How Many Hours Should You Work Per Week?

The science on diminishing returns at work.

Ever since the pandemic forced us to re-evaluate how we work, concepts such as six-hour workdays and four-day workweeks have become widely talked about.

Many arguments have been made to suggest that we can work shorter hours without compromising productivity, creating space for more ‘me time’ and a boost to emotional wellbeing.

But what does the science say?

Aside from poorly run company experiments that don’t control for myriad contributing variables, a growing body of studies exists on the question of optimal working hours.

Stanford humanities professor, John Pencavel, published a discussion paper on the productivity of working hours in 2014. In it he found that below a certain threshold, the relationship between hours and output for laborers producing munition shells was linear.

Above that threshold, output rises at a decreasing rate. That threshold? 49 hours.

In 1914, Ford Motor Company cut working hours from nine to eight hours a day, and somewhat surprisingly, doubled wages. Within two years, margins had doubled.

But both of these examples focus on algorithmic, step-by-step manufacturing work.