Working Late? You Could Be Wasting Your Time

Your twenties are for working hard. That doesn’t mean not having a great time or spending more time at the pub than you probably should, just that your social escapades need to be balanced with some darn hard work to make sure your career gets off to a cracking start.

But exactly how hard do you need to work?

A recent study by Stanford University economics professor John Pencavel suggests that it’s not really worth spending too much more than a standard working week at your desk. The reason to limit the hours you work, as Pencavel explains in his paper The Productivity of Working Hours, is that productivity declines after a certain point.

“Below an hours threshold, output is proportional to hours; above a threshold, output rises at a decreasing rate as hours increase.”

In layman’s terms, that means that after a certain number of hours each week, you’re less productive in every extra hour you work. That decline in productivity kicks in at 50 hours, or as Pencavel’s paper explains, “the marginal product of hours is a constant until the knot at 49 hours after which it declines.”

The chart below shows how sharply your work drops off after that point.

productivity of hours worked

Chart: The Productivity of Working Hours, John Pencavel

So there’s a pretty strong case for limiting yourself to five, ten hour days and remaining wide open for weekend shenanigans.

To get to this conclusion, Pencavel looked at data from the Health of Munition Workers Committee (HMWC) during the first world war. As manual labour workers, these munitions teams had very tangible output to measure their productivity from.

The findings were also set out in a simple chart of output against hours worked, below. As you can see, the stall in output at around 50 hours is obvious.  Even the poor buggers putting in over 70 hours a week were pretty well on par with the rest of the pack.

productivity of hours worked chart

Chart: The Productivity of Working Hours, John Pencavel

So next time you’ve got your axe to the grindstone, remember not to hold it there for too long. You might just be making it blunt.

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