Annual Leave Calculator UK: Work Out Your Holiday Entitlement

This free annual leave calculator works out your UK statutory holiday entitlement in seconds — whether you work full-time, part-time, irregular hours, or started or left a job partway through the year. Enter your working pattern below and get a straight answer, backed by the actual rules that apply to it.

What Counts as “Annual Leave” Under UK Law

Every worker in the UK — full-time, part-time, on a zero-hours contract, or an agency worker — has a legal right to paid time off work. This right comes from the Working Time Regulations 1998, and it sits separately from any extra holiday your employer chooses to offer on top.

The statutory minimum is 5.6 weeks of paid annual leave a year. For someone working a standard five-day week, that works out to 28 days. It’s worth being precise about what “5.6 weeks” actually means, because it’s the number everything else in this article is built on — pro-rata leave, part-year accrual, and new-starter calculations are all just different ways of applying the same 5.6-week rule to different working patterns.

Your employer is allowed to count bank and public holidays as part of that 5.6-week entitlement, rather than giving them on top. Most UK employers do this, which is why 28 days often includes the 8 bank holidays in England and Wales rather than sitting on top of them — but it isn’t guaranteed, so it’s worth checking your contract.

How to Calculate Annual Leave: The Basic Formula

If you want to calculate annual leave by hand rather than using the tool above, the underlying maths is genuinely simple.

Full-time entitlement

For a worker on a standard five-day week, the statutory calculation is:

Days worked per week × 5.6 = annual leave entitlement in days

5 × 5.6 = 28 days. That’s the number you’ll see quoted almost everywhere as “the UK minimum,” and it’s accurate for anyone working a full five-day week with no unusual pattern.

Part-time and pro-rata entitlement

The same formula applies to part-time staff — this is what “pro-rata annual leave” actually means in practice. You’re not entitled to less protection than a full-time worker; you’re entitled to the same 5.6 weeks, scaled to how many days you actually work.

The same principle works in hours instead of days if your contract is written that way: multiply your normal weekly hours by 5.6. Someone working 20 hours a week, for example, is entitled to 112 hours of paid leave a year (20 × 5.6).

One genuinely common point of confusion: pro-rata leave is based on days worked per week, not hours per day. Someone working three full 8-hour days a week gets the same day-based entitlement as someone working three short 4-hour days — 16.8 days — because the calculation counts working days, not hours in a day. The hours-based method exists as an alternative for irregular schedules, not as a way to get a “more accurate” number for a fixed weekly pattern.

Irregular Hours and Part-Year Workers: The 12.07% Method

If your hours genuinely vary week to week — think zero-hours contracts, casual work, or term-time-only roles — the day-based formula above doesn’t work cleanly, because there’s no fixed “days per week” to multiply. For these workers, UK law uses a different method: leave accrues gradually, based on hours actually worked.

Why the rule changed in 2024

This area has a genuinely messy recent history, and getting it right matters if you’re checking your own entitlement. For years, the accepted approach (from Acas guidance) was to calculate holiday at 12.07% of hours worked. Then the 2022 Supreme Court ruling in Harpur Trust v Brazel found that method unlawful for part-year workers, on the basis that it could pay them less than the 5.6 weeks a similarly-patterned full-year worker would get.

That ruling caused real confusion for employers of term-time and seasonal staff. Parliament responded with new regulations — the Employment Rights (Amendment, Revocation and Transitional Provision) Regulations 2023 — which came into force for leave years starting on or after 1 April 2024 and reinstated the 12.07% accrual method specifically for irregular-hours and part-year workers. If your leave year started before that date, older rules may still apply to the year in question.

Worked example

Under the current rules, Acas guidance sets out the method plainly: irregular-hours and part-year workers accrue holiday at 12.07% of the hours they work in each pay period, calculated on the last day of that pay period. The 12.07% figure itself comes from dividing the 5.6-week statutory entitlement by 46.4 (the 52 weeks in a year minus 5.6 weeks of leave).

So if you work 70 hours in a month, your accrued leave for that month is 70 × 0.1207 = 8.449 hours — rounded, using the official rule, to 8 hours (because the 0.449 fractional part is under 30 minutes). If someone else worked 60 hours in a pay period, 60 × 0.1207 = 7.242 hours, which also rounds down to 7 hours. The rounding rule cuts the other way once the fractional part reaches half an hour or more.

This is exactly the calculation the “Irregular hours” tab of the calculator above runs for you.

Starting or Leaving a Job Partway Through the Leave Year

New starters and leavers are where most manual annual-leave calculations go wrong, because the full-year number needs pro-rating to however much of the leave year you’ve actually worked.

The principle is straightforward: work out what proportion of the leave year you were (or will be) employed for, and apply that same proportion to your full-year entitlement.

For example, if your leave year runs 1 April to 31 March, your full-year entitlement is 28 days, and you started on 1 October — exactly halfway through the year — you’d be entitled to roughly 14 days for that first leave year. Some employers apply this monthly (accruing one-twelfth of your annual entitlement for each complete month worked) rather than daily; both approaches should land close to the same figure, and your employer can round up but not down.

The same logic applies in reverse when you leave a job partway through a leave year: you’re entitled to be paid for any leave you’ve accrued but not taken, calculated the same way. This is a statutory right — it’s why your final payslip usually includes an “outstanding holiday pay” line if you leave with days untaken.

Bank Holidays, Carry-Over, and Sick or Parental Leave

A few extra rules matter once you’re comparing your own entitlement against what your employer is actually giving you:

• Bank holidays can be included within your statutory 5.6 weeks, or given on top, depending on your contract — there is no automatic legal right to bank holidays as extra paid days off above the statutory minimum, unless your contract says so.
• Leave continues to build up while you’re on sick leave, maternity, paternity, parental, shared parental, or adoption leave. You don’t lose annual leave entitlement because you were on one of these types of statutory leave.
• Carry-over is limited by default, but the rules allow workers to carry over leave they couldn’t take due to statutory family leave, and up to 4 weeks can be carried over for up to 18 months where sickness prevented someone taking it, or where an employer failed to give them a genuine opportunity to take it.
• Employers can require you to take leave at specific times (for example, over a Christmas shutdown), as long as they give the correct amount of notice — but they can’t simply prevent you from taking your statutory entitlement at all.

NHS Annual Leave Entitlement

NHS staff on Agenda for Change terms don’t use the general statutory formula above — they get a more generous, service-based entitlement set out in the Agenda for Change handbook:

These figures are for full-time staff and are pro-rated for part-time colleagues in exactly the same proportional way described in the pro-rata section above. NHS leave years typically run 1 April to 31 March, and new starters partway through the year accrue on a pro-rata basis, so the “New starter / leaver” tab of the calculator above works for NHS staff too — just enter your Agenda for Change figure as the full-year entitlement rather than 28.

Common Mistakes When Calculating Annual Leave

• Confusing hours per day with days per week. Pro-rata entitlement is driven by how many days you work, not how long each of those days is — see the pro-rata section above.
• Using the old pre-2024 case law for irregular hours. If you’re relying on advice from before January 2024, it may reflect the now-superseded Harpur Trust position rather than the current 12.07% accrual rules.
• Forgetting that leave still accrues during sick or family leave. This is one of the most common reasons workers are underpaid on leaving a job.
• Assuming bank holidays are always extra. Check your contract — many UK employers include them inside the 28-day statutory total rather than adding them on top.
• Not rounding correctly. Employers can round entitlement up, but not down — a small detail that matters if your own hand calculation comes out just under a whole number.

Frequently Asked Questions

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