What Is the Bradford Factor? How to Calculate and Use Bradford Scores Fairly
It's 6:40 a.m., and the same team member has just texted in sick again. It's their third single-shift absence this quarter, and the 7 a.m. opening still needs covering. You want to know if this is a pattern or bad luck, and how to measure it fairly.
The Bradford Factor is an absence score built for exactly that question. It's commonly calculated as S² × D over a rolling 52 weeks. S is the number of separate absence spells, and D is the total days absent. You'll also hear it called Bradford points or a Bradford score.
Absence adds up across the UK, and the Office for National Statistics (ONS) tracks it. The latest ONS sickness absence figures estimate that 148.8 million working days were lost because of sickness or injury in 2025. That's an average of 4.4 days lost per worker.
Keep one idea in mind: the score is a flag, not a verdict. It shows how often someone's absence breaks the rota. It can't tell you why.
What the Bradford Factor measures and why spells matter more than days
The Bradford Factor measures how often someone is absent, as well as how long. Because the formula squares the number of spells, frequent short absences score far higher than one long absence.
The premise is that repeated short absences can disrupt a team more than one long, planned absence. Acas, the Advisory, Conciliation and Arbitration Service, also distinguishes between the two types of absence. See how Acas suggests recording absence: a single long-term absence with a clear reason should be treated differently to repeated short-term absences. A run of single-day sick calls hands you a fresh gap each time, with little notice.
In shift work, every spell is a separate hole in the rota. Each one can mean a phone round, a supervisor staying late, or a short-staffed floor at the busiest hour. Here's what workplace absenteeism means for the bigger picture.
Everyday illness plays a big part. The same ONS data shows minor illnesses were the most common reason given for sickness absence in 2025, accounting for 30.4% of occurrences. Coughs, colds, and stomach bugs are real, which is why the number needs a conversation behind it.
How to calculate a Bradford Factor score
You need two numbers from your absence records: separate spells and total days or shifts missed. Square the first, multiply it by the second, and that's the whole Bradford Factor calculation.
The formula: S² × D
The Bradford Factor formula is B = S² × D. Here's what each letter stands for:
S is the number of separate absence spells
D is the total days (or shifts) absent across those spells
B is the Bradford score
It's commonly applied over a rolling 52 weeks, so older spells drop out as time moves on. Follow three steps:
Count the separate spells in the last 52 weeks
Square that number by multiplying it by itself
Multiply the result by the total days or shifts absent
Want a quick Bradford Factor calculator? In Excel or Google Sheets, put spells in column B and total days in column C. Then type =B2^2*C2 into column D and copy it down for each person.
Worked examples: same days, very different scores
The table shows how the spell count drives the score. Watch the last column.
Absence pattern | Spells (S) | Total days (D) | Calculation | Bradford score |
|---|---|---|---|---|
A single 10-day absence | 1 | 10 | 1² × 10 | 10 |
Two absences, five days in total | 2 | 5 | 2² × 5 | 20 |
5 absences, 10 days in total | 5 | 10 | 5² × 10 | 250 |
10 single-day absences | 10 | 10 | 10² × 10 | 1,000 |
The first and last rows both lose 10 days. The last one scores 100 times higher, because the rota broke 10 times instead of once. That difference is the flag.
Here's how it looks in a café. Priya's absence record covers the last 12 months. In that time, they've had four single-shift absences, so their score is 4² × 4 = 64.
Two of those were the 7 a.m. opening, so the supervisor opened the doors, set up the coffee machine, and served the first queue alone. The other two were Saturday closes, which ran one person down through the evening rush.
Their colleague Tom was off for 10 consecutive shifts after planned surgery. Tom's score is 1² × 10 = 10. You knew the dates weeks ahead and built cover into the rota.
Tom missed more shifts, yet Priya scores more than six times higher. That tells you where to look. It doesn't tell you what's going on in Priya's life.
Counting spells in shift work
Decide your counting rules before you calculate anything, and write them into your policy. Without them, two managers can score the same absence record differently.
Shifts or calendar days. Pick one unit for D and use it for everyone. For shift workers, missed shifts on the rota can give a fairer picture than calendar days.
Rest days in the middle. A sickness absence that runs across rest days counts as one spell. If you count in shifts, only the missed shifts on the rota add to D.
Going home sick mid-shift. Decide if this counts as a spell, a part-shift, or neither. Then record it the same way every time.
No-shows. A no-call, no-show may be a conduct matter. Decide if it adds to the score or goes through a separate process.
Part-time staff. Someone on two shifts a week has fewer shifts to miss. Check their score against contracted shifts before you act.
Use one window for everyone, whether you call it a rolling 52 weeks or a rolling 12 months. Logging each absence in leave management software against a set leave type helps keep reasons consistent across managers and sites.
You also need to know which shifts someone missed. Deputy Time and Attendance records clock-ins against scheduled shifts, so managers can review gaps before they count a spell.
Bradford score chart: a quick lookup grid
This Bradford score chart gives you the score at a glance. Find the number of spells on the left, then read across to the total days absent.
Spells (S) | 2 days | 5 days | 10 days | 15 days |
|---|---|---|---|---|
1 | 2 | 5 | 10 | 15 |
2 | 8 | 20 | 40 | 60 |
3 | 18 | 45 | 90 | 135 |
4 | 32 | 80 | 160 | 240 |
5 | 50 | 125 | 250 | 375 |
6 | 72 | 180 | 360 | 540 |
Some cells, such as six spells across two days, only apply if your policy counts part-shifts as part-days. Read down any column and you'll see the Bradford Factor scale climb fast. In the 10-day column, doubling the spells quadruples the score.
What's a good Bradford Factor score? Trigger points explained
There's no legal or official "good" Bradford Factor score. Acas guidance on trigger points says there are no legal rules about how or when absence should be reviewed. Employers set their own trigger points, so an acceptable Bradford score is whatever your policy says, applied the same way to everyone.
Acas also publishes free guidance on writing policies. Its Acas absence policy guidance says policies should consider "whether you use a trigger point system and how this works". If you use one, put the bands in writing so staff know where they stand.
Here's one illustrative set of bands to adapt for your business. Treat it as an example, since each employer sets its own.
Example trigger points (set by the employer, not a legal standard)
Bradford score | Example action |
|---|---|
Under 51 | No action |
51–200 | Informal conversation |
201–400 | First formal stage |
401–600 | Further formal stage |
601+ | Final review |
A trigger starts a review. It doesn't decide the outcome. When someone crosses a band, look at the reasons, the pattern, and any support they need first. The score raises the flag, and the conversation reaches the verdict, if there is one.
