Bradford factor calculator

The Bradford factor is an absence score that weights frequent short absences more heavily than one long one. Enter the number of separate absences someone had in the period and the total days they lost, and you get their score, the average length of each absence and what the same days would score as one absence.

Bradford factor score

Separate absences in the periodCount each unbroken absence once, however many days it lastedTotal days absentWorking days the person was due to work

Bradford factor score96

Average days per absence1.5

Score if it had been one absence6

A score starts a conversation. It isn't evidence of anything on its own.

It's an HR convention, not a legal requirement, and a score proves nothing on its own. What matters is which absences you leave out before counting, and what you do with the number.

Check the reasons before you score. In Great Britain, absence linked to pregnancy or a disability needs different handling under the Equality Act 2010. See "Absences to leave out" below.

How the Bradford factor works

Count the separate absences in the period, called spells (S), and the total working days lost (D). Multiply the number of spells by itself, then by the days:

Bradford factor = S × S × D

An absence from a Thursday to the following Tuesday is one spell of four working days, not two spells. The period is usually a rolling 52 weeks, so each absence drops out a year after it happened.

Because S is squared, the score climbs far faster with the number of absences than with their length. The same 12 days, lost four different ways:

Pattern	S	D	Score
One absence of 12 days	1	12	12
Three absences of 4 days	3	12	108
Six absences of 2 days	6	12	432
Twelve single days	12	12	1,728

The thinking is that short, unplanned absences are harder to cover than one longer absence that can be planned around. That weighting is also the method's weak spot.

Worked example

A fictional 60-person contact centre looks back over a rolling 52 weeks. Two advisers have each lost 6 working days.

Adviser A had one absence of 6 days with flu: 1 × 1 × 6 = 6.
Adviser B had four absences, of 1, 2, 1 and 2 days: 4 × 4 × 6 = 96. These are the calculator's starting figures.

B's score passes the review point in the company's absence policy, so the team leader books an absence review. HR checks the reasons first. Both 2-day absences were hospital tests for a long-term condition B told HR about last year. HR asks whether the condition could be a disability and, in line with Acas guidance, leaves those days out. On the two remaining one-day absences, B's score is 2 × 2 × 2 = 8.

The review becomes a support conversation: an occupational health referral and shifts planned around future appointments, noted on the return to work form.

How to read the score

There's no official scale. Acas says there are no legal rules on how or when absence should be reviewed, and that review points shouldn't automatically lead to disciplinary action. A score is useful because:

it shows a pattern that a total of days lost hides, as with Adviser B;
it applies your policy evenly, as long as the policy says which score starts a review and what a review involves;
it opens a conversation about how the person is and what would help. A one-to-one is often a better start than a formal meeting.

Track each person's score over time; don't rank people against each other.

Absences to leave out or treat differently

Pregnancy-related sickness. Under section 18 of the Equality Act 2010, treating a woman unfavourably because of illness caused by her pregnancy during the protected period is discrimination. Acas says to record it separately and not count it towards review points.
Disability-related absence. Under section 15, if an employer knows or should know about a disability, treating the person unfavourably because of something arising from it, such as absence, is discrimination unless it's a proportionate way of achieving a legitimate aim. Employers must also make reasonable adjustments, and Acas gives not counting some or all of the absence, or raising the review point, as examples.
Time off for dependants. Emergency time off to deal with a dependant isn't sickness, and GOV.UK says employers must not treat employees unfairly for taking it.
Absence caused by work, such as an injury on site, which Acas lists among the things to check at a review.

These rules apply in Great Britain; Northern Ireland has its own equality law. In the US, the Family and Medical Leave Act regulations say FMLA leave can't be counted under "no fault" attendance policies. This summarises official guidance, not legal advice.

Common mistakes

Treating a score as an automatic warning. Acas warns that people who see the system as punishment may come back while still unwell to avoid a review.
Scoring before checking the reasons, so protected absences push the number up.
Mixing calendar days and working days. For part-timers, count only the days they were due to work.
Overlooking long-term absence. One 40-day absence scores just 40, yet that person may need more support than anyone with a high score.
Sharing a league table. The ICO says employers must not publish individual workers' sickness absences where everyone can see them.

Frequently asked questions

What is a good Bradford factor score?

There isn't one. No law or official body sets a scale, so each employer using the method picks its own review points and writes them into its absence policy. A lower score just means fewer, shorter absences.

Is the Bradford factor legal in the UK?

Using it isn't against the law: Acas says there are no legal rules on how absence is reviewed. Using it carelessly can be. Scoring pregnancy-related sickness, or disability-related absence without considering adjustments, can lead to discrimination claims.

How do I count half days?

Add it to D as 0.5 and count it as one spell in S. Whatever rule you pick, apply it to everyone and put it in the policy.