A 9/80 calendar spreads 80 scheduled work hours across nine workdays in a two-week cycle. One arrangement uses eight nine-hour days, one eight-hour day and one weekday off. The cycle repeats every 14 days, so a useful calendar needs both an anchor date and the location of that day off.
Build the two-week pattern
In this example, Monday through Thursday are nine-hour workdays in both weeks. Friday in week one is an eight-hour day; Friday in week two is off. Week one totals 44 scheduled hours and week two totals 36. Together they total 80, averaging 40 per seven calendar days over the full cycle.
| Day | Week one | Week two |
|---|---|---|
| Monday | 9 | 9 |
| Tuesday | 9 | 9 |
| Wednesday | 9 | 9 |
| Thursday | 9 | 9 |
| Friday | 8 | 0 |
| Total | 44 | 36 |
The 44 and 36 figures describe calendar-week buckets in this illustration. They do not decide overtime, payroll workweek boundaries or the legal suitability of the arrangement. Those settings must be established separately for the actual workforce.
Anchor the calendar to a known workday
Choose a confirmed Monday that starts week one. Copy the entire 14-day pattern forward, rather than treating every month as a fresh cycle. A new month may begin in week two. Resetting the pattern at the first of the month can move an employee's day off and change the hours.
Include start time, end time and excluded breaks for each day. Nine net hours with a half-hour excluded meal require a 9.5-hour span. A calendar containing only the label “nine-hour day” leaves that detail unresolved.
Stagger teams and test Friday coverage
If two groups take alternating Fridays off, the organization may retain some Friday availability every week. Count the people and skills remaining on each Friday. Half the team being present is not sufficient if the service requires more than half the normal capacity or a specialist is absent.
Also test the shorter eight-hour Friday against the service window. Coverage may fall before the service closes even on a working Friday. Compare exact intervals, not just whether the date is marked as a workday.
Handle exceptions without shifting the whole cycle
Record a closure, leave day or temporary swap as an exception to the underlying calendar. Keep the original cycle visible so future dates remain predictable. If the organization deliberately restarts a pattern, record its new anchor date and effective date rather than silently changing the old schedule.
The OPM handbook illustrates a 5/4-9 compressed plan. This page uses comparable two-week arithmetic as a planning example, without extending federal employment rules to other workplaces.
Frequently asked questions
Does every month contain the same number of days off?
No. The calendar follows a 14-day cycle, while months have different lengths and starting weekdays. Count dates from the actual anchor.
Can I estimate monthly hours as 40 times four?
That gives only 160 hours and treats a month as four weeks. Use the dated schedule to calculate the actual monthly allocation.
Related calculators and guides
- Rotating Shift Calendar
- Shift Coverage & Gap Calculator
- Monthly Work Hours: Actual Calendar vs. 173.33-Hour Average
Explore more in Shift Schedules Calculators and Guides.