When you add up paid and unpaid work, it's women, not men, who put in the longer hours, largely because women tend to do more than their fair share of chores and childrearing. But it's in men's best interest, as well as women's, to close this "chore gap."

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The so-called Second-Shift isn’t just a figment of the imagination of working women irritated that they have to nag their husbands to do their fair share of the chores.

A new study by the Organization for Economic Cooperation and Development shows that across the developed world, women do far more of the unpaid domestic work that keeps households running, even when they’re also putting in many hours at work. Men, it’s true, tend to put in more hours at jobs than women do, but when you add together the total number of hours of work, both paid and unpaid, women worked more than men in all but a handful of the developed countries the OECD included in its analysis.

In the US, the difference in total time worked is significant but not enormous: On average, women put in 21 minutes a day more at work and at home than men do (which, coincidentally, is also the average for all OECD countries surveyed). The real difference is between paid and unpaid work — what you might call the “chore gap.” American men put in about 5 hours a day on the job; women put in four. But women make up the difference and then some at home, putting in a little over 4 hours on housework and childcare, compared to only 2.7 hours for men. The work of raising children still falls overwhelmingly to mothers, not fathers.

(MORE: More Women Are In the Workforce — So Why Are They Still Doing So Many Chores?)

The problem here goes well beyond resentment over who’s been doing their fair share of the dishes. The gender gap in total hours worked, and even more so the vast differences between men and women in paid and unpaid work, help to perpetuate some persistent inequalities. Obviously, women who work fewer hours earn less; they also tend to earn less per hour and get fewer benefits. And it’s hard to put in the hours necessary to compete in high pressure jobs when you’re pulling double duty at home.

While (unsurprisingly) women spend more time doing domestic work than men in all OECD countries, it is somewhat surprising to see that the gender gap in total hours worked varies tremendously from country to country. In several countries, including Norway, the Netherlands, and New Zealand, men actually put in more hours overall, while in Portugal and India women put in a lot more time than men — roughly an hour and a half a day.

So why does the “chore gap” persist? Conservatives like to say it’s the result of choice: Women prefer to spend fewer hours at work and more at home with the children. And there’s evidence that seems to back this claim up: A Pew Research study from 2007 found that 60% of working mothers with young children preferred part-time work; among working fathers, only 12% wanted to work part-time.

(MORE: Why Men Are Attracted to High-Earning Women)

But such “choices” aren’t made in a vacuum; they’re made in a culture that still largely sees chores and childrearing as “women’s work.” There’s considerable pressure put on men and women to hew to traditional roles. Indeed, one study of middle-class workers by researchers at the University of Toronto and Long Island University (you can find a pdf of it here) found that “fathers who violate … gender stereotypes by actively caregiving for their families” faced harassment and mistreatment at work. Women who either had no kids, or who left the childrearing to their husbands, likewise faced harassment for deviating from the traditional women’s role.

On the flip side, there are rewards for men who challenge the stereotypes and do their fair share of the chores: A number of studies have found that this makes for happier wives, and more sex. And one recent study on gender inequality startled the researchers that conducted it when it revealed that housework makes men happy, too. According to a University of Cambridge press release on the study, researchers “expected to find that men’s work-family conflict rose, and their well-being fell, when they did more housework. In practice, they found the opposite, with conflict falling, and well-being going up.”

So it’s in men’s best interests, as well as women’s, to try to close the chore gap.

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