Quick Answer
The Bradford Factor is calculated using the formula B = S² × D, where S is the number of separate absence spells and D is the total number of days absent. The formula deliberately weights the number of spells more heavily than total days, so several short absences score higher than one long illness, because frequent short absences are considered more disruptive to a workplace.
What is the Bradford Factor?
The Bradford Factor is a formula UK employers use to measure how disruptive an employee's sickness absence has been over a rolling period, usually the last 12 months. It was developed at Bradford University's School of Management in the 1980s, originally to study the cost of absenteeism, and it has since become one of the most widely used absence management tools in UK HR departments.
What makes it different from simply counting sick days is that it doesn't treat all absence the same. A person who takes one two-week block off with flu scores very differently to someone who takes five separate one-day absences adding up to the same total. The Bradford Factor is built specifically to catch the second pattern, because short, frequent, unplanned absences tend to cause more disruption to rotas, cover arrangements and team planning than a single predictable block of leave.
The Bradford Factor formula explained
The formula is:
B = S² × D
Where S is the number of separate spells of absence in the reference period, and D is the total number of days absent across all of those spells.
Here's a worked example. Say an employee has had four separate absences in the last 12 months, totalling 12 days off in total. S = 4 and D = 12.
B = 4² × 12 = 16 × 12 = 192
Now compare that to someone who was off sick once for 12 days straight, a single spell covering the same total number of days. Here S = 1 and D = 12.
B = 1² × 12 = 1 × 12 = 12
Same number of days off. Wildly different scores. That gap is the entire point of the formula, you can check your own figures instantly with our Bradford Factor calculator.
Why does the formula weight short absences so heavily?
Squaring the number of spells is what does the work here. Because S is squared and D isn't, adding one more separate absence has a much bigger effect on the score than adding one more day to an existing absence.
The logic behind this is about predictability and disruption. A manager can plan around someone being off for two weeks, cover can be arranged, work can be reallocated in advance, and colleagues know what to expect. Five one-day absences scattered across the year are much harder to plan for. Each one is a fresh disruption: last-minute cover, delayed work, and colleagues repeatedly picking up the slack. The Bradford Factor was designed to put a number on that difference rather than treating all absence days as interchangeable.
What do different Bradford Factor scores mean?
There's no single official scale, trigger points are set by each employer in their absence management policy, not in statute, though Acas's guidance on absence trigger points notes that most organisations combine the frequency and length of absences when deciding when to act. Most UK organisations that use the Bradford Factor work within broadly similar bands:
| Bradford score | Typical treatment |
|---|---|
| Below 50 | Acceptable: low concern, unlikely to trigger any formal action |
| 50–199 | Monitor informally: return-to-work conversations and attendance discussions |
| 200–499 | Formal warning territory, a formal verbal or written warning stage |
| 500 and above | Serious concern: final warning or a formal capability process |
These bands are employer policy, not law. Every employer that uses the Bradford Factor should set out its own trigger points clearly in a written absence policy, and apply them consistently, because inconsistent application is one of the most common grounds for a successful unfair dismissal claim.
What happens when your Bradford score is too high?
Crossing a trigger point doesn't mean automatic dismissal, and any employer that treats it that way is exposing itself to legal risk. What it should trigger is a process: typically a return-to-work interview after each absence, and then, if the pattern continues, a formal meeting to discuss the underlying cause.
A high Bradford score is a prompt to have a conversation, not a verdict. There are often legitimate reasons behind a high score, a disability, a pregnancy-related condition, a temporary personal crisis, or a chronic health condition that comes and goes in short bursts. UK employers have a legal duty under the Equality Act 2010 to consider reasonable adjustments where absence is linked to a disability, and Bradford Factor scores should never be applied mechanically without that context.
Bradford Factor for part-time workers
The Bradford Factor formula itself doesn't adjust for part-time hours, it's based on the number of spells and days absent, not hours or contracted days per week. This means a part-time employee who works three days a week and takes four separate one-day absences gets exactly the same score as a full-time employee with the same pattern, even though the part-time employee has missed a larger proportion of their scheduled working time.
Some employers build their own adjustment into their policy, for example, prorating trigger points for part-time staff, or measuring absence as a percentage of scheduled days rather than relying on the raw Bradford score alone. If you're a part-time employee concerned about how your score is being applied, it's worth checking your employer's specific absence policy rather than assuming the standard bands apply unmodified.
Is the Bradford Factor fair?
It's a genuinely contested question in HR circles, and it's worth going in with a balanced view rather than treating the formula as gospel.
In its favour: it's simple, transparent, and gives managers an objective starting point rather than a purely subjective judgement about who "seems to be off a lot." It also correctly identifies that scattered short absences usually do cause more day-to-day disruption than a single block.
Against it: the formula makes no distinction between absence that's genuinely avoidable and absence caused by a disability, a chronic condition, pregnancy complications, or a family emergency. Two employees can hit the same score for very different reasons, and a policy that applies triggers mechanically without looking at the individual circumstances risks both unfairness and legal exposure. For that reason, most HR guidance, including Acas's own advice on managing absence and returning to work, treats the Bradford Factor as one input into a wider conversation, not a decision-making tool on its own.
If you're managing absence in your team, our Statutory Sick Pay calculator is a useful companion, it shows exactly what an employee is entitled to during a period of sickness, separate from any disciplinary process. Our guide to the SSP rate for 2026/27 covers the qualifying rules in more detail.
Frequently asked questions
What is a good Bradford Factor score?
Anything below 50 is generally considered low risk and unlikely to trigger formal action under most UK absence policies, though the exact threshold varies by employer.
Does the Bradford Factor include paid annual leave?
No. It only counts sickness absence, not booked holiday, statutory leave such as maternity or paternity leave, or authorised time off for other reasons.
Can I dispute my Bradford Factor score?
Yes. If you believe absences have been miscounted, or that the score doesn't reflect a legitimate reason such as a disability, you should raise this with HR or your manager. Most formal absence policies include a right of appeal at each stage.
Is the Bradford Factor a legal requirement?
No. It's a management tool some employers choose to use, there's no UK legal requirement to use it, and plenty of employers manage absence with other methods such as simple day-count triggers or the Bradford Factor's less aggressive variants.
How far back does the Bradford Factor calculation go?
Most employers use a rolling 12-month period, so absences older than a year drop out of the calculation automatically as new ones are added. The exact reference period should be set out in your employer's absence policy.
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