Bradford Factor Calculator NZ 2026/27
This calculator scores staff absence using the Bradford Factor, an index designed to distinguish between an employee who was off for two weeks with one illness and an employee who took ten separate single days across the year. The formula treats those two cases very differently on purpose: the number of separate spells is squared and then multiplied by the total days, so frequency dominates duration. The reasoning is that unpredictable short absences are more disruptive to a workplace than a single longer one, because they cannot be planned around. You can score one employee or a whole team of up to six in the same table, and the calculator ranks them, flags the highest, and shows which trigger band each falls into. There is also a comparison view showing the same total days absent spread across different numbers of spells, which is the fastest way to understand what the index actually rewards and punishes. One important caution runs through this page: the trigger points in common use come from organisational practice rather than from New Zealand law, and a Bradford score tells you nothing about why someone was absent. In New Zealand an employer must still act as a fair and reasonable employer, which means a proper process and genuine consideration of the circumstances. This is a management screening tool, not employment advice.
Review period: a rolling 12 months is the most common. The period is your choice, but it must be identical across employees for scores to be comparable.
Trigger bands shown (51, 201, 401) are the thresholds most commonly seen in published attendance policies, originating largely in United Kingdom public sector practice. They are set by the employer, not by law. They have no statutory basis in New Zealand and are editable here for that reason.
NZ sick leave entitlement: 10 days paid sick leave a year after 6 months continuous employment, carrying over to a maximum entitlement of 20 days at any one time, under the Holidays Act 2003 as amended. An employee using their entitlement is exercising a legal right.
Commonly excluded from scoring: annual leave, bereavement leave, parental leave, jury service, workplace injury absence, and any absence related to a disability or pregnancy. Including those categories risks a discrimination claim as well as producing a misleading score.
Use working days, not calendar days, so a Friday to Monday absence counts as 2 days.
This is not employment law advice. Take advice before acting on any absence score.
Last verified: July 2026.
Team scores
| Employee | Spells | Days | Calculation | Score | Band |
|---|
Ranked highest to lowest. The highest score is highlighted, which is a prompt to look at that person's circumstances rather than a conclusion about them.
Why the same days give very different scores
| Pattern | Spells | Days | Score | Band |
|---|
Every row above involves exactly the same number of days away from work. Only the pattern differs, and the score varies enormously. That is the index working as designed, and also the reason it should never be applied without understanding the cause.
Your trigger bands
| Below 51 | No action indicated | |||
| 51 and above | Informal conversation | |||
| 201 and above | Written review | |||
| 401 and above | Formal process | |||
Employer policy, not New Zealand law. Whatever thresholds you set must be written down, communicated, and applied to everyone the same way.
What The Formula Does And Why It Squares The Spells
The Bradford Factor is deliberately lopsided. It multiplies the total days absent by the square of the number of separate absences, which means frequency matters enormously and duration barely registers.
The reasoning comes from the disruption a workplace actually experiences. One person off for two weeks with a broken ankle is a known quantity: the work gets reallocated, cover is arranged, and everyone plans around it. The same fourteen days taken as fourteen unconnected single days is a different problem entirely, because each one arrives without warning, each one leaves a shift short at short notice, and no planning is possible.
The index was developed at the Bradford University School of Management in the 1980s and became widely used in the United Kingdom, particularly in the public sector, before spreading to employers elsewhere including New Zealand.
Worked Example: 4 Spells And 8 Days Scores 128
Take the first employee in the default table. Over the review period they were absent on four separate occasions, totalling eight working days.
The calculation is spells squared, so 4 × 4 = 16, multiplied by the 8 total days, giving 128.
Compare that with the second employee, who was absent for twelve days in a single continuous spell. Their score is 1 × 1 × 12, which is just 12. They were away half as long again, and score barely a tenth as much.
The third employee had seven spells totalling nine days, scoring 7 × 7 × 9 = 441, which is the highest in the team despite being away for only one day more than the first employee.
That spread, from 12 to 441 across three people whose total absence ranges from 8 to 12 days, is the index doing exactly what it was designed to do.
The Comparison Table Is The Clearest Way To Understand It
Hold the total days constant at ten and vary only the pattern.
One spell of ten days scores 1 × 1 × 10 = 10. Two spells of five days score 2 × 2 × 10 = 40. Five spells of two days score 5 × 5 × 10 = 250. Ten separate single days score 10 × 10 × 10 = 1,000.
Same person, same ten days away from work, scores ranging from 10 to 1,000. Under the commonly used trigger points, the first case indicates no action at all and the last would sit well beyond a formal process threshold.
Whether that is fair depends entirely on why the absences happened, which is the one thing the formula cannot see.
Trigger Points Are Yours, Not The Law's
The figures of 51, 201 and 401 appear so consistently in published attendance policies that they are often assumed to be some kind of standard. They are not. They are conventions that spread through copying, largely from United Kingdom public sector policies, and they carry no legal weight anywhere, least of all in New Zealand.
This matters practically. An employer using this index should choose thresholds that suit the workforce, write them into a policy, tell employees what they are, and then apply them consistently. Thresholds discovered after the fact, or applied to one employee and not another, are considerably worse than having none at all.
It is also worth choosing them with some awareness of what they mean in practice. A trigger of 51 is reached by three spells totalling six days, which for a parent of young children in a New Zealand winter is an entirely ordinary year and well within their statutory sick leave entitlement of 10 days.
Where This Index Gets Employers Into Trouble
The Bradford Factor measures a pattern. It has no idea what caused it, and that gap is where the legal risk sits.
New Zealand employees are entitled to 10 days of paid sick leave a year after six months of continuous employment, accumulating to a maximum entitlement of 20 days. An employee using that entitlement is exercising a legal right, and a high score may simply mean they have been unlucky with a series of unrelated minor illnesses.
More seriously, a high score can be a direct consequence of a disability, a chronic condition, pregnancy, or caring responsibilities. Acting on the score without understanding the cause risks a personal grievance for discrimination as well as for unjustified action. Most employers using the index exclude absence related to disability, pregnancy, workplace injury, bereavement and parental leave for exactly this reason, and those exclusions should be decided in advance rather than case by case.
Even setting law aside, the index creates perverse incentives. An employee who understands the formula learns quickly that returning to work while still unwell avoids a second spell, and that if they are going to be off anyway they may as well stay off longer, since duration is barely penalised. Both behaviours are worse for the employer than the absence being measured. Presenteeism in particular spreads illness through a team and reduces the quality of work being done.
Using It Well
The honest case for the Bradford Factor is narrow but real. In a team large enough that patterns are genuinely hard to see, it surfaces the person whose absence pattern is unusual, which is information a manager might otherwise miss for a year.
Used that way it is a prompt to have a supportive conversation, and those conversations frequently reveal something worth knowing: an undiagnosed health problem, a caring situation the employee had not felt able to raise, a workplace issue causing genuine stress, or occasionally a straightforward attendance problem that needs addressing. All four of those are better found early.
What it cannot do is decide anything. The moment a score is used to trigger an automatic consequence rather than an enquiry, it stops being a management tool and becomes a liability. Absence has a real cost, and it is worth sizing, but the answer to that cost is almost never a formula applied without judgement.
Related NZ Employment and Payroll Calculators
- Sick Leave Calculator: the statutory entitlement, accrual and carry-over rules behind these absences.
- Attrition Rate Calculator: staff turnover as a percentage, the companion measure to absence.
- Employee Cost Calculator: what a day of paid absence actually costs you.
- Annual Leave Calculator: entitlements that should be excluded from any absence score.
- Payroll Cost Calculator: the total employment cost the absence is measured against.