United Kingdom. Working Time Regulations 1998 limits applied
Shift pattern generator: build the cycle, then test it against the law
Rota software optimises for cover, not compliance, and can break the Working Time Regulations. From days on, days off and shift length, get cycle length, average week, round-the-clock crews, and whether the 48 hour average and 11 hour rest hold.
48 hours
the average weekly working limit, normally averaged over 17 weeks
11 hours
rest between working days, which a 12 hour shift leaves exactly 12 hours for and a 14 hour shift does not
8 hours
the average night workers must not exceed in a 24 hour period, and a hard ceiling where the work involves special hazards or heavy strain
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What this is based on
- The 48 hour average weekly limit follows gov.uk: "you cannot work more than 48 hours a week on average, normally averaged over 17 weeks". A worker may opt out in writing. Excluded: jobs requiring 24 hour staffing, armed forces, emergency services, and roles where working time is not measured and the worker controls their own decisions (gov.uk).
- Average weekly hours come from the cycle's SHAPE, not a calendar: days on over cycle length, times seven, times the shift length. That is exact for a repeating cycle. It is why 4 on 4 off at 12 hours gives 42 hours a week, not the 48 people assume.
- Daily rest is 11 hours between working days and the weekly rest is either an uninterrupted 24 hours each week or an uninterrupted 48 hours each fortnight. Workers also have the right to one uninterrupted 20 minute rest break during the working day where they work more than 6 hours (gov.uk).
- The daily rest figure assumes consecutive shifts start at the same clock time, so the gap is 24 hours minus the shift. A pattern rotating forward from nights to days inside a cycle can give a shorter gap. Check that transition by hand.
- Night workers regularly work at least 3 hours between 11pm and 6am, unless another period is agreed. They must average no more than 8 hours in 24, usually over 17 weeks, or up to 52 by agreement. With special hazards or heavy physical or mental strain, they "cannot work longer than 8 hours in any 24-hour period" (gov.uk).
- The crew count is arithmetic, not a rota: shifts needed a day multiplied by the cycle length over the days on. It tells you how many crews the pattern implies for the cover you asked for. It does not account for holiday, sickness, training or the relief factor, all of which push the real headcount above it.
- Under 18s are not modelled. Guidance on gov.uk says they "cannot work more than 8 hours a day or 40 hours a week". 16 and 17 year olds "cannot work between midnight and 4am", and usually not 10pm to 6am, with narrow industry exceptions. Check any pattern with young workers against those rules directly.
- No figure here is a market rate, a typical pay rate or a benchmark. Everything the tool returns is derived from the pattern you enter and the published statutory limits, and nothing is estimated.
Shift Pattern Generator is an information site. It is not affiliated with, endorsed by or connected to gov.uk, Acas, the Health and Safety Executive or any government body, and it is not a law firm or an employment adviser. Nothing here is legal advice on a particular rota. The tool applies published statutory limits to the pattern you enter and reports where it sits against them; whether a specific pattern is lawful also depends on individual opt-outs, exempt categories, collective or workforce agreements and the sector rules for drivers, seafarers and young workers, none of which it models. We publish no figure that is not either derived from your own inputs or taken from a source cited on this page.
Common UK shift patterns: cycle, average week and Working Time Regulations position, 2026
Last updated
The average week a shift pattern produces is rarely the number people carry in their heads, and it is the number the 48 hour limit is measured against. This table works the arithmetic for the patterns most often used in UK manufacturing, care, security and logistics.
Average weekly hours are days on divided by cycle length, times seven, times the shift length. That is exact for any repeating cycle. Crews are shifts needed a day for continuous 24 hour cover multiplied by cycle length over days on, rounded up to a whole crew, and they exclude any relief factor for holiday, sickness and training. The Working Time position column applies three published limits and no interpretation: the 48 hour average week normally averaged over 17 weeks, the 11 hour daily rest between working days, and the 8 hour average in a 24 hour period for night workers. Where a pattern is over a limit the table says which limit and by how much, rather than saying the pattern is unlawful, because an individual opt-out, an exempt category or a collective or workforce agreement modifying the reference period can each make an over-limit pattern lawful. Every figure is reproducible from the two inputs in the first column and the calculator above runs the same arithmetic, so the tool and the table cannot disagree.
| Pattern | Cycle | Average week | Crews for 24 hour cover | Working Time position on these figures |
|---|---|---|---|---|
| 4 on 4 off, 12 hour shifts | 8 days | 42 hours | 4 | Inside the 48 hour average. Night average is 6 hours in 24, inside the night limit. 12 hour gap clears the 11 hour daily rest by an hour. |
| 3 on 3 off, 12 hour shifts | 6 days | 42 hours | 4 | Identical average to 4 on 4 off, because the ratio is the same. The shorter cycle rotates through the calendar week faster, which changes weekend incidence, not compliance. |
| 5 on 2 off, 8 hour shifts | 7 days | 40 hours | 5 | Inside every limit. Needs five crews for continuous cover because 8 hour shifts mean three shifts a day. |
| 6 on 4 off, 12 hour shifts | 10 days | 50.4 hours | 4 | Over the 48 hour average by 2.4 hours a week. Lawful only with individual opt-outs, an exempt category, or a longer reference period agreed under a collective or workforce agreement. |
| 7 on 7 off, 12 hour shifts | 14 days | 42 hours | 4 | Inside the 48 hour average. The seven consecutive nights need checking against the weekly rest rule: 24 uninterrupted hours a week, or 48 uninterrupted hours a fortnight. |
| 2 on 2 off 3 on, 12 hour shifts | 14 days | 42 hours | 4 | Inside the 48 hour average. Cycle is a fortnight, so it fixes the weekend rotation the shorter cycles keep moving. |
| 4 on 4 off, 12 hour shifts, hazardous night work | 8 days | 42 hours | 4 | Inside the 48 hour average but 4 hours over the absolute 8 hour ceiling that applies where night work involves special hazards or heavy physical or mental strain. That ceiling does not average out. |
- A 4 on 4 off pattern on 12 hour shifts averages 42 hours a week, not 48: the cycle works 4 days in every 8, which is 3.5 shifts a week.
- A 6 on 4 off pattern on 12 hour shifts averages 50.4 hours a week, which is over the 48 hour average limit before any overtime is added.
- Continuous 24 hour cover on 12 hour shifts needs four crews on any 1:1 on-off ratio, and five crews on 8 hour shifts with a 5 on 2 off pattern.
- The 11 hour daily rest right means a shift longer than 13 hours cannot be worked on consecutive days at the same start time without breaching it.
- Night workers must not work more than an average of 8 hours in a 24 hour period, but where the work involves special hazards or heavy physical or mental strain the 8 hours is an absolute ceiling with no averaging.
- The 48 hour week is an average normally taken over 17 weeks, so a pattern can exceed 48 hours in a given week and still comply.
Cite this page
“Common UK shift patterns: cycle, average week and Working Time Regulations position, 2026”, Shift Pattern Generator, https://shiftpatterngenerator.co.uk/ (updated 2026-08-15). Average weekly hours are days on divided by cycle length, times seven, times the shift length. That is exact for any repeating cycle. Crews are shifts needed a day for continuous 24 hour cover multiplied by cycle length over days on, rounded up to a whole crew, and they exclude any relief factor for holiday, sickness and training. The Working Time position column applies three published limits and no interpretation: the 48 hour average week normally averaged over 17 weeks, the 11 hour daily rest between working days, and the 8 hour average in a 24 hour period for night workers. Where a pattern is over a limit the table says which limit and by how much, rather than saying the pattern is unlawful, because an individual opt-out, an exempt category or a collective or workforce agreement modifying the reference period can each make an over-limit pattern lawful. Every figure is reproducible from the two inputs in the first column and the calculator above runs the same arithmetic, so the tool and the table cannot disagree.
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Related guides
Each one cites where its numbers come from.
Common questions
How many hours a week is a 4 on 4 off shift pattern?
42 hours a week on 12 hour shifts, six under the 48 hour limit people expect. It works 4 days in 8, half the days: 0.5 times 7 times 12. 3 on 3 off and 7 on 7 off also average 42 on 12 hour shifts, as all work half the days.
How many crews does a 24 hour operation need?
Four on 12 hour shifts with any equal on-off ratio; five on 5 on 2 off at 8 hours. Take shifts needed a day (cover hours over shift length) times cycle length over days on. That minimum has no relief factor: holiday, sickness, training and turnover push real headcount higher. Operations typically staff a continuous rota above the bare four.
Is a 6 on 4 off shift pattern legal in the UK?
On 12 hour shifts it averages 50.4 hours a week, over the 48 hour average limit. Not automatically unlawful, but something must carry it: individual written opt-outs, an exempt category like 24 hour staffing, or a longer reference period under a collective or workforce agreement. Without one, it breaches the limit on its own arithmetic.
How much rest is required between shifts in the UK?
11 uninterrupted hours between working days. Consecutive shifts at the same start time leave 24 hours minus the shift: 12 hour shifts leave 12 and comply, 14 hour shifts leave 10 and do not. Breaches mostly come in a forward rotation, a late finish then an early start: both look normal, yet the gap is under 11 hours.
What are the limits on night shifts in the UK?
Night workers regularly work at least 3 hours between 11pm and 6am, unless another period is agreed. They must average no more than 8 hours in 24, usually over 17 weeks, or up to 52 by agreement. With special hazards or heavy physical or mental strain, 8 hours in any 24 is an absolute ceiling, with no averaging.
Does the 48 hour limit apply to every week?
No. It is an average, normally over 17 weeks, so one week above 48 hours is no breach if the reference-period average stays inside. That is why seasonal operations can lawfully run heavy peaks. An employer relying on averaging must measure it: assuming the shoulder weeks bring it down is not knowing they did.
Can I use this as a rota generator or a shift pattern planner?
Use it as the first step of one. Enter days on, days off, shift length and hours to cover. It returns cycle length, the average week against the 48 hour limit, crews needed and rest gaps. Once a pattern passes, rota software or a spreadsheet puts names on days; check its output against these numbers.
Does a shift pattern change how much annual leave staff get?
It changes how the entitlement is expressed, not its size. Statutory leave is 5.6 weeks a year; for shift workers a week means their normal hours. So 12 hour patterns usually track leave in hours, not days. 5.6 weeks of a 42 hour average converted to days at 8 hours misleads; at the real shift length it does not.
Sources
This site's own datasets, every figure quoted from its source and dated:
- The Shift Premium Rates carries 2 published figures read from 2 sources' own pages, under different breakdowns, so no one range is stated, read 11 November 2026.
- The median published figure in the Shift Work Prevalence is 22.50 percent across 2 sources' own pages (range 19 to 26 percent), read 12 October 2026.
- The Working Time Rules carries 6 published figures read from 4 sources' own pages; the 4 published figures given without a breakdown run from 10 to 48 hour, read 7 November 2026.
Test a pattern before you consult on it
Three numbers in, and you have the cycle, the average week, the crews and the Working Time position.
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