What is the Bradford Factor?

The Bradford Factor (BF) is an HR metric that weights frequent, short-term absences more heavily than occasional long absences over a review period (commonly a rolling 52 weeks). It is used as an internal trigger for review, not a legal threshold.

How is the Bradford Factor calculated?

Use the formula BF = S² × D, where S is the number of absence instances (spells) in the review period and D is the total number of working days absent in that period.

What counts as an “instance” of absence?

One continuous spell of sickness that begins and ends with a return to work. Multiple consecutive sick days count as one instance. If policy allows half-days, treat each spell consistently per policy.

Do weekends or non-working days count in D?

Count scheduled working days lost. Calendar days should not be used unless your policy explicitly defines absence that way.

What review period should I use—52 weeks or 12 months?

Many organizations use a rolling 52-week window. Others use fixed periods (12 months, 6 months, quarter). Choose one and apply it consistently.

How should I interpret the score?

Bands vary by employer. A common example is: 0–49 Low, 50–124 Moderate, 125–399 High, ≥400 Very High. Treat these as configurable triggers, not universal standards.

Does part-time work change the calculation?

The formula is the same. Count only the employee’s scheduled working days lost. Policies should clarify treatment of variable shifts.

What about disability-related or pregnancy-related absence?

Many policies adjust or exclude certain absences to ensure fairness and compliance with equality guidance. Apply your organization’s policy and document any adjustments.

Can the Bradford Factor be negative or fractional?

No. S and D are non-negative. If half-days are allowed, D can be fractional (e.g., 0.5). The score itself is non-negative and typically reported as an integer or one decimal place.

Why does a single long sickness give a lower score than many short ones?

The squaring of S (instances) is designed to emphasize disruption from frequent short absences, which BF treats as more operationally impactful.

Bradford Factor Calculator

Calculate the Bradford Factor (S² × D) to assess short-term absence impact over a chosen review period.

Review period

Most organizations use a rolling 52-week window.

Instances of absence (S)

Total days absent (D)

Results

Bradford Factor
Impact level
Review period
Instances (S)
Days absent (D)

The Bradford Factor Calculator computes the Bradford Factor from instances of absence (S) and total days absent (D) within a chosen review period. It helps HR and managers highlight frequent short-term absences that can disrupt scheduling more than occasional long absences.

Introduction

Select a review period (options: 52 weeks, 12 months, 6 months, Quarter) and enter Instances of absence (S) and Total days absent (D). Most organizations use a rolling 52-week window. The canonical formula is:

Impact level labels are indicative; exact thresholds vary by employer.

How to Use the Bradford Factor Calculator

Follow these steps to enter your data and interpret the score.

Choose the Review period (52 weeks, 12 months, 6 months, or Quarter) to match your policy—this sets which absences are counted.
Enter Instances of absence (S) as the number of separate occasions someone was absent; each discrete episode counts once.
Enter Total days absent (D) as the sum of days (or working days) missed during the same review period.
Click Calculate to compute the score using:
Read the Bradford Factor result—higher scores indicate more frequent absences relative to total days.
Check Impact level to gauge severity (labels are guidance; organizations set their own thresholds).
If needed, adjust S or D to run “what-if” scenarios (e.g., how an additional short absence affects the score).
Use Clear to reset the form and start a new calculation.

Frequently Asked Questions

The Bradford Factor (BF) is an HR metric that weights frequent, short-term absences more heavily than occasional long absences over a review period (commonly a rolling 52 weeks). It is used as an internal trigger for review, not a legal threshold.
Use the formula BF = S² × D, where S is the number of absence instances (spells) in the review period and D is the total number of working days absent in that period.
One continuous spell of sickness that begins and ends with a return to work. Multiple consecutive sick days count as one instance. If policy allows half-days, treat each spell consistently per policy.
Count scheduled working days lost. Calendar days should not be used unless your policy explicitly defines absence that way.
Many organizations use a rolling 52-week window. Others use fixed periods (12 months, 6 months, quarter). Choose one and apply it consistently.
Bands vary by employer. A common example is: 0–49 Low, 50–124 Moderate, 125–399 High, ≥400 Very High. Treat these as configurable triggers, not universal standards.
The formula is the same. Count only the employee’s scheduled working days lost. Policies should clarify treatment of variable shifts.
Many policies adjust or exclude certain absences to ensure fairness and compliance with equality guidance. Apply your organization’s policy and document any adjustments.
No. S and D are non-negative. If half-days are allowed, D can be fractional (e.g., 0.5). The score itself is non-negative and typically reported as an integer or one decimal place.
The squaring of S (instances) is designed to emphasize disruption from frequent short absences, which BF treats as more operationally impactful.

Methodology & Sources

Calculator type: HR/operations (attendance management).
Purpose: Provide a standardized Bradford Factor score over a chosen review period to support internal absence-management triggers and conversations.
Modes supported: Rolling 52 weeks, 12 months, 6 months, quarter.

Core formula

(S): number of absence spells in the review period (integer ≥ 0).
(D): total working days (or scheduled shifts) lost in the same period (≥ 0; may be fractional if policy counts half-days).

Worked examples

(Low).
(High).

3. (Low despite a longer single absence).

Interpretation (example bands)

Low: 0–49
Moderate: 50–124
High: 125–399
Very High: ≥400

Note: Bands are illustrative; organizations set their own triggers.

Assumptions

Review window is applied consistently (default: rolling 52 weeks).
Count working days lost (or scheduled shifts), not calendar days.
Each continuous sickness spell counts as one instance.
Policies may exclude or adjust certain absence types (e.g., disability-related); apply locally defined rules.

Input validation & edge cases

Enforce , .
If half-days are allowed, D may be in 0.5 increments; otherwise round to whole working days per policy.
Typically, for whole-day counting; if D < S[/math], prompt for review (e.g., multiple half-day spells).
Undefined/invalid for negative inputs. No division-by-zero risks.
Scores can grow rapidly as S increases; consider capping or flagging outliers for review.

Rounding & display

Report BF as an integer (round half up) or 1 decimal place when fractional D is permitted. Be consistent across periods.

Implementation tips

Store daily/shift-level absence records with timestamps and reasons.
Recompute on a rolling basis to reflect changes immediately.
Log policy exceptions (e.g., excluded absences) for auditability.

Bibliography

South Oxfordshire District Council (2022). Sickness Absence Policy – Bradford Factor (example) — South Oxfordshire District Council (UK Govt – .gov.uk) https://www.southoxon.gov.uk/wp-content/uploads/sites/2/2022/12/Sickness-Absence-Policy-Final-updated-November-2022.pdf
Accessed 2025-10-28
Haswell Parish Council (2024). Attendance Management Policy (Bradford Factor triggers) — Haswell Parish Council (UK Govt – .gov.uk) https://haswellparishcouncil.gov.uk/wp-content/uploads/2024/05/Attendance-Management-Policy-2024.pdf
Accessed 2025-10-28
NHS Scotland (2024). Attendance Policy – Workforce Policies — NHS Scotland (Public sector) https://workforce.nhs.scot/policies/attendance-policy-overview/attendance-policy/
Accessed 2025-10-28