What is the Bradford Factor formula?

The Bradford Factor is calculated as B = S squared multiplied by D, where S is the total number of separate absence occasions in a rolling 52-week period and D is the total number of days absent in the same period. For example, an employee who had 3 separate spells of absence totalling 10 days scores 3 × 3 × 10 = 90. The formula deliberately weighs frequent short absences more heavily than a single long illness because short, unpredictable absences are generally more disruptive to the workplace.

What Bradford Factor score triggers a formal review?

Threshold levels vary by organisation and there is no single legally mandated level. Common trigger points used in practice are: below 50 points (low concern, no formal action); 50 to 199 points (medium concern, informal discussion with manager); 200 to 399 points (high concern, written warning or formal review); 400 to 999 points (serious concern, final written warning); 1,000 points or above (very serious, may lead to dismissal proceedings). These are guidelines only. Employers must always consider the reasons behind any absence, including whether it relates to a health condition, disability, or family circumstances, and follow a fair process before taking disciplinary action.

Should I use the Bradford Factor alone to manage absence?

No. The Bradford Factor is a diagnostic tool to flag patterns that may warrant a conversation, not a substitute for fair and contextual management. A high score may simply reflect a period of genuine illness or a disability requiring a reasonable accommodation. Best practice is to use the score as a starting point for a supportive return-to-work conversation, review the reasons behind each absence, and consider factors such as whether the absences are covered by sick leave entitlements or relate to a protected characteristic. The Bradford Factor is not legally binding in New Zealand or elsewhere.

Bradford Factor Calculator

The Bradford Factor measures the disruptive impact of short, frequent absences versus a single long absence. Enter the number of separate absence occasions and the total days absent over a rolling 52-week period to calculate the Bradford Factor score and see which action band it falls into.

Formula: B = S² × D, where S = number of separate absence spells and D = total days absent.

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Reviewed June 2026 Standard Bradford Factor formula. Threshold bands are illustrative guidelines; set your own organisational policy.

1. Absence Data (rolling 52 weeks)

Number of separate absence occasions (S)

Total days absent (D)

2. Your Organisation's Trigger Points

Medium concern threshold (default 50)

High concern threshold (default 200)

Serious concern threshold (default 400)

Critical threshold (default 1000)

Bradford Factor Result

Absence Spells (S)

Separate occasions

Bradford Factor Score
90
B = S² × D

Total Days Absent (D)

Over 52 weeks

Bradford Factor Band

Low concern 0 to 49 No formal action; monitor only

Medium concern 50 to 199 Informal discussion with manager

High concern 200 to 399 Formal review or written warning

Serious concern 400 to 999 Final written warning

Critical 1,000+ Disciplinary proceedings may be considered

Calculation Breakdown

Separate spells (S)3

S squared (S²)9

Total days absent (D)10

Bradford Factor (S² × D)90

Scenario Comparison

1 spell, same total days-

Your result (S spells)-

Each spell = 1 day each-

Multiplier vs 1 spell-

Summary:

What Is the Bradford Factor?

The Bradford Factor is a human resources tool used to measure the impact of employee absences. It was developed at the University of Bradford's management centre and is based on the observation that frequent short-term absences are more disruptive to an organisation than a single long absence of the same total length. A manager can plan for an employee who is off for three weeks with a known illness; the same three weeks spread across six unpredictable one-day absences is much harder to cover.

The formula is: B = S² × D

Where B is the Bradford Factor score, S is the number of separate absence occasions in a 52-week rolling period, and D is the total number of days absent in the same period. Because S is squared, adding more spells increases the score exponentially even if the total days stay the same.

Worked Example

Using the default values: an employee had 3 separate absence spells totalling 10 days in the past year.

S = 3, so S² = 3 × 3 = 9
D = 10
Bradford Factor = 9 × 10 = 90

A score of 90 falls in the medium concern band (50 to 199), suggesting an informal discussion with the employee's manager is appropriate. By contrast, if those same 10 days were a single continuous absence (S = 1), the score would be 1 × 10 = 10, which is low concern. This illustrates how the formula penalises frequent short absences.

Common Bradford Factor Thresholds

Score Range	Typical Band	Suggested Response
0 to 49	Low concern	No formal action; routine monitoring
50 to 199	Medium concern	Informal discussion with line manager
200 to 399	High concern	Formal review or first written warning
400 to 999	Serious concern	Final written warning
1,000 and above	Critical	Disciplinary proceedings may be considered

These bands are illustrative and organisations should set their own thresholds in an absence management policy. Thresholds may differ by role (for example, a lower threshold for roles requiring physical presence) or industry.

Important Limitations

The Bradford Factor is a diagnostic aid, not a disciplinary shortcut. Before taking any action based on a high score, managers should investigate the reasons for each absence. Absences related to a disability, chronic condition, pregnancy, or other protected characteristic must be handled carefully. In New Zealand, the Employment Relations Act 2000 and the Human Rights Act 1993 require employers to consider reasonable accommodations and to follow a fair process. Dismissing an employee solely on the basis of a Bradford Factor score without proper investigation and process is likely to be challenged as an unjustified dismissal.

Best practice is to use the score as a trigger for a supportive, non-adversarial return-to-work conversation rather than immediate disciplinary action.

Related Calculators

Maths and Stats Calculators: hub for all maths and stats tools.
Absence Percentage Calculator: work out what percentage of scheduled time was lost to absence.
Annual Leave Calculator: calculate annual leave entitlements under the Holidays Act 2003.
Sick Leave Calculator: work out sick leave entitlements for NZ employees.

Method note: The Bradford Factor formula B = S² × D is the standard published formulation widely used in HR practice. Threshold bands are based on commonly cited industry guidelines and are not set by any NZ legislation. Organisations should define their own trigger points in a written absence management policy.

This calculator is for informational purposes only and does not constitute employment advice. Before taking action based on absence scores, employers should follow a fair process, consider the reasons for absence, and seek advice from an employment relations specialist where appropriate.