A peer-reviewed study published in Nature Human Behaviour in July 2025 tracked 2,896 employees across 141 companies in six countries during a six-month four-day workweek trial. The results showed reduced burnout, higher job satisfaction, and improved mental and physical health with no drop in output. As a result, more than 90% of participating companies chose to continue with the shortened schedule after the trial ended.
This data shows that a four-day work week does actually work. But what most of the headlines skip is how companies actually measured whether it was working.
That’s the part that matters if you’re considering running your own pilot.
However, without a measurement framework, a four-day work week might not be as productive. And that is what we will be discussing in this article—how to build the framework that turns a schedule experiment into an informed business decision.
Why 4-Day Work Week Productivity Needs a Measurement Plan
The most common model for reduced-hours experiments is the 100:80:100 principle:
- 100% of pay
- 80% of the time
- 100% of output
That last part is the hard one. “100% of output” requires you to actually know what 100% looks like before you change anything.
In the UK’s 2022 pilot with 61 companies and roughly 2,900 workers, participating organizations spent about eight weeks restructuring workflows before the trial even began. They cut unnecessary meetings, consolidated communication channels, and identified which tasks actually drove results versus which ones just filled time.
That preparation phase (establishing baselines and redesigning work) is what separated successful pilots from chaotic ones.
The 5 Metrics That Matter for Compressed Workweek Tracking
The best way to measure the success of a 4-day week is to track indicators that tell you whether your team is delivering the same (or better) results in less time.
1. Output Per Hour, Not Just Total Hours
Total hours worked will obviously drop in a four-day week. And that’s the point. You should instead look at the output relative to time invested.
Track deliverables completed, tasks closed, projects advanced, or whatever your team’s natural unit of work is. Then compare these numbers week-over-week and month-over-month against your pre-pilot baseline.
The UK pilot found that around half of participating employers reported productivity either stayed the same or improved and revenue across the trial group rose by an average of 1.4%.
2. Active Work Time vs. Passive Time
One of the patterns that emerges when teams shift to a four-day schedule is a natural reduction in low-value time. People become more intentional about how they spend their hours because each one carries more weight.
Time tracking makes this visible. When you can see how much of a workday goes to deep focus versus meetings, email, or administrative tasks, you can identify where compression is happening naturally and where bottlenecks persist.
A tool like WebWork breaks this down automatically, categorizing time by app, website, and project so you can see whether your team’s 32 hours are being spent on high-impact work or getting eaten by the same time sinks that plagued their 40-hour weeks.
3. Quality Indicators
Producing the same volume of work faster means nothing if quality drops.
The Nature study addressed this concern directly. Researchers had expected that compressing work into fewer days might increase stress and lead to rushed output. But instead, they found the opposite as employees reported that their ability to perform actually improved.
4. Attendance and Reliability
The UK pilot measured a 57% decrease in employee turnover and a 65% reduction in sick days during the trial period. These numbers suggest that reduced schedules can improve both retention and day-to-day reliability.
For your own pilot, track absence rates, late starts, and unplanned time off before and during the experiment. Attendance monitoring gives you a concrete data point that’s hard to argue with, either people are showing up more consistently or they’re not.
WebWork’s attendance monitoring tracks punctuality, shift compliance, and absence patterns automatically, which gives you a clean before-and-after comparison without asking managers to manually log who showed up when.
5. Employee Wellbeing and Engagement
This is the one metric where surveys are actually the right tool. The Nature study used structured questionnaires before and after the trial to measure burnout, stress, fatigue, sleep quality, and overall life satisfaction.
Their findings showed 71% of participants in the UK trial reported reduced burnout, and 39% reported lower stress levels. These gains held steady even at the 12-month mark, suggesting they weren’t just a novelty effect.
Our suggestion is that you run a simple wellbeing survey before your pilot starts and keep doing it at regular intervals during it. Keep the questions consistent so you can compare over time. Pair survey data with objective signals such as overtime patterns, irregular hours, skipped breaks, and sustained high-activity periods without rest to complement what employees report in surveys. For an effortless process, use WebWork’s burnout risk detection tool and you’ll have all those metrics automatically.
How to Set Up Your Measurement Baseline
Before launching a four-day week pilot, spend at least four to six weeks collecting baseline data on your current five-day schedule:
Time allocation
How many hours per week does each team or role spend on core work versus meetings, admin, and context-switching? Time tracking during the baseline period establishes the denominator for every productivity calculation you’ll run later.
Deliverable velocity
How many tasks, tickets, projects, or units of work does each team complete per week? This becomes your output benchmark.
Quality metrics
What are your current error rates, revision counts, or customer satisfaction scores? You need a stable baseline to detect any changes during the trial.
Attendance patterns
What’s your current rate of sick days, late starts, and unplanned absences? If these improve during the pilot, that’s a data point worth having.
If you want to see how time tracking fits into your baseline measurement before committing to a full pilot, you can try WebWork free for 14 days. It takes about five minutes to set up and starts collecting the kind of data you’ll need from day one.
Running the Pilot: Week-by-Week Tracking That Works
The strongest four-day week pilots share a common structure: a defined timeline, regular check-ins, and consistent measurement throughout. Based on how the major trials were organized, here’s a practical tracking framework.
Weeks 1–2: Restructure and Recalibrate
The first two weeks can be messy as teams are adjusting to the new schedule.
During this phase, track time allocation closely but don’t draw conclusions from it. The goal is to observe how work patterns shift.
Weeks 3–8: Measure and Compare
By week three, most teams have settled into a routine. This is when your data starts becoming useful and you can compare weekly output against your baseline. Look at time-per-task trends and monitor whether quality indicators are holding steady.
WebWork’s productivity insights break work time into categories: active versus inactive time, productive versus non-productive app usage, and focus time versus shallow time. These breakdowns are especially useful during a compressed workweek because they show whether your team is achieving genuine efficiency gains or just working at a more frantic pace.
Weeks 9–12: Evaluate and Decide
The final phase is about synthesizing your data into a decision. Compare your pilot metrics against your baseline across all five measurement categories. You are very likely to be surprised at the results.
The companies in the UK and global trials chose to continue with the four-day week after their pilots ended. Your pilot should give you the same clarity.
The Role of Time Tracking in Work Redesign Experiments
The four-day workweek is part of a broader shift toward measuring work by outcomes rather than hours. That shift requires better visibility into how time is actually spent. Not to monitor employees more closely, but to understand where time creates value and where it doesn’t.
WebWork fits naturally into this model. Its AI-powered work categorization automatically classifies time as productive, neutral, or non-productive based on the tools each role uses, without requiring anyone to manually label their activities. Activity descriptions let employees add context to their tracked time and can even be filled automatically by AI based on work activities. And scheduled reports give you a weekly view of trends so you don’t have to check dashboards daily.
For a four-day week pilot specifically, the combination of automatic time tracking, app and website categorization, productivity scoring, and burnout detection gives you the measurement layer that turns a schedule experiment into a data-driven decision.
Plans start at $3.99 per user per month, which makes it practical to instrument a pilot without a significant upfront investment.
Want a guided walkthrough of how WebWork’s tracking and reporting would work for your four-day week pilot? WebWork’s team offers live demos that you can book right now.
Moving from Experiment to an Actual 4-Day Work Week
The evidence from the largest trials conducted so far points in one direction: reduced work schedules can maintain or improve output while meaningfully improving employee wellbeing.
Whether you’re running a six-week test with a single team or a six-month company-wide pilot, the fundamentals are the same. Establish baselines before you start. Track output, time allocation, quality, attendance, and wellbeing consistently throughout. Use the data to iterate during the pilot, not just to evaluate it at the end. And choose tools that give you visibility without creating the kind of surveillance culture that undermines the trust a four-day week is supposed to build.
The question for most companies is no longer whether the four-day work week can work, but whether they can measure it well enough to prove it works for them.
