How many employees do you need to cover 24/5 with 8-hour shifts?

Twenty-four hours a day from Monday through Friday is 120 coverage hours a week. Cut that into 8-hour pieces and you get 15 shifts: a day shift, a swing shift, and a night shift, five days running. Divide 120 hours by a 40-hour target week and the result is exactly 3.0 FTE. Three employees, one per shift lane, each at exactly 40 hours. Few coverage problems divide this cleanly, which is precisely why this one is deceptive.

The clean fit is the trap. Exactly 3.0 FTE means the roster carries zero spare hours. When one of the three calls in sick, there is nobody to pull from: the other two are already committed to 40 hours in their own lanes, so the gap becomes overtime for someone coming off a shift, or it becomes eight uncovered hours. A roster that only works when nothing goes wrong is not a plan, it is a bet.

The staffing options are short. Two people means 60 hours each, which is over the EU Working Time Directive's 48-hour average weekly cap and not worth modeling further. Three means the standard 40-hour week with zero slack. Four brings everyone down to 30 hours of coverage work, which reads as expensive until the first absence, the first vacation request, and the first resignation notice. Most teams that intend to run 24/5 for more than a quarter end up at four.

With three people, the absence math is unforgiving. The natural cover for a missing swing shift is whoever worked the day shift, and that cover means two 8-hour shifts back to back. In the EU this collides with the required 11 hours of daily rest between shifts: a double that runs day into swing ends at midnight and leaves less than 11 hours before the next morning's shift. The honest options are a rule-breaking double, a dark lane, or the manager covering it personally. Most three-person 24/5 rosters quietly run on the third option.

Three people also means the three shift lanes are permanent, not rotating. Whoever holds the night lane works nights every working week with no rotation to relieve them, and the swing person is out of the house every weekday evening. There is no fair way to rotate three people through three lanes without constantly resetting sleep schedules, so most rosters this size freeze the assignments and accept the churn risk in the night lane. Vacations make it visible: when the night person takes a week off, one of the other two has to flip to nights and back.

The weekend shutdown is the one structural gift of 24/5, and it still needs managing. Friday's last shift hands over to nobody, so open incidents and half-finished work close into a written log instead of a conversation. Monday's first shift reopens from that log plus two days of accumulated alerts and tickets, which makes Monday morning the heaviest slot of the week. Decide deliberately where the week starts: if coverage opens with the early Monday hours, the night-lane employee clocks in at the Sunday-to-Monday boundary, and their weekend is shorter than the roster implies.