Common shift patterns, explained

Shift patterns have names, and the names are used as though everybody knows them. Here is what each actually means, in the order you are most likely to meet them.

Three 12s

Shape: three 12-hour shifts a week, usually 07:00–19:30 or 19:00–07:30. Where: hospitals, almost universally, for nursing.

Three days on and four off sounds excellent, and is — with two caveats. The half-hour either side for handover means a 12 is really a 13. And which three days moves, because most nursing rotas are self-scheduled then reconciled against what the ward needs.

At home: the days off are real and genuinely good. The unpredictability of which days is what makes childcare a weekly negotiation.

24 on, 48 off

Shape: a full 24-hour shift, then two days off. A three-day cycle. Where: fire services, some EMS.

Beloved by the people who work it, because two-thirds of your life is off-duty. The catch is arithmetic: a three-day cycle against a seven-day week means your working days walk through the calendar and never land on the same weekday twice running.

At home: nobody can predict it without counting. “Are you on this weekend?” becomes a question asked several times a week.

48/96

Shape: two 24-hour shifts back to back, then four days off. A six-day cycle. Where: increasingly common in fire services.

Two days at work, four at home. The four-day block is long enough to be a real break rather than recovery, which is why crews tend to prefer it.

At home: better than 24/48 for planning, because the off-block is long enough to hold a trip. Still walks through the week.

The Kelly schedule

Shape: on, off, on, off, on, then four off. A nine-day cycle. Where: fire services, mainly in the US.

Averages a 56-hour week. The nine-day cycle is the least predictable of the common patterns from outside — nine and seven share no factors, so it takes nine weeks to return to the same weekday alignment.

At home: effectively impossible to hold in your head. This is the pattern most likely to make family give up trying and just ask.

Pitman (2-2-3)

Shape: two on, two off, three on; then two off, two on, three off. A fourteen-day cycle. Where: dispatch centres, security, manufacturing, some policing.

The great virtue: it is a fortnightly cycle, so it lines up with the calendar. Every other weekend is fully off, permanently, and you always know which.

At home: the most family-legible of the rotating patterns. “Every other weekend” is something people can actually retain — though which one still needs looking up.

DuPont

Shape: four nights on, three off; three days on, one off; three nights on, three off; four days on, seven off. A four-week cycle. Where: continuous manufacturing, chemical plants, refineries.

Contains a full seven-day break every four weeks, which is the reason people put up with the rest. Also rotates between days and nights within each cycle, which is the hard part.

At home: the seven-off is a genuine holiday and worth planning around. The rest of the cycle is dense and hard to follow from outside.

Four tens

Shape: four 10-hour days, three off. Not usually rotating. Where: warehousing, logistics, some manufacturing and public sector.

A compressed week rather than a rotation. Three days off every week, at the cost of long days.

At home: if the three days are fixed, this is one of the easiest to live with. If they move by coverage need, it inherits the usual problem.

Rotating watches

Shape: blocks of days, then evenings, then nights, changing every few weeks. Where: policing, some healthcare and security.

The classic rotating shift. Hardest of all on sleep, because your body is asked to reset several times a cycle.

At home: everything your family learned last month is wrong this month, which is uniquely exhausting for both sides.

The pattern behind the patterns

Two things predict how hard a rotation is on the people around you, and neither is the hour count.

Cycle length against seven. A pattern whose cycle shares a factor with the week (Pitman’s fourteen, a fixed four-on-three) stays legible. One that does not (three, eight, nine) walks through the calendar and becomes unpredictable from outside, however regular it is on paper.

Whether time-of-day rotates. Working the same hours on moving days is a logistics problem. Moving the hours as well adds a physiological one, and the recovery days that come with it are not really days off.

If you are trying to explain your rota to someone, those are the two things worth explaining first — and then showing them the actual days, because no amount of explaining a nine-day cycle helps somebody answer whether you are around on the 14th.