Bradford Factor Calculator: Formula, Worked Scores and Trigger Points

> TL;DR: The Bradford Factor scores absence as S² × D, where S is the number of separate spells and D the total days lost over a rolling 52 weeks. Ten one-day absences score 1,000; one ten-day absence scores 10. Below you’ll find a worked table, a four-column spreadsheet calculator you can copy, common trigger points, how to handle part-timers, and why day-one Statutory Sick Pay since April 2026 makes the score worth watching again.

Two people on your team were off sick for ten days over the last twelve months. One had a single operation and came back on the date the surgeon gave. The other called in on ten separate mornings, mostly Saturdays, and each call cost you a reshuffled rota and a shift run one person short.

On a payroll report those two look identical. The Bradford Factor exists to show the difference.

What is the Bradford Factor?

It’s an absence index that came out of research at the Bradford University School of Management in the 1980s. The premise is blunt: frequent short absences disrupt a business far more than occasional long ones, so they should weigh more in the numbers.

Anyone who has run a shift-based team knows this already. A planned hospital stay gets handled once; you move a few shifts, brief the team, done. A surprise absence at 7:15 on a Saturday gets handled under pressure, usually by phoning around, paying someone overtime or running the floor short. Same number of days. Very different week.

The UK figures explain why HR teams keep coming back to it. According to the Office for National Statistics (release of 1 May 2026), the sickness absence rate in 2025 was 2.0% of working hours, with an estimated 148.8 million working days lost, or 4.4 days per worker. The ONS also flags part-time workers among the groups with the highest absence rates, which matters for the part-time section further down.

How do you calculate a Bradford Factor score?

The formula is B = S² × D, where S is the number of separate absence spells and D the total number of days absent over the same reference period. That period is usually a rolling 52 weeks.

Squaring S is the whole point. It makes the score climb steeply as soon as absences start to repeat, even if each one is short. Here is what that does to four employees who all lost exactly ten days in a year:

Same ten days. A hundredfold gap between the first and last row.

Take a 40-cover gastropub in Leeds with 19 staff across kitchen and floor. A line cook takes six single days off sick over the year: S = 6, D = 6, so 36 × 6 = 216. The head chef has one 18-day absence after knee surgery: S = 1, D = 18, score 18. The head chef cost more in raw days. The line cook cost six emergency rota rebuilds, and in our experience at Shyfter, that’s exactly the moment managers have their “oh” moment: the person they would have named as “always off” is rarely the one causing the most disruption. Sometimes it’s the reverse.

Build your own Bradford Factor calculator in a spreadsheet

You don’t need a dedicated tool to start. Four columns in Excel or Google Sheets and three formulas give you a working Bradford Factor calculator for the whole team.

Sheet 1, the absence log. One row per absence spell, never one row per day.

If your team works weekends or rotating patterns, NETWORKDAYS will undercount. Replace column E with the number of scheduled shifts actually missed, typed in by hand or exported from your rota. That figure is the honest D anyway.

Sheet 2, the score. One row per employee, name in column A, and one formula per column.

The `TODAY()-364` part keeps the window rolling, so an absence from fourteen months ago drops off on its own. Paste the three formulas down the column and you have a live score for every employee.

Three rules decide whether the numbers mean anything. Count only unplanned absence: sickness and unauthorised absence go in, while annual leave, parental leave, training and pre-booked medical appointments stay out. Count one continuous absence as one spell, even if it’s covered by two consecutive fit notes. And keep the same reference period from one year to the next, otherwise your comparisons are worthless.

One thing people often miss on the UK side: pregnancy-related sickness must be logged separately and kept out of the score entirely. More on that below.

What are typical Bradford Factor trigger points?

There is no official scale. Not in UK law, not in any government guidance, not anywhere binding. Each employer sets its own, usually in the absence policy, and the bands below are simply the ones you see most often in UK policies. Treat them as a starting point.

Before you copy that into a policy, run your own team through the calculator and look at the distribution. A contract cleaning firm in Antwerp with 70 people spread over 14 client sites, split shifts and early starts will have a much higher median than a six-person pharmacy. If your first trigger catches a third of the workforce in January, it’s not a trigger. It’s noise.

The other mistake we see most: the manager who walks into the review with the score printed out like a charge sheet. A high score tells you a conversation is needed. It doesn’t tell you why, and the why is the only part you can actually fix.

How do you calculate the Bradford Factor for part-time workers?

The formula doesn’t change, but the input does. Count D in scheduled working days or shifts missed, not calendar days. Someone who works Monday, Wednesday and Friday and is off sick from Monday to Friday has lost three working days, not five.

That gives part-timers a slightly lower D for the same pattern of illness, while S stays the same. Some employers go one step further and convert everything to hours, then divide by a standard shift length. Either approach works if it’s applied the same way to everyone. What you can’t do is set a lower trigger for part-time staff: the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000 rule out treating them less favourably than comparable full-timers.

What UK law says about using the score

The Bradford Factor itself is perfectly legal to use. It’s what you do with it that can go wrong, and three parts of the Equality Act 2010 come up again and again.

• Section 15, discrimination arising from disability. Absences caused by a disability can push someone over a trigger. Acting on that score without adjusting for it needs to be justified, and often can’t be.
• Section 20, reasonable adjustments. Raising the trigger point, or discounting disability-related absences, is a typical adjustment employers are expected to consider.
• Section 18, pregnancy and maternity. Pregnancy-related sickness during the protected period can’t count against an employee. Leave it out of the calculation entirely.

Health data is also special category data under UK GDPR. You need dates and durations to calculate the score. You don’t need diagnoses on the same sheet, and keeping them off it saves you a lot of trouble if someone ever submits a subject access request.

Why the 2026 sick pay reform puts short absences back on the radar

Until April 2026, a one-day absence never cost an employer Statutory Sick Pay. SSP only kicked in after a period of incapacity of four days in a row, and the first three were unpaid waiting days. Short, frequent absences were disruptive but statutorily free.

That has changed. Since 6 April 2026, according to HMRC guidance on GOV.UK, SSP is payable from the first full day of sickness absence, to all eligible employees regardless of earnings, at £123.25 a week or 80% of average weekly earnings, whichever is lower. The Lower Earnings Limit no longer screens anyone out.

Run that through the Leeds line cook. On £480 a week over five qualifying days, 80% of earnings is £384, so the flat rate of £123.25 applies: £24.65 per day. Six single-day absences now cost £147.90 in SSP alone, before the overtime paid to whoever covered. Not ruinous on its own. Multiply it across a team of 19, though, add the cover, and the same pattern that used to cost only goodwill now shows up in payroll every month.

So yes, the old index is relevant again.

From spreadsheet to schedule: what we see in practice

A Bradford score calculated once a year in a spreadsheet is an HR exercise. Calculated continuously from real attendance data, it becomes a scheduling tool.

The spreadsheet above works until the absence log falls behind, which in a busy restaurant or store happens around week three. When absences are recorded directly in the leave and absence management module, every entry already carries a start date, an end date and a type, which is exactly what S and D need, with no re-keying. The reports then break the result down by team, site or contract type. When three people in the same store sit above 300 while the rest of the network hovers around 40, it’s almost never about those three people. Look at the rota they’re on.

Cross-check the score with your other numbers too. A rising Bradford average in one team often comes a few months before a wave of resignations, and it pairs well with the wider indicators in our guide to understanding and reducing employee absenteeism. For absences that come with no warning at all, a clear no call no show policy does more than any score.

One last word on gaming the system. Once staff know a Bradford score exists, some will stretch a one-day absence into three to keep S down. That’s a known side effect, and the cure isn’t a cleverer formula; it’s using the score to open conversations rather than close them.

Want to see your own team’s Bradford scores without rebuilding the spreadsheet every month? Book a free demo of Shyfter and we’ll run the calculation on one of your sites with you.

Frequently asked questions

Is the Bradford Factor legal to use in the UK?

Yes, it’s an internal management tool and no law bans it. The risk lies in how it’s applied: disability-related absences may need to be discounted or given a higher trigger under the Equality Act 2010, and pregnancy-related sickness must be left out entirely. Use the score to start a conversation, never as the sole reason for a sanction.

What is a bad Bradford Factor score?

There’s no official threshold. Many UK employers start an informal conversation at around 51 and a formal review at around 125, with further stages at 400 and 650. The right bands depend on your sector, so check the real distribution of scores in your team before you fix them in a policy.

Should holidays count in the Bradford Factor?

No. Only unplanned absence counts, which in practice means sickness and unauthorised absence. Annual leave, parental leave, training days and pre-booked appointments are planned and don’t disrupt the rota. Including them would push up the scores of your most reliable people.

How long does a Bradford Factor score last?

Most employers use a rolling 52-week window, so each absence drops out of the score one year after it started. Some use a rolling six months to react faster, but scores then swing a lot from month to month. Whatever you choose, write it into the absence policy and keep it the same every year.