary Hawthorne effect. The real test comes when the 4-day week becomes normal and initial enthusiasm wears off. The 2-year follow-up data show initial adjustments: 22 percent have already modified their model.
Three questions before making a decision
1. What proportion of value creation is location-independent? The higher the proportion of knowledge-based work, the better the 4-day week works. In organizations with more than 70 percent knowledge work, pilot data consistently show positive results. Below 50 percent, it becomes difficult without creating fairness problems.
2. Are meetings ready to be reduced? The most successful pilot participants reformed their meeting culture before reducing working hours: meetings from 60 to 30 minutes, asynchronous voting instead of meetings, “No-Meeting-Days”. Without this step, work just becomes more intense.
3. What’s Plan B? 20 percent of German pilot participants have returned to the old system. That’s not a failure – that’s an expected outcome. Anyone testing the 4-day week needs a defined evaluation period, clear metrics, and an exit plan that doesn’t trigger a debate about loss of face.
Conclusion
The 4-day week is neither revolution nor fad. It’s a working time model that works under certain conditions – and not under others. The 70/20/10 distribution of the German pilot is the most realistic result there is: a gain for the majority, not feasible for a fifth, and still unclear for the rest. For those considering it: six months of piloting with clear KPIs, honest evaluation, and a defined Plan B. Those who can’t set this up aren’t ready for the 4-day week – regardless of whether the idea works.
Frequently Asked Questions
Does productivity really increase with a 4-day week?
The data is nuanced. In the German pilot, sales and profits remained stable despite a 20 percent reduction in working hours – implying a productivity increase of around 25 percent. Self-reported productivity was 7.69 vs. 6.83 in the control group. Hard output data (unit numbers, code lines, contract closures) is lacking in most studies. The honest answer: productivity per hour demonstrably increases. Whether absolute output remains the same depends on the company.
Does the 4-day week work in production?
Significantly more challenging than in knowledge work. Production lines require physical presence and cannot be compensated by more efficient meetings. Some models work with shift systems (alternating Monday-Thursday and Tuesday-Friday), others with a 36-hour week instead of 32. The fairness question between office and production is the biggest obstacle in mixed organizations.
What does it cost to switch to a 4-day week?
Direct costs are manageable: process consulting, workshop moderation, pilot guidance. Indirect costs are higher: reorganization of processes, adjustment of IT systems, training of managers. Most pilot participants report a 3 to 6-month lead time. Revenue side: fewer absences, higher employer attractiveness, and potentially lower recruiting costs.
Is there a legal right to a 4-day week?
Not in Germany. The Part-Time and Fixed-Term Employment Act (TzBfG) gives employees the right to reduce working hours, but not to a specific distribution of days. The 4-day week at full pay is a voluntary employer decision. In Iceland, the majority of the working population already works reduced hours or has the right to do so. There is currently no EU legislation mandating a 4-day week.
How do I convince management to run a pilot project?
With numbers, not ideology. The three strongest arguments: first, German pilot data shows stable financial metrics with 20 percent less working time. Second, 62 percent less burnout (UK pilot) means fewer absences and lower turnover. Third, a 6-month pilot with defined KPIs and exit plan is low-risk. Pilot costs: manageable. Costs of absences and turnover: quantifiable. On this basis, a rational decision can be made – free from ideology in both directions.
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