Four-day work week and wellbeing: what the pilots actually show

What the data actually shows

The four-day work week has moved past opinion pieces. There are serious pilots now, with real metrics and real companies. The pattern that emerges is more nuanced than most LinkedIn takes suggest.

The pilots that matter

United Kingdom, 2022. 61 companies, 2,900 employees, six months, organized by 4 Day Week Global. Self-reported burnout dropped 71%. Revenue held steady or grew slightly. 92% of participating companies decided to continue.

Iceland, 2019-2021. The largest study to date: 2,500 public sector workers. Wellbeing improved in roughly two-thirds of the roles analyzed, with no drop in productivity. Today 86% of Iceland's workforce has access to shorter hours.

Belgium, 2022. Legalized the option to compress the week into 4 days. Hours are not reduced, they are packed together. Wellbeing outcomes were significantly worse than in the UK or Iceland.

Spain, 2023-2024. The Ministry of Industry funded a pilot with 41 small and mid-sized companies. Mixed results: gains in satisfaction and retention, but operational headaches in several sectors. Desigual tested a four-day week at its headquarters before most others. Telefónica launched a voluntary pilot in 2022.

Where it works and where it struggles

Works well in tech and software development, professional services, knowledge and administrative work, teams with autonomy and measurable goals.

Struggles in hospitality, healthcare, retail, and manufacturing with continuous production lines.

The most common mistake

The biggest risk is not team resistance. It is packing 40 hours into 4 days instead of reducing to 32. When that happens, burnout gets worse.

What to measure if you try it

Team wellbeing and exhaustion (short monthly surveys), productivity measured by outcomes, retention and turnover, customer or user satisfaction. A serious pilot runs at least 3 months.

So, yes or no?

The evidence suggests that, done right, a four-day week improves wellbeing without hurting the business. Successful pilots share three things: real hour reduction, redesigned meetings and processes, and clear metrics from day one.

See how Harmony helps measure wellbeing and detect burnout →

Natalia Cuadrado is the founder of Harmony.