What is the Bradford Factor?

The Bradford Factor (also called the Bradford Formula or Bradford Index) is a widely used HR metric that measures the impact of employee absences on an organisation. It was developed at the Bradford University School of Management and is based on the principle that frequent, short-term absences are more disruptive to a business than fewer, longer absences.

For example, an employee who takes ten separate single-day absences causes significantly more disruption than an employee who takes one ten-day absence. Each short absence requires last-minute cover, work redistribution, and management time — multiplied across every occurrence.

How the Bradford Factor formula works

The formula is:

B = S × S × D

B = Bradford Factor score

S = number of separate absence spells in a rolling 12-month period

D = total number of days absent in the same period

The critical detail is that S is squared. This means the number of separate absence instances has a much greater impact on the score than the total number of days. Two employees can have the same number of days off but wildly different Bradford Factor scores depending on how those days are distributed.

Worked example

Consider two employees who have both been absent for 10 days over 12 months:

Employee A — 1 absence spell of 10 days: 1 × 1 × 10 = 10
Employee B — 10 separate single-day absences: 10 × 10 × 10 = 1,000

Employee B scores 100 times higher despite the same total days absent. The Bradford Factor flags Employee B's pattern as far more disruptive.

How to use Bradford Factor scores

The Bradford Factor is a trigger tool, not a disciplinary tool. A high score should prompt a conversation, not an automatic penalty. Here is how most UK employers use it:

Set clear trigger points — define thresholds in your absence policy (see the table above) and communicate them to all staff.
Monitor over a rolling 12-month period — calculate scores using the previous 12 months, not the calendar year.
Investigate context — when an employee hits a threshold, have a supportive conversation to understand the reasons behind their absences.
Exclude protected absences — disability-related absences, maternity/paternity leave, and other legally protected absences should not be included in the calculation.
Apply consistently — use the same thresholds and processes for every employee to avoid claims of discrimination.

Limitations to be aware of

The Bradford Factor is a useful tool but it has limitations that every employer should understand:

Disability discrimination risk — employees with chronic conditions (e.g. migraines, IBS, endometriosis) may have frequent short absences that inflate their score. Under the Equality Act 2010, employers must make reasonable adjustments and should consider excluding disability-related absences.
No context — the formula treats all absences equally. A genuine flu and a suspicious post-weekend absence both count the same.
Presenteeism risk — employees aware of the formula may come to work while unwell to avoid triggering thresholds, which can spread illness and reduce productivity.
Not a standalone tool — the Bradford Factor should be one component of a broader absence management approach, never the sole basis for disciplinary action.

Best practices for UK employers

Document your policy — include the Bradford Factor, trigger thresholds, and the process that follows in your company absence policy.
Train managers — ensure line managers understand the formula, what scores mean, and how to conduct supportive absence conversations.
Use return-to-work interviews — pair the Bradford Factor with return-to-work interviews to get a fuller picture of absence patterns.
Automate the calculation — manual tracking in spreadsheets is error-prone and time-consuming. Leave management software calculates Bradford Factor scores automatically as absence records are updated.
Review thresholds annually — what works for a 10-person team may not suit a 100-person organisation. Review your trigger points as your business grows.