9/80 work schedule
Eighty hours in nine days instead of ten, buying every other Friday off. The calendar is easy; the payroll rule underneath it is not.
Also known as: 9-80 schedule, nine eighty, 5/4-9 compressed schedule, every other Friday off
- Shift length
- 9h
- Rotation cycle
- 14 days
- Teams
- 1
- Avg hours/week
- 40
- Longest stretch
- 5 days
- Longest break
- 3 days
The full 14-day rotation
One complete cycle. Coverage is 5 business days week one, 4 week two: deliberately not every day, which is the shape of this pattern rather than a gap in it.
| Team | Week 1 | Week 2 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Everyone | D | D | D | D | D | D | D | D | D | |||||
- The row shows the full two-week cycle: five days on (the Friday is 8 hours, the rest 9), a weekend, four days on, then a three-day weekend.
- The worked Friday is the hinge of the whole pattern: for overtime purposes its first 4 hours close one workweek and its last 4 open the next.
- Offices usually split staff into A and B groups with alternating Fridays off, so the building never goes fully dark. Read the second group as this row shifted by one week.
Build your 9/80 calendar
Pick the date your rotation starts (day 1 of the grid above) and a team to see the next six weeks as real dates. Download the result for your calendar app or as a spreadsheet.
Calendar exports cover 26 weeks from the start date. Shift times use this page's defaults and can differ from your operation's clock times.
How the 9/80 schedule works
The 9/80 compresses two standard weeks, 80 hours, into nine working days: four 9-hour days plus one 8-hour Friday in week one, then four 9-hour days in week two with the Friday off. Everyone gets 26 three-day weekends a year without giving up any hours or pay.
What separates the 9/80 from every other compressed week is a payroll technicality that decides whether it works at all. Under the FLSA, overtime is owed past 40 hours in a fixed workweek. Count naively from Monday and week one contains 44 hours, which means 4 hours of overtime every other week, forever. The fix is to define the workweek as starting mid-shift on Friday, exactly 4 hours in: the worked Friday then splits 4 hours into each adjacent week, and both weeks land on precisely 40.
That split is not optional paperwork, it is the schedule. Get it wrong and the 9/80 quietly costs 5 percent more in wages than the five-day week it replaced. Get it right and the schedule must then be defended: the workweek definition has to be fixed, documented, and applied consistently, and taking a vacation day on the split Friday creates edge cases that payroll needs rules for.
How many people you need
Staffing one position across this pattern's window (5 business days week one, 4 week two) takes one person on the schedule shown, before you cover holidays, sick leave, and training. A planning buffer of around 25 percent on top is a realistic starting point; the exact number depends on your absence rates, which you can work out with our shrinkage calculator. The same worked arithmetic for other coverage windows and team sizes lives in the staffing math library.
| Positions per shift | Minimum headcount | With 20% shrinkage buffer |
|---|---|---|
| 1 | 1 | 2 |
| 2 | 2 | 3 |
| 3 | 3 | 4 |
| 5 | 5 | 7 |
| 10 | 10 | 13 |
Pros and cons of the 9/80 schedule
Works in its favor
- Twenty-six three-day weekends a year at zero change in total hours or pay
- Nine-hour days are a far gentler stretch than the 4-10โs ten, so the fatigue cost is modest
- Alternating A and B Fridays keeps the office covered every business day, unlike a plain 4-10
- Popular enough in engineering, aerospace, and government that candidates actively search for it as a perk
- One fewer commute every other week with barely perceptible daily change
Watch out for
- The FLSA workweek must be split mid-Friday, exactly 4 hours into the shift, or week one owes 4 hours of overtime every cycle
- The workweek definition has to be fixed and documented before the first cycle, not repaired after an audit
- Vacation, sick time, and holidays landing on the split Friday create payroll edge cases that need written rules
- California and other daily-overtime states require a formal alternative workweek election, since 9 hours crosses the 8-hour daily line
- Half the team is always missing on any given Friday, which frustrates cross-team scheduling and customer response
Who runs 9/80
Aerospace and defense
The 9/80 is close to standard among large US aerospace employers, where it doubles as a recruiting perk.
Engineering firms
Salaried project work absorbs the 9-hour day easily, and the alternating Friday maps neatly onto client coverage.
Government agencies
Federal compressed schedules (the 5/4-9 variant) run the same arithmetic under their own regulations.
Corporate offices
A common flexible-work offering where full remote is off the table: the calendar changes, the headcount math does not.
Whichever industry you plan for, the hard part is rarely the pattern itself but keeping it fair as people join, leave, and swap. That is worth reading up on before you commit a team to one; our guide on making shift schedules fair covers the rotation-fairness tradeoffs in depth.
Common variations
- 5/4-9 (federal)
- The US federal compressed variant: eight 9-hour days, one 8-hour day, one day off per pay period. Same math, different rulebook.
- A/B Friday groups
- Half the office takes week-one Fridays, half week-two. Coverage never drops to zero, and conference rooms empty out on both.
- 9/80 with Monday off
- Identical arithmetic with the split day moved. Rarer, because the three-day weekend loses its Friday-evening head start.
Compare with other patterns
4-10 work schedule (four tens)
Four 10-hour days, three days off, every week. The same 40 hours compressed into fewer, longer days, at the price of one dark weekday.
10h shifts · 7-day cycle · longest stretch 4 days
View pattern →4-on-3-off shift pattern
Four days on, three days off, the same days every week. Two squads cover all seven days, and the arithmetic leaves exactly one day where both are in.
10h shifts · 7-day cycle · longest stretch 4 days
View pattern →2-2-3 schedule (Panama)
Four teams on 12-hour shifts work 2 days, get 2 off, work 3, in a 14-day cadence that gives every team a full weekend off every other week.
12h shifts · 28-day cycle · longest stretch 3 days
View pattern →Frequently asked questions
- How does overtime work on a 9/80 schedule?
- The workweek is redefined to start halfway through the worked Friday, exactly 4 hours into the shift. That splits the Friday between the two weeks so each contains exactly 40 hours, and no overtime is owed under the FLSA. Without that split, counting Monday to Sunday, week one holds 44 hours and 4 of them are overtime every other week.
- Is a 9/80 schedule legal in California?
- Yes, but not casually. California owes daily overtime past 8 hours, and a 9/80 runs 9-hour days, so it requires a formal alternative workweek schedule adopted by secret-ballot election of the affected work unit and registered with the state. Skip the election and every ninth hour is time-and-a-half.
- What happens when a holiday lands on the split Friday?
- This is the edge case that tests whether the 9/80 was set up properly. The worked Friday belongs half to each workweek, so holiday pay, vacation deductions, and sick time on that day have to be split or assigned by a written rule. Employers that never wrote the rule discover the problem in their first wage audit.
- What is the difference between a 9/80 and a 4-10?
- Both average 40 hours with extra days off, but they distribute the compression differently. The 4-10 takes a full day off every week at the cost of 10-hour days and a permanently dark weekday. The 9/80 takes a day off every other week, keeps daily hours at a gentler 9, and preserves five-day coverage in week one, paying for it with the workweek-split payroll rule.
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