Would a four-day week cut your pay? The 100-80-100 idea, real trials and what they found
A four-day week usually means about 32 hours for the same pay. The models, the history, what the big trials found and the open questions.
A four-day week does not have to mean less pay. The version most advocates push for is a fixed schedule of four eight-hour days, about 32 hours, following the 100-80-100 model: 100% of the pay for 80% of the time, in exchange for a commitment to keep at least 100% of the productivity. Other versions exist, though, and some of them simply squeeze the same hours into fewer days. This guide walks through the history of the idea, the main ways it is organised, what the best-known trials reported, the doubts that remain, and how a salary counter that already pays every day of the week, Paid Anyway, can help you think about it.
Why the week has five working days at all
The five-day workweek is a cultural norm rather than a law of nature. It came out of early 1900s union campaigns to cut the six-day week, which is how the weekend was invented. In the early 20th century, as the average working week in developed nations fell from around 60 hours to 40, many people assumed it would keep shrinking.
Famous predictions followed. In 1930 the economist John Maynard Keynes estimated that technological change and productivity gains would make a 15-hour working week possible within a couple of generations. In 1933 the United States nearly passed a 30-hour workweek bill, which collapsed under opposition from big business and a pivot toward full employment during the Great Depression. And in 1956 Vice President Richard Nixon promised Americans they would only have to work four days "in the not-too-distant future".
The idea came back strongly after the COVID-19 pandemic raised concerns about burnout and flexibility at work. During the 2023 United Auto Workers strike, organisers also pushed for a 32-hour week.
Shorter week or compressed week?
The single most important question to ask about any four-day week is which kind it is, because the answer decides what happens to your hours and your pay.
In the reduced-hours version, the week gets shorter: four eight-hour days for a total of 32 hours, under the 100-80-100 deal. Pay stays the same while hours fall, so your pay per hour worked effectively rises.
In the compressed version, the hours stay the same and are packed into fewer days. In the so-called "4/10" week, the common 40 weekly hours are spread over four ten-hour days. You get a long weekend, but each working day is longer. The 9/80 schedule sits between the two, alternating a four-day week and a five-day week every two weeks.
The day off itself can also differ. In some workplaces Friday becomes the permanent day off; some split the team so half take Monday and half take Friday; some add a mid-week break such as Wednesday; and some change the day from week to week depending on workload.
What the best-known trials found
The evidence comes mostly from trials, many of them in white-collar workplaces. In 2022 the advocacy group 4 Day Week Global ran six-month trials with companies in several countries, including a UK programme with 61 companies and around 2,900 employees that was described as the world's largest four-day week trial to date. The findings suggested that more than 90% of the UK companies would continue, with 18 firms making it permanent, and revenue at participating companies rose on average by more than a third compared with the same period in 2021.
Iceland is often cited, but with an important footnote. Two trials there between 2015 and 2019 cut hours to 35 a week without pay reduction for 2,500 workers and reported dramatically increased well-being, with productivity staying the same or improving in most workplaces. Yet the trials were about reduced hours, from 40 to 35 or 36, not necessarily a four-day week, and most workplaces removed up to three hours rather than a full day.
Single companies have reported striking results too. New Zealand trust company Perpetual Guardian ran a six-week trial in 2018 in which its 240-plus staff each nominated a day off while receiving full pay, and the company then made the scheme permanent. Microsoft Japan tried a four-day week in summer 2019, cut most meetings from an hour to half an hour, and reported a 23% fall in electricity costs and a 40% rise in sales per employee compared with the same period a year earlier.
Across more than 200 companies with 8,000 employees, sociology professor Juliet Schor found better retention, fewer sick and personal days, and better outcomes on all 20 well-being measures studied. She also noted that the 100-80-100 arrangement is not achievable for every company and depends on productivity improvements.
The doubts worth taking seriously
Not every story is a success. Utah moved its state government employees to ten-hour days from Monday to Thursday in 2008, hoping to save on running costs, but ended the practice in 2011. Even at Perpetual Guardian, some staff reported feeling more pressure to finish work in less time, especially around deadlines.
There is also the question of who benefits. Experts question whether the same arrangement works in blue-collar jobs, where there may be little wasted time, or where workers would have to work faster to keep output the same, potentially raising stress and lowering safety. The Marketplace radio programme has described the four-day week as a white-collar phenomenon. So when you read a glowing headline, it helps to ask what kind of work was involved, whether hours actually fell, and how long the trial ran.
Questions to ask if your employer proposes one
If a four-day week reaches your own workplace, a few plain questions clarify most of the deal. Is it reduced hours or compressed hours? Does pay stay the same, and if hours fall, is your contract changed or is it a trial? Which day is off, and is it fixed or rotating? What happens to targets: are they kept, lowered or raised? And how will the trial be measured and reviewed at the end? None of these questions are hostile. They are the same questions the researchers ask.
A counter that already pays every day of the week
Paid Anyway offers a playful way to picture all this. The app divides your annual salary by the days in the year, spreads each day's share evenly over all 24 hours, and keeps accruing regardless of working hours, weekends or holidays, with the number rising every 10 seconds. In other words, in the app's view your salary already arrives on every day of the week, including the ones you do not work.
That makes it a neat illustration of the 100-80-100 idea. If your annual salary stays the same, the counter's pace does not change at all when you move from five days to four; your new day off fills the month's jar exactly as fast as a working day did. What changes is the other side of the picture: the same money is now matched with fewer working hours. If you like, you can work out your own pay per working hour before and after, using the hours in your contract, and compare the two; it is the clearest way to see what a reduced-hours week really means.
If a compressed week is on the table instead, the counter also stays the same, because your pay does not change, but your working days get longer. The app cannot tell you whether that trade is worth it. It only keeps a steady reference point while you decide.
As always, the numbers are reference figures that leave out tax, social insurance, bonuses and allowances, so they may differ from what you are actually paid. Your salary and records are kept only on your device, with no account or login.
Key points
| Question | Short answer |
|---|---|
| Does a four-day week mean less pay? | Not in the 100-80-100 model; pay stays, hours fall |
| What is a compressed week? | The same weekly hours in fewer, longer days |
| What did trials report? | Better well-being and often steady output |
| What are the doubts? | Pressure, blue-collar fit and trials that ended |
| How does Paid Anyway see it? | Your salary already accrues on every day, worked or not |
The four-day week is an old dream with new data behind it. Whether it means more life for the same pay or simply longer days depends on the details, so read the fine print, ask the plain questions, and keep a steady number nearby to remind you that the year pays out the same way whichever day you have off.
This article is general information, not tax or financial advice. After-tax amounts in the app are estimates; check your payslip or a tax professional for exact figures.