How Many of 5 Staff Can Be Off at Once?
One person can be away. The model expects the team to be short on about 32.1 of 261 working days, and growing to 6 or 7 makes that worse.
On a team of 5 that needs 4 people on shift, 1 person can be on leave at a time. With 25 days of paid annual leave and 8 days of average sickness each, the model expects the team to fall below its minimum on about 32.1 of the 261 working days a year, and 69.8 if the whole year ran at peak leave rates. Those counts assume people book leave independently of each other, so read them as a floor on the real risk rather than a forecast.
How often that many are actually away
The average is 0.63 people away, and averages do not break rosters. What breaks a roster is the tail: the days when more people than usual are off at the same time. With 5 people each away on 12.6 percent of working days, this is how a year of 261 days is expected to distribute.
Everything below 2 away fits inside the roster. Everything from 2 up is a day the operation runs under its minimum of 4, and those add up to about 32.1 days a year.
What is hard about 5
Headroom does not rise smoothly with headcount. It moves in whole people, and only when the team crosses a boundary, so expected short days saw-tooth rather than fall. Every team from 4 to 7 carries the same headroom of 1, and inside that run the bigger team is short more often, not less: about 21 expected short days at 4, 32.1 at 5, 44.3 at 6, and 57 at 7. A team of 5 sits on the second rung of that run. The fifth person is already paying the penalty of a body that added no cover, because the minimum on shift rose with the team while the buffer stayed at 1.
The arithmetic underneath is tight in a way the average hides. Each person is away on 12.6 percent of working days, which puts 0.63 people away on an average day and 1.01 in a peak leave period. Headroom is 1, so the typical peak day already spends the entire buffer before a single unplanned absence is counted, and at peak rates the short-day count works out at 69.8. Separately, the leave book alone is 125 person-days a year, and with never more than one person away at a time those days have to be placed one at a time into 261 working days. Sole occupancy of the calendar is the real constraint, not the annual total.
The way out is not the sixth hire. Moving from 5 to 6 raises expected short days to 44.3, and headroom only reaches 2 at a team of 8, where the count drops to about 18.1, so three hires buy what most managers assume one will. The cheaper lever is the minimum itself. Holding the operation on 3 instead of 4 gives headroom 2 and about 4.3 expected short days a year, and holding it on 2 gives headroom 3 and 0.3. Cross training one person far enough that the floor can sit at 3 does more for this roster than any hiring it can afford. And every figure here assumes absences are independent, which is the assumption most generous to the roster, since real leave clusters on school holidays and the last fortnight of December.
Move the minimum, move the answer
The team size is usually fixed. The minimum on shift often is not, and it is the faster lever: making one role coverable for a day changes the arithmetic more than a hire does.
| Minimum on shift | Can be away | Short days a year |
|---|---|---|
| 4assumed | 1 | 32.1 |
| 3 | 2 | 4.3 |
| 2 | 3 | 0.3 |
What this assumes, and where it is generous
These figures treat each person as independently likely to be away, which is the assumption most favourable to the roster. Real leave clusters: school holidays, the last fortnight of December, and the local summer shutdown pull requests onto the same dates. Treat every number here as the best case, and the peak column as a reminder of how far the real case sits from it.
Run the same team at a peak concentration of 1.6 times the ordinary rate, which is a stated planning assumption rather than a measured figure, and the expected count away rises from 0.63 to 1.01. Held across a full year, that rate would imply about 69.8 short days rather than 32.1. Real years are neither, but the gap between the two is the size of the scheduling problem that leave clustering creates.
The inputs are 25 days of paid annual leave and 8 days of average sickness per person. Both vary by country, and the relief factor library carries sourced figures for 17 of them, from zero statutory leave in the United States to 28 days in the United Kingdom. Swap your own numbers in and the shape of the distribution holds even as the counts move.
What to do with this
Approve one absence at a time and treat any overlapping second request as an exception that needs a named plan, because headroom on a team of 5 is exactly 1.
Before funding a sixth person, test whether the minimum on shift can drop to 3, since that moves expected short days from 32.1 to about 4.3 while a sixth hire moves them to 44.3.
Ration peak periods deliberately, because the model puts 1.01 people away on the average peak day against headroom of 1, and peak rates imply 69.8 short days a year.
Common questions
- How many of a team of 5 can be off at once?
- One. With a minimum of 4 people on shift, headroom is 1, so a single approved absence uses the whole buffer and any second absence drops the team below its minimum. Across 261 working days the model expects that to happen on about 32.1 of them, usually when a sick day lands on a date that already has someone on booked leave.
- Would hiring a sixth person fix it?
- Not for reliability. At 6 people the minimum on shift rises with the team, headroom stays at 1, and expected short days go up from 32.1 to 44.3. Headroom only reaches 2 at a team of 8, where the count falls to about 18.1. The sixth hire buys capacity and adds another leave allowance to place, but it does not buy cover.
- How much worse is the real risk than 32.1 days?
- Higher, and the model cannot say by how much. The 32.1 figure treats each person as independently likely to be away, which is the assumption most generous to the roster, while real leave clusters on school holidays and the last fortnight of December. Running the same team at peak leave rates implies 69.8 short days a year, which is the honest bracket for what clustering does to a headroom of 1.
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