Practical guide

4 On, 4 Off: Hours, Weekends and Calendar Drift

Four on, four off repeats every eight days. At twelve hours per workday, it averages 42 scheduled hours per seven-day week.

By Intious · Updated September 7, 2026

Quick answer

Four on, four off repeats every eight days. At twelve hours per workday, it averages 42 scheduled hours per seven-day week.

Why weekdays move

An eight-day cycle is one day longer than a calendar week. A work block therefore starts on a different weekday each cycle. A fixed Monday-to-Sunday template cannot represent the rotation indefinitely.

Calculate scheduled hours

Four twelve-hour shifts total 48 hours in eight days. The weekly average is 48 ÷ 8 × 7 = 42 hours. For an actual pay period, count its workdays and multiply by shift length rather than multiplying this average by an arbitrary number of weeks.

Plan leave using your calendar

Count the workdays inside the requested absence. Eight consecutive calendar days may contain only four scheduled shifts. PTO policy determines how many paid hours are charged; a calendar-day count alone does not.

Try it with your numbers

Generate a dated work/rest rotation and download an all-day calendar.

Rotating Shift Calendar

Next steps

Calculation limitations · Report a correction

Frequently asked questions

How many hours are in one full cycle?

Four 10-hour shifts give 40 hours per eight-day cycle; four 12-hour shifts give 48. Multiplying by 7/8 converts either to a long-run weekly average.

Can I multiply 42 by 52 for an exact annual total?

No. That is a rough annualized comparison, not a dated count. A calendar year and its partial cycles must be counted from the actual anchor date.

Do four 12-hour shifts mean a 48-hour average week?

They total 48 hours per eight-day cycle. The long-run seven-day average is 48 × 7 ÷ 8 = 42 hours; individual calendar weeks can differ.

Check the assumptions against the Rotating Shift Calendar and keep the inputs alongside your result. For a discrepancy, send an anonymous worked example rather than private employee records.

Explore more in Shift Schedules Calculators and Guides.