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Simulate weekly hour impact from compressed shifts.
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Compressed workweek models are gaining rapid adoption as organisations compete for talent and workers seek better work-life balance. But shifting from a standard 5×8 schedule to a 4×10 or 9/80 arrangement changes more than just the calendar — it reshapes coverage windows, fatigue risk profiles, overtime thresholds, and operational continuity. The simulator above helps you model all of these effects before committing to a compressed schedule.
Four 10-hour shifts per week. Employees get a three-day weekend. Total weekly hours: 40. Coverage is concentrated into 4 days, with no coverage on the fifth day unless teams are staggered.
Eight 9-hour days and one 8-hour day over two weeks, producing one day off per fortnight. Total hours: 80 over 9 working days. Maintains near-daily coverage with one predictable day off every two weeks.
Three 12-hour shifts per week. Common in healthcare and manufacturing. Total weekly hours: 36. Provides four days off but creates significant fatigue risk in the third consecutive 12-hour shift.
Teams A and B each work 4×10, with their off-days staggered (e.g., Team A off Monday, Team B off Friday). Combined coverage spans all 5 days while individuals still get a three-day weekend.
When modelling shift compression, the key question is whether total coverage hours across the week change. For a 4×10 arrangement with a single team:
Weekly Coverage Hours = Shifts per Week × Hours per Shift × Qualified Staff
5×8: 5 × 8 × 10 = 400 staff-hours/week | 4×10: 4 × 10 × 10 = 400 staff-hours/week
Total hours are identical — but the distribution changes. The 4×10 model produces zero coverage on the fifth day, which may be operationally unacceptable without staggering:
Daily Coverage Gap = Required Daily Staff − Staff Scheduled on That Day
Example: 10 required on Friday − 0 scheduled (all on day off) = 10-person gap requiring mitigation
Research on compressed workweeks consistently shows short-term productivity gains that may erode over time as fatigue accumulates in longer shifts:
| Shift Length | Typical Productivity Profile | Fatigue Risk | Incident Risk |
|---|---|---|---|
| 8 hours | Optimal | Low | Baseline |
| 10 hours | Moderate drop in final 2 hrs | Moderate | +8–12% vs 8-hour baseline |
| 12 hours | Significant drop in final 3 hrs | High | +27–30% vs 8-hour baseline |
Use the simulator above to compare coverage, hours, and overtime exposure between your current and proposed shift patterns.
In the US under FLSA, overtime is calculated on a weekly basis (over 40 hours), so a 4×10 schedule does not automatically trigger overtime. However, some states (California, for example) calculate overtime on a daily basis over 8 hours — meaning each hour beyond 8 in a 10-hour shift would qualify as overtime regardless of weekly total. Always verify your jurisdiction's overtime rules before implementing compressed shifts.
Leave entitlements become more complex under compressed schedules. An employee on a 4×10 arrangement uses more leave hours per day off than one on a 5×8. Ensure your HR system calculates leave in hours rather than days to avoid accidentally over- or under-accruing entitlement for compressed-schedule employees.
The 9/80 schedule spreads 80 hours across 9 working days in a two-week period, giving employees every other Friday off. Unlike 4×10, coverage continues on most Fridays — only one Friday off per fortnight — making it easier to maintain five-day service levels while still offering a three-day weekend once per pay period.
Yes, though proportional adjustments apply. A part-time employee working 30 hours per week could compress into a 3×10 schedule. The same coverage gap analysis applies — model the off-days across the team to ensure minimum coverage levels are met on every operational day.
Disclaimer: This calculator is for informational purposes only and does not constitute legal or financial advice. We do not guarantee the accuracy or completeness of the results. Please consult a qualified professional for advice specific to your situation.