How Many First Aiders Does a 24/7 Team of 20 Need?
A 24/7 team of 20 in four crews needs two first aiders per crew, eight in all, and still runs about 17.5 shifts a year without one.
Eight, as two per crew, and that still leaves about 17.5 of the 1,095 shifts in a year without a first aider present. Round-the-clock cover changes the question: it is not how many first aiders the team has but how many each crew has, because the night crew cannot borrow a holder who is asleep. Four crews of five with two holders each cover 98.4 percent of shifts; three per crew, twelve in all, cover 99.8 percent and leave about 2.2 shifts a year uncovered.
Each extra holder, and what it buys
The rule says 1 first aider present on every shift. Each holder is absent on about 12.6 percent of rostered shifts. This is how many shifts a year fall short at each holder count, per crew, added across all 4 crews.
Holding exactly 1 is a coin flipped every shift. The first spare holder removes most of the exposure; the second removes most of what is left. On these assumptions, 4 holders per crew bring the expected shortfall to one shift a year or fewer, and 5 to one a decade.
How many are actually present
With 2 holders on each crew, the average shift has 1.75 present. Averages do not break rosters; the shifts with fewer than 1 do. Across 3 shifts a day, every day (1095 shifts a year), this is how the year is expected to distribute.
What is hard about this one
The mistake on a 24/7 site is to count first aiders across the whole team. Twenty people, four first aiders, one in five, sounds generous, and it is one per crew, which is the one-for-one coin flip on every shift: with one holder per crew the site is uncovered on about 138.4 of the 1,095 shifts in a year. The crew is the unit. A holder on the day crew does nothing for the night crew, and the cover arithmetic has to be run four times, once per crew, and then added up.
Two per crew is where most sites land and it is a reasonable place: each crew is uncovered only when both of its holders are off the same shift, which across four crews and 1,095 shifts comes to about 17.5 shifts a year. Three per crew, twelve holders in a team of twenty, is more than half the team and takes the expected gap to 2.2 shifts. The reason three per crew is rarer than it should be is not the training cost but the rotation: crews change, people move between them, and a crew that had three holders in January can have one by June without anybody deciding to reduce cover.
That drift is the real exposure on a rotating site, and the model cannot see it. The 17.5 shifts assume every crew keeps its two holders all year. In practice a leaver, a transfer or a lapsed certificate drops one crew to a single holder, and from that point that crew runs at the one-for-one rate, about 34.6 uncovered shifts a year on its own, until someone notices. Sites that hold cover on 24/7 rotations do so by making the per-crew count visible on the roster itself rather than on a training record in another system.
Move the requirement, move the answer
The holder count is usually the thing being argued about. The requirement itself is the other lever, and it is worth knowing what the same 2 holders per crew buy if the rule were one looser or one stricter.
| Required present | Covered | Short shifts a year |
|---|---|---|
| 1this page | 98.4% | 17.5 |
| 2 | 76.3% | 259.4 |
What this assumes, and where it is generous
These figures treat each holder as independently likely to be absent, which is the assumption most favourable to the roster. Holders are rarely independent: the two people who did the course together take the same school holidays, a certificate that lapses removes someone for the weeks it takes to rebook, and the person who is always asked to cover is the one most likely to be off sick. Treat every number here as the best case.
Only a valid certificate counts. A holder whose certificate has lapsed is a zero in this arithmetic for as long as the renewal takes, so the practical holder count is often one lower than the roster believes, and the row above the one you planned for is the one you are actually living on.
The absence share is 25 days of paid annual leave and 8 days of average sickness per person across 261 working days, which is 12.6 percent of rostered shifts. Both inputs vary by country; the relief factor library carries sourced figures for 17 of them. Swap your own in and the shape of the ladder holds even as the counts move. Because the operation runs fixed crews, the arithmetic is done per crew and added up: a holder on another crew is not on this shift.
What to do with this
Count first aiders per crew, never per team. One per crew is a coin flip on every shift, about 138.4 uncovered shifts a year; two per crew brings that to 17.5.
Re-run the per-crew count every time someone moves crew, leaves, or lets a certificate lapse. Cover on a rotation drifts downward without anyone deciding it.
If the site can justify three per crew, it buys 99.8 percent covered shifts and about 2.2 uncovered a year, and it means no crew is ever one absence from empty.
How long the certificate itself stays valid, and how it is renewed: Betrieblicher Ersthelfer (DGUV) (Germany, every 2 years).
The holder count on this page only works if it is the count of people whose certificate is valid today. Keeping that record current, who holds what, at which level, and until when, is what the Skills tab in Soon is for.
Common questions
- How many first aiders does a 24/7 team of 20 need?
- Two per crew as a floor, which for four crews is eight people. That covers a first aider on about 98.4 percent of shifts, leaving roughly 17.5 of the 1,095 shifts in a year uncovered. Three per crew, twelve in total, covers 99.8 percent. The total matters less than the per-crew count, because holders on other crews are not on site.
- Why not just count first aiders across the whole team?
- Because a first aider on the day crew is not present on nights. Four first aiders in a team of twenty sounds like one in five, but if that is one per crew, each crew is uncovered whenever its one holder is away, about 12.6 percent of shifts, which is 138.4 uncovered shifts a year across the site.
- What happens when someone moves crew or leaves?
- The crew they leave drops a holder, and if it falls to one, that crew alone runs at about 34.6 uncovered shifts a year until the gap is filled. Rotating sites lose cover this way far more often than through training budgets, which is why the per-crew count needs to live on the roster rather than in a training log.
Other qualifications
1 required, 2 held
How Many First Aiders Does a Team of 8 Need?1 required, 1 held
How Many First Aiders Does a Team of 40 Need for Two on Site?2 required, 4 held
How Many German Speakers Do You Need for Three on Every Shift of 10 Agents?3 required, 6 per crew
Your next schedule could take 2 minutes.
Import your team, set your rules, hit auto-fill. Most teams are live the same day.
30 days free ยท No credit card required
Already have an account?Sign in
