The squaring is the whole mechanism
B = S² × D. S is the number of separate spells, D is the total days. Squaring the spells means the score is driven almost entirely by how often somebody goes off, and barely at all by how long they are off for.
Ten days lost, split four ways:
- One spell of ten days: 10
- Two spells of five: 40
- Five spells of two: 250
- Ten single days: 1,000
A hundredfold range for identical days lost. Nobody in that list took more time off than anybody else.
That is deliberate. The formula was built to surface disruptive short absence, and it does exactly that. But a number this violent should not be acted on by somebody who has not seen the curve, which is why the tool draws it rather than describing it.
The pattern it punishes hardest is the pattern a disability produces
Frequent, short, unpredictable absence is what a great many long term conditions actually look like. A person managing a fluctuating condition takes single days, often, at no notice.
So the Bradford Factor puts disabled employees at the top of the list by design. Not through bias in how it is applied, but through the arithmetic itself.
Acas is explicit about what follows. Where absence may be disability-related, the employer has to consider reasonable adjustments, and the trigger points themselves can be one of them. Raising the threshold, or discounting disability-related absence from the score, is exactly the kind of adjustment the Equality Act 2010 requires where it is reasonable.
The tool shows both figures, with and without. It does not pick one, because that decision belongs to the employer and it needs making deliberately rather than by default.
Pregnancy is not a judgement call
Different rule, and a harder one. Acas says pregnancy-related absence should be recorded separately and not counted towards any trigger point.
So this tool takes those days out before it calculates, rather than including them and warning about it afterwards. Counting pregnancy-related sickness towards an absence trigger is unfavourable treatment because of pregnancy: no qualifying period, no cap on compensation, and very little to argue about.
No trigger point here is law
51, 201, 401, 601. Those numbers appear in employer policies everywhere, and there is nothing statutory about any of them. They are one organisation copying another, and an employer can set whatever figure it likes.
Which also means the figure it sets is not what decides whether acting on it is lawful. Acas is clear that managers should show sensitivity and treat each case on its merits even where a pre-agreed trigger has been passed. A score is a prompt to look, not a decision.
And it does not measure lost time
Worth keeping in view, because it is easy to forget what the number is not saying. Somebody scoring 1,000 has lost ten days. Somebody scoring 25 might have lost twenty five.
The tool shows lost time as a percentage next to the score for exactly that reason. If the actual concern is time lost rather than disruption, the Bradford Factor is answering a different question from the one being asked.
It cannot tell you an absence is disability-related
It works the score and shows what drives it. It does not decide whether an absence is disability-related, which is a question about the Equality Act definition rather than about arithmetic, and it does not tell anybody whether to act. For statutory sick pay there is the sick pay calculator, which was rewritten for the rules that changed in April 2026.
Common questions
How is the Bradford Factor calculated?
B = S² × D. S is the number of separate spells of absence and D is the total days lost, normally over a rolling 52 weeks. Squaring the spells is what makes it work the way it does.
Why does the same number of days give such different scores?
Because the squaring makes frequency almost the only thing that matters. Ten days lost scores 10 as a single absence, 250 as five two day absences, and 1,000 as ten single days. That is a hundredfold range for identical time off, and it is the whole design rather than a quirk.
What is a bad Bradford Factor score?
There is no legal answer, because no threshold is statutory. Employers commonly publish something like 51, 201, 401 and 601, but those are one organisation copying another rather than a standard. An employer can set any number, and the number it sets is not what decides whether acting on it is lawful.
Is the Bradford Factor discriminatory?
The calculation is not, but applying it mechanically can be. Frequent, short, unpredictable absence is exactly what many long term conditions produce, so the formula puts disabled employees at the top by design. Acas is explicit that trigger points themselves can be a reasonable adjustment: raising them, or discounting disability-related absence, is the kind of adjustment the Equality Act 2010 requires where it is reasonable.
Does pregnancy-related absence count towards the score?
No. Acas says pregnancy-related absence should be recorded separately and not counted towards any trigger point. This tool takes those days out before it calculates rather than warning about them afterwards, because it is not a judgement to be weighed up. Counting it is unfavourable treatment because of pregnancy, which needs no qualifying period and carries no cap on compensation.
Can I be dismissed for a high Bradford Factor?
A score is not a reason for dismissal. It is a prompt to look at somebody's absence, and Acas says managers should treat each case on its merits even where a pre-agreed trigger has been passed. A dismissal defended on the arithmetic alone, with no consideration of why the absences happened, is a weak one.