Most leaders first hear “four-day week” and picture the same work, squeezed into fewer days, for the same pay. That picture causes most of the confusion.
At Day5Group, we help organisations transition to a four-day week using the model that sits behind nearly every serious trial to date: 100-80-100. Staff receive 100% of pay, work 80% of their previous time, and commit to 100% of their previous output. The commitment matters. This is not a gift of a day, and it is not a part-time arrangement with a new name. It is a redesign bargain: the organisation gives time, and teams give a better way of working.
What 100-80-100 actually means
100% pay comes first, because it changes behaviour. If pay falls in proportion to hours, staff who can least afford a cut opt out, hourly workers lose income, and you have simply offered part-time work. The researched model keeps pay whole so the conversation can be about output and waste, not about who can afford to participate.
80% time usually means around 32 hours instead of 40, most often worked as four days. It does not have to mean Friday for everyone, and in coverage businesses it rarely should. The principle is a genuine reduction, not four very long days that add up to the same total.
100% output does not mean 100% of every activity you do today. It means 100% of the results your customers, patients, students or clients actually value. The gap between those two definitions is where the work happens. Meetings that produce no decision, reports nobody reads, approvals that add no control, and handoffs that create waiting are all activity. They are not output.
What it is not
It is not compressed hours. Working 40 hours in four 10-hour days is a compressed week. That can suit some rosters, but it is a different intervention, with different effects on fatigue, childcare and overtime law. We will return to that distinction in a later article, because mixing the two models up leads to disappointed expectations.
It is not “Summer Fridays” with better branding. A seasonal perk leaves contracts, workloads and client promises untouched, then quietly returns in September. A 100-80-100 pilot changes how work is planned, measured and covered, and it ends in an explicit decision: continue, adjust, or stop.
It is not a productivity trick that works by making people move faster for eight hours. If the only plan is intensity, staff will feel it within weeks. The early evidence we do have points the other way: Perpetual Guardian in New Zealand (2018) maintained output during its monitored trial while stress fell and work-life balance scores rose sharply; Iceland’s public-sector trials (2015-2019, reported by Autonomy and Alda in 2021) maintained or improved service in most workplaces while hours fell from 40 toward 35-36.
Neither case proves every firm will succeed. They show the model is testable, not fanciful.
The three questions every team must answer
Before a pilot, each team needs plain answers to three questions.
First, what is our 100%? Name three to five outputs that matter: cases resolved to standard, projects delivered on time, clients served within an agreed response time. If a team cannot name its outputs, it is not ready to trade time for them.
Second, what will we stop? A day cannot be found; it has to be released. That means a stop-doing list agreed before the pilot starts: meetings to kill or shorten, reports to automate or end, approvals to remove. Without this, the fifth day’s work migrates into evenings.
Third, who covers what, when? Customers do not experience your rota; they experience response and resolution. Stagger days, use shared queues, and publish service promises you can keep.
A practical way to start
Do not announce a date on day one. Run a short readiness period:
- Map demand by day and hour for four weeks.
- Define output measures and take a baseline.
- Inventory meetings, reports and approvals, with hours attached.
- Draft the stop-doing list with the people who do the work.
- Check contracts, overtime status and leave in plain language with HR advice.
- Agree in advance what “good enough to continue” looks like.
Only then choose a pilot start, a duration long enough to include a busy period, and a decision date.
That sequence is slower than deleting Friday from the calendar. It is also why pilots designed this way tend to survive contact with reality.
If you are weighing whether 100-80-100 fits your organisation, start with the three questions above. Your answers will tell you more than any headline.
Sources
- Perpetual Guardian trial, New Zealand (2018), academic monitoring by Auckland universities — reported in ScienceAlert, 2018.
- Iceland public-sector shorter-hours trials 2015-2019 — Autonomy and Alda, reported July 2021.
Day5Group is a consultancy that assists in the transition to a 4 day work week. More about Day5Group · All blog articles