Four-day working week: trial results

Since 2015 Europe has seen several trials in which companies and public bodies cut working hours without cutting pay. Most of them, however, had no control group, and the companies signed up of their own accord. The results should therefore be read with care.

What did the UK trial show?

In the second half of 2022, 61 companies with around 2,900 staff tried a shorter week in the UK. Average working hours fell from 38 to 34 a week. After the trial ended, 56 companies carried on, and a year later at least 54 still did, or 89%. At least 31 companies had made the shorter week permanent after a year.

Companies reported fewer resignations and sick days, but the authors themselves note that these differences are not statistically significant. Companies did not measure productivity in a consistent way. According to the survey, 15% of employees would not go back to a five-day week for any amount of money.

Sources: Autonomy, pilot results, Autonomy, one year on

What did the German trial with a control group measure?

The German trial in 2024 was evaluated by the University of Münster. By October 2024, 41 of the 45 organisations had completed it or were about to. It was one of the few with a control group (employees within the participating organisations) and with physiological measurements: smartwatches and levels of the stress hormone in hair. Participants had considerably fewer minutes of stress a day than the control group and slept 38 minutes a week longer. The companies' financial results barely changed, and the fall in sickness absence was not significant. More than 70% of the organisations wanted to stay on the shorter schedule.

Source: University of Münster

How did the trials in Portugal, Iceland and Poland turn out?

Portugal launched a government pilot in 2023 without any state funding. According to the interim report, working hours fell from 39.3 to 34 a week and work-related exhaustion by 19%. Of the 108 companies that showed interest, 21 entered the coordinated test.
Iceland tested a week of 35 to 36 hours between 2015 and 2019, not a four-day week. Some 2,500 workers took part, and according to the report productivity and services stayed the same or improved in most workplaces.
Poland has, since 1 January 2026, been subsidising shorter working hours at selected employers, with up to 1 million zlotys each. The ministry picked 90 employers from 1,994 applications and will publish a summary report once the one-year pilot ends.

Sources: Portugal, interim report (in Portuguese), Alda and Autonomy, Poland, ministry (in Polish)

Why read the results with care?

The trials attract companies that want a shorter week and expect it to pay off. Reviewers of a study in Nature Human Behaviour, which pooled trials from six countries, pointed to a missing or small control group. In their reply the authors acknowledged that the results probably overstate the effect. Most of the trials were also co-organised by 4 Day Week Global, an organisation that campaigns for a shorter week.

Source: Nature Human Behaviour, peer review reports

What does Czech law allow?

The standard working week is 40 hours (Labour Code, Act No. 262/2006 Coll., Section 79(1)). It can be shortened without a cut in pay through a collective agreement or an internal regulation. Employers that pay public-sector salaries cannot do this, for example the state, regions, municipalities, state funds and some publicly funded organisations (Section 79(3), Section 109(3)). Working time is scheduled "as a rule" over a five-day week (Section 81(2)) and a shift can last up to 12 hours (Section 83(1)), so the law does not rule out a four-day week. Part-time hours are agreed in writing, with pay to match (Section 80).

Part-time work is less than half as common in Czechia as the EU average: in 2025, 7.8% of workers aged 20 to 64 were part-time, against 17.0% in the EU. Full-time workers put in almost the same hours in Czechia and the EU, 40.7 and 40.3 a week.

Sources: Labour Code (in Czech), Eurostat, part-time employment, Eurostat, usual weekly hours

Summary

In the UK, 89% of the companies in the trial were still on a shorter week a year later.
The German trial, one of the few with a control group, measured less stress and longer sleep, but financial results did not change significantly.
The trials were not randomised, so the results are closer to an upper limit. Czech law allows a shorter week without a pay cut through a collective agreement or an internal regulation.

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As of 1 November 2026. This article is general information, not legal advice.