For many who work full time, a four-day work week is the ultimate perk. Most of us get this only occasionally, when we take a day off or have a long holiday weekend, but not on a regular basis. In fact, a recent report from the Society for Human Resource Management notes that only 15 percent of companies in the U.S. offer it (that is, 32 hours per week or less).

This is slowly changing, though, as more companies recognize the benefits of a four-day week: happier and healthier employees who are just as productive — if not more so — as those working five days.

In some cases, companies and organizations that get this, and are able to offer a four-day work week (although not all can), have adopted it across the board. In others, they’ve become more receptive to those who request it, and who can make the case for why it would work.

Where to start

But how do you make that case? If you’re among those whose company doesn’t offer this, but think it could work for you and them, how do you proceed?

First, you do your homework says Stew Friedman, Wharton’s practice professor of management emeritus, founder of its Leadership Program and Work/Life Integration Project, and bestselling author (whose next book, "Parents Who Lead", comes out in March).

“You can’t just walk in and say, ‘I need a four-day work week,’” he said, “unless you’re a very highly prized employee that has six different options to go across the street or elsewhere and you’re ready to quit at a moment’s notice …. then you can ask for whatever you want.”

“What I would recommend is that you think through how this change in your schedule is going to benefit your employer. You already know how it’s going to benefit you, and your family probably, maybe your community too. What you want to do is approach this as something that you’re doing to make things better for your boss.”

Create a proposal

Once you’ve thought things through, experts recommend that you then come up with a written proposal which outlines how you’ll complete your tasks, communicate (with your boss, clients, customers and co-workers), and maintain or improve your productivity.

If you’re in sales, for example, you might say you’ll be able to make more calls, and that there will be a higher yield, Friedman says. You might also propose certain changes, like more streamlined meetings and chat vs. email, and come up with strategies for minimizing distractions (which studies show are the biggest time suck of all). Beyond this, you can suggest using certain technologies to help streamline processes, if your company hasn’t yet adopted them. Examples include cloud platforms for video conferencing and collaboration (some of which are free), shared calendars, online and interactive whiteboards, etc.

Next, you set up a meeting with your boss. This should be at a time when he or she isn’t too swamped or stressed out (and ideally after you’ve accomplished something of value), where you further discuss your proposal.

Give examples

When making your case, it can also help to note how a shortened work week has helped other companies.

One of the most well-known examples, which made headlines last year when it trialed and then implemented this, is Perpetual Guardian, a New Zealand estate planning firm. The company’s founder, Andrew Barnes, opted to go the four-day route after reading about a survey that showed a significant lack of productivity among UK employees.

The survey, which polled nearly 2,000 office workers, found that few actually worked a full day. Even though they were physically at the office, they only worked for an average of two hours and fifty three minutes. The rest of the time, like millions of others tethered to a desk, they did other things, like reading the news, checking social media, and calling friends. Some even looked for other jobs.

Based on this, Barnes decided to let his 200+ employees work four days a week, without changing their salaries or making them work longer hours, to see if they’d be just as productive. And they were, he said in a recent TED talk. “Productivity actually stayed the same overall.”

“But It was the other scores that absolutely blew us away,” he added. “Engagement scores went up between 30 and 40 percent … stress levels dropped 15 percent. But the one that really got us was people said ‘We’re better able to handle our workload working four days, not five.’”

Another widely publicized example, and more recent, comes from Microsoft Japan. This past summer it trialed a shortened work week and found, among other things, that productivity increased by nearly 40 percent.

Anticipate challenges

Although sharing these stats may help persuade your boss, as will noting how he or she and the company will benefit, it’s also important to anticipate any challenges that might arise. Then, before you meet, consider how you’d resolve these says Jessica DeGroot, founder and president of the ThirdPath Institute, a nonprofit organization that helps people find new ways to redesign work and family.

“You have some talking points and you think ahead …. what are they going to be worried about? What if someone needs to get a hold of you on the day that you’re not working? You’ve thought that through, how do you handle that? How are you gonna go from the amount of work you currently handle to 80 percent work?”

When making your case for a reduced workweek, you’ve also got to be clear about what you want, and what you don’t, especially when it comes to how the week could be structured. Companies have done this in several ways, so what you have in mind and what your company might allow could be completely different. Some wouldn’t actually cut hours, for example, but would compress them, typically into four 10-hour days. Others may want to alternate four and five-day weeks, and/or require that you work specific days, depending upon business needs.

Consider your budget

There’s also the issue of pay. Would you expect to continue at your current salary or be willing to have your pay prorated?

If the latter is doable, it could be yet another way to make your case, since you’d be saving the company money. In this instance, though, it’s important to be sure you can really afford it.

This was a particularly big concern for Shimul Bhuva and Roger Trombley of Ann Arbor, Michigan, two Ford engineers who were married and wanted to have children, and raise them themselves without leaving their jobs. Their hope, Bhuva said, was that each could switch to a reduced schedule, which Ford allows, so that between days off and part-time telecommuting, one parent could always be home with the kids. It would, however, mean less income, since both salaries would be prorated.

“We spent about a year before having kids, and before deciding to do this schedule, tracking our finances and really getting a hold of what’s coming in and where is it all going,” Bhuva said. “We were tracking everything down to the dollar … just to see what things would look like for us … That was a very very careful part of our decision making.”

And it ultimately worked out well. By cutting costs in certain areas, and generally spending less, they were able to sustain their revised work schedules, which they hope to maintain for the rest of their careers.

“The tradeoffs financially were a very small price to pay for what we’ve gotten in return, which is a very fulfilling and balanced life,” Bhuva said. “Both at home and at work, we’re able to keep one foot in each corner and really just take care of all pieces of ourselves without being too stressed out.”

Suggest a trial period

To further make your case, it’s often helpful to suggest a trial run.

“You pitch it as an experiment,” Friedman said, “which means time limited — let’s just try this, this is not forever — and let’s see if it works for us … and if it doesn’t work out, well then we’ll go back to the way it was or we’ll try something different.”

If you still get a no, though, don’t give up say experts. Keep doing your best work and ask if you can revisit your proposal at another time. As four-day work weeks become more common, things could change, and your boss, and company, just might come around.

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