A 9/80 schedule places 80 working hours into nine days over a two-week cycle. A 4/10 schedule places 40 working hours into four days each week. Both examples below total 80 hours across two weeks, but 4/10 provides two nonworking weekdays in that span while 9/80 provides one. Neither label alone specifies meal breaks, start times or legal overtime treatment.
Compare the same two-week window
| Feature | 9/80 | 4/10 |
|---|---|---|
| Week 1, Monday–Thursday | 9 hours each day | 10 hours each day |
| Week 1, Friday | 8 hours | Off |
| Week 2, Monday–Thursday | 9 hours each day | 10 hours each day |
| Week 2, Friday | Off | Off |
| Two-week working hours | 80 | 80 |
| Workdays | 9 | 8 |
| Nonworking weekdays | 1 | 2 |
These patterns assume weekends off. Other weekday placements are possible, so compare the actual dated roster rather than relying on a schedule name. The 9/80 daily pattern combines eight nine-hour days and one eight-hour day. The 4/10 pattern uses eight ten-hour days across the same fortnight.
Include breaks when comparing the day length
A nine-hour working day with a thirty-minute unpaid meal occupies nine and a half elapsed hours. Starting at 07:00 gives a 16:30 finish. A ten-hour working day with the same break ends at 17:30. The eight-hour Friday in this example ends at 15:30.
That extra hour on each 4/10 workday can change transportation, caring responsibilities and evening availability. Conversely, a weekly day off may be more useful than a fortnightly one. These are planning differences; the schedule arithmetic cannot decide which arrangement employees prefer.
Use the clock-out calculator to compare actual start, break and finish combinations. Do not count an unpaid meal as worked time solely to make a preferred departure time fit the pattern.
Keep overtime workweeks separate from calendar weeks
The 9/80 example contains 44 hours in the first Monday-to-Sunday calendar week and 36 in the second. Averaging them to 40 is not, by itself, a valid way to remove overtime. The general federal framework for covered nonexempt employees uses a fixed 168-hour workweek, with each workweek assessed separately.
Some 9/80 arrangements set a recurring workweek boundary during the working Friday. In this simplified example, a boundary after four working hours on Friday places four Friday hours plus the following Monday–Thursday's 36 hours into one 40-hour workweek. The other workweek contains 36 Monday–Thursday hours plus the first four hours of the next working Friday. Map the exact timestamps and breaks before relying on that arrangement.
This is an explanation of the hours allocation, not approval to alter payroll boundaries to avoid overtime. See the DOL workweek guidance. State daily-overtime rules, alternative-workweek requirements, agreements and exemptions can change the result. A 4/10 label is not an automatic exemption from those rules.
Compare Friday coverage rather than team totals
If every employee takes the same Friday off, the roster provides no coverage that Friday under either arrangement. Staggering days off may preserve service, but only if enough qualified people remain during each required interval.
Suppose four employees work the illustrated 9/80 pattern and two take each alternating Friday off. Two employees remain for eight working hours on either Friday: sixteen employee-hours before any additional coverage adjustment. With four employees on 4/10, moving two off-days to Monday leaves two people on Friday for ten hours each. That gives twenty employee-hours on Friday but reduces Monday staffing. The off-day does not disappear; it moves the capacity constraint.
Check breaks and skills as well as headcount. A daily total cannot establish that a reception desk, production station or support queue is covered continuously. The coverage calculator helps expose those intervals.
Choose using actual constraints
Compare the service window, minimum qualified staffing, employee availability, commute frequency and the exact payroll workweek. Test at least one full two-week cycle plus its boundary into the next cycle. Add a holiday or planned absence scenario separately instead of assuming the normal pattern still balances.
Document the chosen off-day groups and the date anchoring the cycle. Then share a dated roster so employees can see their assignments. For implementation details, use the existing 9/80 calendar guide or 4/10 versus 5/8 comparison. This page compares the two alternatives; those guides cover their individual construction.
Related calculators and guides
- Rotating Shift Calendar
- Calculate Weekly Coverage Hours Before Estimating Staff
- Calculate Shift Handover Overlap Hours
Explore more in Shift Schedules Calculators and Guides.