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4/10 and 9/80 Schedules: How to Total the Hours

By Frame Sixty Labs · Last updated: September 25, 2026

What do 4/10, 9/80 and the other compressed schedules add up to?

A compressed schedule fits a full-time week into fewer, longer days. The name tells you the pattern: 4/10 is four days of ten hours; 9/80 is nine working days that add up to 80 hours over two weeks. Here is how the common ones compare with a standard five 8s, counting paid hours only (unpaid lunches excluded):

Every schedule except 3/12 lands on 80 hours per two weeks. The difference is where those hours fall, and that matters because overtime in the US is generally counted per workweek, not per pay period. (Three 12s are common in hospitals; our guide for nurses and shift workers covers them.)

How do you total the hours on a compressed schedule?

1. Find out exactly when your workweek starts. A workweek is a fixed, recurring block of 168 hours. It doesn’t have to start on Sunday at midnight. On a 4/10 it usually matches the calendar week; on a 9/80 it often starts partway through a Friday. Payroll or your handbook will say.
2. Total each day: clock-out minus clock-in, minus unpaid breaks. A 10-hour day with a 30-minute lunch means 10:30 between punches, for example 7:00 to 17:30. (See hours between two times and paid vs unpaid breaks.)
3. Add the days that fall inside each workweek, in H:MM, carrying every 60 minutes into an hour. On a split Friday, hours before the boundary go in one week and hours after it go in the next.
4. Compare each workweek to 40:00. Anything over is generally overtime under the federal weekly rule. Check for daily or contract rules too.
5. Convert to decimal and multiply by the rate. Minutes ÷ 60 gives the decimal part: :07 is 0.1167, :15 is 0.25.

Worked example: a real 4/10 week

On paper a 4/10 is 40:00 flat. Real punches never are. Here is a week at 7:00 to 17:30 with a 30-minute unpaid lunch, except Wednesday, when lunch ran 45 minutes:

Adding in H:MM: 10:04 + 10:08 = 20:12, + 9:40 = 29:52, + 10:15 = 40:07. That is 40 hours and 7 minutes, or 40.12 decimal hours (7 ÷ 60 = 0.1167). The decimal column is rounded per day for display; add the minutes, not the rounded decimals, and round once at the end.

At $22.00 an hour with time-and-a-half over 40:

• Regular: 40 × $22.00 = $880.00
• Overtime: 7 minutes at $33.00 an hour = $33.00 × 7 ÷ 60 = $3.85
• Total: $883.85

Why do long days make the decimal mistake worse?

Because on a 4/10 you are sitting right on the 40-hour line, so small errors decide whether overtime exists at all. Type those same daily totals into a phone calculator as if H:MM were a decimal and you get:

10.04 + 10.08 + 9.40 + 10.15 = 39.67

That reads as a short week with no overtime. The real total is 40:07. Wednesday alone is off by 16 minutes: 9:40 is 9.67 hours, not 9.40. Minutes are sixtieths of an hour, not hundredths — there’s a full explanation in why your phone’s calculator can’t add time.

How does a 9/80 schedule split the week?

A 9/80 typically runs like this over a two-week cycle, with 9-hour days of 7:30 to 17:30 (one-hour unpaid lunch) and an 8-hour Friday of 8:00 to 17:00 (lunch 12:00 to 13:00):

Both ways add up to 80:00. The difference is the weekly shape. Counted by calendar week, week A is 44 hours — 4 hours over 40. Moving the workweek boundary to noon on the working Friday puts the morning in workweek 1 and the afternoon in workweek 2, so each is exactly 40. The next workweek then starts at noon on week B’s Friday, which is a day off, so the pattern repeats cleanly.

That boundary isn’t cosmetic. At $25.00 an hour:

• Split workweek: 40 × $25.00 + 40 × $25.00 = $2,000.00
• Calendar weeks: week A is 40 × $25.00 + 4 × $37.50 = $1,150.00; week B is 36 × $25.00 = $900.00; together $2,050.00

The $50.00 gap is the overtime premium on those 4 hours (4 × $12.50). Generally, an employer can set the workweek to start on any day and hour, and can change it if the change is meant to be permanent — but it can’t be moved back and forth to dodge overtime. If you’re on a 9/80, it’s worth knowing which boundary your employer actually uses.

Can you check a 9/80 from the pay stub alone?

Not really. A biweekly stub that says 80.00 regular hours looks right under either arrangement. To check it, you need each workweek’s total, which means splitting that Friday at the boundary yourself. If you stayed late on week A’s Friday, the extra time lands in workweek 2 — after the boundary — and if that pushes workweek 2 past 40:00, the extra is generally overtime. Keeping your own record, split by workweek, is the only way to catch it. How to read a timesheet walks through the columns to look for.

What happens with holidays and time off?

Holiday and leave policies are usually written in hours, which gets awkward when your days are not 8 hours long. The common case: a Monday holiday falls on a 4/10 workday and the policy pays 8 holiday hours.

8:00 + 3 × 10:00 = 38:00 — 2 hours short of your normal 40.

Employers handle the gap differently: some pay the holiday at your scheduled 10 hours, some ask you to use 2 hours of paid time off, and some let you make up the time in the same workweek. The same logic applies to a sick day — on a 4/10 it takes 10 hours of leave, not 8. On a 9/80, a holiday on a 9-hour day or a regular day off raises the same question. Your handbook decides; the arithmetic just shows you what to ask.

Do compressed schedules change overtime?

Under the federal Fair Labor Standards Act, overtime for non-exempt employees is generally based on hours over 40 in a workweek, so a 10-hour day on its own doesn’t trigger it. A few states and many union contracts also have daily overtime rules, and some require specific steps before an employer can adopt a compressed schedule. If you’re in a place with daily overtime, your 9th and 10th hours may be treated differently. See how to calculate overtime for the general method.

Frequently asked questions

How many hours a week is a 9/80 schedule?

An average of 40, and 80 every two weeks: eight 9-hour days plus one 8-hour day. By calendar week it’s 44 and 36; with the workweek split halfway through the 8-hour Friday, it’s 40 and 40.

Do you get overtime on a 4/10 schedule?

Not for a normal week under the federal weekly rule, because 4 × 10:00 = 40:00. Time past 40:00 in the workweek is generally overtime, even a few minutes. Daily overtime rules in some states and contracts can change that.

How does a 9/80 schedule avoid overtime?

By starting the workweek in the middle of the 8-hour Friday, so 4 hours fall in each week: 36:00 + 4:00 = 40:00 twice. Without the split, week A is 44 hours and, at $25.00 an hour, the two weeks cost $2,050.00 instead of $2,000.00.

How do holidays work on a 4/10 schedule?

If the policy pays 8 holiday hours on a 10-hour day, the week is 38:00. Employers cover the 2 hours with PTO, make-up time, or by paying 10 holiday hours. Check your handbook.

How many days off a year does a 9/80 schedule give?

One extra day every two weeks — about 26 a year before any overlap with holidays — for the same total hours as a standard schedule.