Zero-hours and irregular hours holiday calculator

Work out the holiday a zero-hours, casual or irregular-hours worker has built up. Enter the hours they worked in each pay period. The calculator applies the 12.07% rule, rounds each period the way the law says, and works out rolled-up holiday pay if you pay it that way.

For leave years starting on or after 1 April 2024, in England, Scotland and Wales. Checked against legislation.gov.uk and GOV.UK on 26 October 2026.

An estimate to check your figures. It does not decide whether someone is an irregular-hours worker. Not legal advice.

How holiday builds up for irregular hours

For leave years starting on or after 1 April 2024, irregular-hours and part-year workers in England, Scotland and Wales build up holiday as they work (Working Time Regulations 1998, regulation 15B):

12.07% of the hours worked in each pay period is added on the last day of that period.
Round each period on its own. Part of an hour under 30 minutes counts as nothing. 30 minutes or more counts as a whole hour.
Stop at 28 days of statutory leave in a leave year. The law says 28 days and does not turn that into hours; the calculator counts a day as the usual working day you enter.
Take off what they have used. What is left is theirs to take, from the next pay period on.

Where does 12.07% come from? 5.6 weeks of holiday out of the 46.4 weeks left in a year for working: 5.6 ÷ 46.4 = 0.1207. Our guide to zero-hours holiday explains the background.

Worked examples

Hours in the pay period	12.07%	Holiday built up
30 hours in a week (the GOV.UK example)	3.62 hours (3h 37m)	4 hours: 37 minutes rounds up
17.5 hours in a week	2.11 hours (2h 7m)	2 hours: 7 minutes is dropped
120 hours in a month	14.48 hours (14h 29m)	14 hours: 29 minutes is dropped
125 hours in a month	15.09 hours (15h 5m)	15 hours

Over four weekly pay periods of 30, 12, 0 and 25 hours, the worker builds up 4 + 1 + 0 + 3 = 8 hours. That is the example already filled in above. If they have taken 6 hours of holiday this leave year, 2 hours are left.

Rolled-up holiday pay

For the same workers, you can pay holiday as it is earned instead of when it is taken: a 12.07% uplift on their pay for work done in each pay period (regulation 16A). The rules:

Pay it at the same time as the pay for the work.
Show it on the payslip as its own amount.
Work it out on all the pay that counts towards a week’s pay, not only the basic hourly rate.
It is only for irregular-hours and part-year workers. For regular-hours staff, full or part time, holiday pay cannot be included in the hourly rate.

Example: 30 hours at £12.50 is £375 of pay. 12.07% of £375 is £45.26 of rolled-up holiday pay on that payslip. The worker still takes their holiday hours; that time off is not paid again.

If you do not roll it up, pay holiday when it is taken, at the worker’s average pay over the previous 52 weeks in which they were paid (GOV.UK, holiday pay).

Before 1 April 2024, and other cases

For a leave year that began on or before 31 March 2024, the older rules applied until it ended. GOV.UK’s holiday entitlement calculator estimates those years from average days or hours.
While a worker is off sick or on statutory leave such as maternity leave, holiday still builds up: 12.07% of their average weekly hours over the 52 weeks before, for each week they are off (regulation 15C).
Staff on fixed part-time hours are not irregular-hours workers. Use the pro-rata holiday calculator for them.
From 6 April 2026, employers must keep records of annual leave and holiday pay for 6 years. See our holiday record-keeping guide.

Sources

Working Time Regulations 1998, regulation 15B (12.07%, rounding, 28-day cap) and regulation 16A (rolled-up pay)
GOV.UK: calculate leave entitlement and GOV.UK: holiday pay

Irregular hours in Rotaleave

Tick “Irregular hours or part-year worker” on someone’s settings and their holiday builds up at 12.07% of the hours worked in each pay period, rounded to the nearest hour. The hours come from their approved timesheets, or you type them in. Pay periods can be weekly, fortnightly, four-weekly or monthly. See how allowances work and holiday in hours.

Zero-hours holiday questions

Why does the calculator round each pay period separately?

Because the law does. Holiday accrues on the last day of each pay period, and any part of an hour is rounded there and then: under 30 minutes counts as nothing, 30 minutes or more as a full hour. Adding up the unrounded figures first and rounding once at the end can give a different answer.

Can a zero-hours worker build up more than 28 days in a year?

Not under the 12.07% rule. It stops at 28 days of statutory leave in a leave year, however many hours are worked. You can give more as a contractual extra. Enter their usual working day and the calculator shows the cap in hours.

Who counts as an irregular-hours worker?

Someone whose paid hours in each pay period are, under their contract, wholly or mostly variable. Zero-hours and casual staff usually are. Part-year workers are a separate group: they have weeks in the year when they do not work and are not paid, such as some term-time staff. Both use the 12.07% rule.

If holiday pay is rolled up, does the worker still take time off?

Yes. Rolled-up pay only changes when holiday is paid. The worker still builds up leave and still has the right to take it. Because they have already been paid for it on each payslip, you do not pay them again when they take the days off.

Does the 12.07% rule apply in Northern Ireland?

No. The 2024 rules for irregular-hours and part-year workers are in the Working Time Regulations for England, Scotland and Wales. Northern Ireland has its own working time law, so check nidirect for staff there.

Related tools & guides

Guide: zero-hours holiday

The 12.07% method and the 2024 changes explained.

Term-time only holiday calculator

For school support staff on part-year contracts.

Holiday entitlement calculator

The 5.6 weeks for staff with a fixed pattern.

Bank holiday calculator

A part-timer’s fair share of bank holidays.

Weekly timesheet template (Excel)

Record the hours worked that holiday is built from.

Guide: holiday records

What to keep from April 2026, and for how long.