Holiday Calculator: How to Calculate It Correctly

Get the calculation right first

Before reaching for a template, be clear about which of the three common calculations you actually need, because they are not interchangeable.

Full-year entitlement for a standard week: 5.6 weeks × days per week. Five days gives 28, four days gives 22.4, three days gives 16.8. This is gov.uk holiday entitlement guidance.

Mid-year starter or leaver: the full-year figure scaled by the proportion of the leave year worked. Round up, never down — rounding statutory entitlement down is unlawful.

Irregular hours: switch to hours entirely. Weekly hours × 5.6 gives an hours-based allowance, and bookings deduct actual hours. This is the only approach that stays correct when the pattern changes mid-year.

Pick the right one, then worry about the spreadsheet.

A worked example: what actually carries over

UK statutory leave splits into two parts, and they behave differently. Of the 5.6 weeks in gov.uk holiday entitlement guidance, four weeks derive from retained EU-era working time rules and 1.6 weeks are the domestic addition.

An employee with the statutory 28 days has 12 days remaining on 31 December. Your policy allows five days of carry-over.

They carry five days into January, and 7 days lapse. That is lawful for the 1.6-week portion, which can be restricted, but the four-week portion carries stricter protections: it generally cannot simply be extinguished if the worker was prevented from taking it — for example through sickness absence or because the employer never gave them a genuine opportunity to take it. Acas guidance is the practical reference here, and this is exactly the point where you should take advice rather than rely on a policy template.

The operational lesson is narrower and more useful: a December balance of 12 days was visible in October, and in September. Carry-over disputes are almost never a December problem. They are a September problem that nobody looked at.

Run the check in Q3. Anyone sitting above roughly half their allowance with a quarter of the year left needs a conversation, not a policy.

Building the template

A usable template needs one row per employee and these columns: contracted days or hours per week, start date, leave year start, calculated entitlement, bank holiday treatment, days taken, days booked but not yet taken, and remaining.

The column people omit is "booked but not yet taken", and its absence is the single most common cause of an over-booked balance. Someone with 5 days left and 4 already booked for August has 1 day available, not 5. If the sheet only tracks days taken, it will happily let them book a week.

Two other guards worth adding: a flag when remaining goes negative, and a flag when remaining exceeds the carry-over cap with less than a quarter of the leave year to run. The second one is how you avoid a December problem.

Checking your numbers against reality

A calculation that is arithmetically correct can still be operationally wrong, and the way to find out is to test it against your awkward cases rather than your typical one.

Pick four people deliberately: someone full-time, someone part-time on fixed days, someone who joined mid-year, and someone whose pattern changed during the year. Run each through the template and check the output against what they believe they have.

The fourth case is where most templates break. Someone who moved from three days to five days a week in June has entitlement in two parts — 5.6 × 3 for the portion of the year on the old pattern, 5.6 × 5 for the remainder — and a single "days per week" column cannot express that. Either split them into two rows or convert the whole calculation to hours.

Disagreements between the sheet and the employee are worth chasing rather than overriding. The employee is often right, because they have been counting their own days all year and the sheet has been edited by three people.

When the spreadsheet stops being the right answer

A spreadsheet is genuinely fine at five people. The failure point is not size exactly — it is concurrency. The moment more than one person edits it, or more than one manager approves against it, the sheet stops being a record and becomes a rumour.

The specific symptoms: two people booked the same week and nobody noticed until the week arrived; the balance in the sheet disagrees with what someone believes they have; a leaver’s final balance takes an hour to reconstruct.

At that point the sheet is no longer saving money. It is deferring an hour of finance work into the most expensive possible moment.

Where LeaveKit fits

LeaveKit is a leave management tool for UK teams of roughly 5 to 50 employees, and it is worth being precise about what it does and does not do.

What it does: month, week, 30-day and day views with department filter, hover detail cards, holiday and birthday markers; date range with half-day start/end and live working-day calculation; and — the part that motivated it — warns at booking time when teammates are already off on the same dates (/api/leave/conflicts). It also handles overtime entry logging at /toil, converts logged hours into toil balance, CSV reporting, an iCal subscription feed, and public holiday calendars for 11 countries with the UK dates checked against gov.uk for 2026 to 2028.

What it does not do, stated plainly because buying decisions are made on the gaps: there is no Slack integration, no two-way Google or Outlook calendar sync (the iCal feed is one-way), no payroll or Xero connector, no public API, and no SSO. The mobile app is built but not yet released. If any of those are requirements today, LeaveKit is not the right tool for you yet.

Commercially, LeaveKit is in early access with a 30-day free trial and no card required. Public pricing is not published yet. You can also open the demo workspace without signing up at all, which is the fastest way to judge whether the wall chart matches how your team actually thinks about coverage.

Frequently asked questions

How do I calculate holiday entitlement for a part-time employee?

Multiply 5.6 weeks by the number of days they work per week. Three days a week gives 5.6 × 3 = 16.8 days; four days gives 22.4. Do not scale 28 days by intuition, and do not round down — statutory entitlement may be rounded up but never down. If the working pattern is irregular, convert to hours instead: weekly hours × 5.6 gives an hours-based allowance that stays correct when the pattern changes.

How much holiday are UK employees legally entitled to?

The statutory minimum is 5.6 weeks of paid holiday per leave year, according to gov.uk holiday entitlement guidance. For someone working five days a week that is 28 days, and employers are permitted to count the eight UK bank holidays within that total rather than in addition to it. Part-time employees get 5.6 weeks of their own working week: three days a week gives 16.8 days. The contract must state whether bank holidays are included.

Can an employer refuse a holiday request?

Yes, an employer can decline a specific request, subject to notice requirements. What an employer cannot do is operate in a way that prevents someone taking their statutory entitlement at all. In practice, a refusal is far easier to defend when it comes with a concrete reason — a stated minimum cover level for that team on those dates — than when it is attributed to unspecified operational requirements. Acas publishes guidance on handling refusals.

What happens to holiday that has not been taken by the end of the leave year?

That depends on your policy and on which part of the entitlement is involved. Of the 5.6 weeks, 1.6 weeks can generally be restricted more tightly, while the four-week portion carries stronger protections — particularly where someone was prevented from taking it through sickness or because they were never given a real opportunity. Set a carry-over cap in policy, and run a balance check in the third quarter rather than in December.

Is LeaveKit free?

LeaveKit is in early access with a 30-day free trial and no card required. There is no permanent free tier and public pricing has not been announced yet. The trial is the full product: wall chart, booking with half-days, conflict warnings, approvals, TOIL logging, CSV reports and public holiday calendars. There is also a demo workspace at /demo that needs no sign-up at all.

Try it on a real month

The fastest way to judge any leave tool is to run one real month through it. LeaveKit has a demo workspace that needs no sign-up, and a 30-day trial with no card required.

Open the demo workspace · Start a 30-day trial