How UK holiday entitlement is calculated

The rules behind the numbers our calculator produces, with the arithmetic written out.

1. The starting point: 5.6 weeks

Almost all workers in the UK have a legal right to 5.6 weeks of paid holiday each leave year. A “week” means a week of your normal working pattern, not five days. So the basic sum is:

days a week x 5.6 = days of paid leave

2. The 28-day cap

The statutory minimum stops at 28 days. Working five days a week already reaches it (5 x 5.6 = 28), so working six days a week does not give 33.6 days by law. Anything above 28 days comes from your contract.

3. Part-time work is already handled

There is no separate part-time rule for a fixed pattern: 5.6 weeks of a three-day week is 16.8 days. If your employer tracks leave in hours, multiply weekly hours by 5.6 instead — 22.5 hours a week gives 126 hours.

4. Starting or leaving mid-year

Starters and leavers are not worked out the same way, which is the single most common mistake — including in a lot of online calculators.

Starting part-way through a leave year

In the first year, leave builds up monthly: one twelfth of the year’s entitlement for each month, counted from the first day of the month you start in, with part days rounded up to the next half day.

full entitlement x (months left in the leave year / 12), rounded up to a half day

Worked example: three days a week, leave year 1 January to 31 December, starting 6 April. Full year = 3 x 5.6 = 16.8 days. April to December is 9 months, so 16.8 x 9 / 12 = 12.6, which rounds up to 13 days. That matches the official GOV.UK calculator for the same inputs. Starting on 30 April gives the same 13 days, because the month you start in counts in full.

Two figures come out of this, and they are not the same thing. The 13 days is your total for the rest of the leave year. What you can actually book on a given date is the part that has built up by then — by 5 July, three monthly instalments have fallen due (6 April, 6 May, 6 June), so 16.8 x 3 / 12 = 4.2 days, rounded up to 4.5 days.

Leaving part-way through a leave year

Leavers are worked out by days employed, not whole months, and the same applies to anyone who both starts and leaves inside one leave year.

full entitlement x (days employed in the leave year / days in the leave year)

Worked example: three days a week, leave year 1 January to 31 December, last day 15 June. That is 166 days of 365, so 16.8 x 166 / 365 = 7.64, rounded up to 7.7 days — again matching GOV.UK. Leave already taken comes off that figure; anything left is normally paid out in the final wage.

Entitlement can always be rounded up and never down, and a contract can be more generous than the legal minimum.

5. Irregular hours: the 12.07% rule

This rule is only for irregular hours and part-year workers, and only in England, Scotland and Wales. It does not apply to everyone: someone on fixed weekly hours still gets 5.6 weeks worked out as days, as in sections 1 to 4 above. Northern Ireland did not adopt the method.

For leave years beginning on or after 1 April 2024, those workers build up leave as hours: 12.07% of the hours worked in each pay period, rounded at the end of each pay period — down below 30 minutes, up at 30 minutes or more. The figure comes from 5.6 holiday weeks divided by 46.4 working weeks. Example: 148 hours gives 17.8636 hours, which becomes 18 hours. There is a dedicated calculator for this.

6. Bank holidays

There is no automatic legal right to paid time off on bank holidays. Employers may count bank holidays inside the 5.6 weeks, which is why “20 days plus bank holidays” is such a common contract. England and Wales have eight bank holidays, Scotland nine and Northern Ireland ten, so “plus bank holidays” is worth more in some places than others — but the 5.6-week legal minimum is the same across the UK either way. Part-time staff should get a pro rata share of any bank holiday allowance, whichever days they happen to work.

Frequently asked questions

Is 20 days plus bank holidays legal?: For a five-day week, yes: 20 days plus 8 bank holidays is 28 days, which meets the minimum. If you work five days a week and get 20 days with bank holidays counted inside them, that is below the minimum.
Why does my employer’s figure differ from this one?: Common reasons: for a new starter they work the first month out in proportion to the days worked rather than giving the whole month (GOV.UK allows either), they round differently, your contract gives more than the statutory minimum, or bank holidays are treated differently. Our result shows each step so you can see where the gap is.
Can unused holiday be paid instead of taken?: Statutory leave can only be paid in lieu when you leave the job. Untaken statutory leave you have built up must be paid in your final pay.
Does the calculator save my answers?: No. What you type is calculated in your browser and is not sent anywhere or stored. The hosting provider still logs the page request itself, as every website does — the privacy page explains the difference.
My result looks wrong. What should I check?: Check the leave year start date, whether your contract gives more than 5.6 weeks, and whether you entered days rather than hours. Half days should be entered as 0.5.

Sources

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