Working out annual leave should take two minutes, not an afternoon. A holiday entitlement calculator removes most of the arithmetic, but it still helps to know what sits behind the numbers, so you can spot a wrong answer and explain a right one.
The difficulty is that no two teams look alike. A full-timer on five days, a part-timer on three, someone paid by the hour, and a new starter who joined in October all need a slightly different sum. Get one wrong and you are having an awkward conversation about somebody's time off.
The 5.6 rule behind every holiday entitlement calculator
Almost every UK holiday entitlement calculator is built on one multiplier. Statutory paid holiday is 5.6 weeks a year, and you get someone's allowance in days by multiplying the days they work each week by 5.6 (source: GOV.UK — Holiday entitlement). Checked 10 September 2026.
| Days worked each week | Statutory entitlement |
|---|---|
| 1 day | 5.6 days |
| 2 days | 11.2 days |
| 3 days | 16.8 days |
| 4 days | 22.4 days |
| 5 days | 28 days |
The statutory maximum is 28 days, so someone working six days a week is still entitled to 28 rather than 33.6. Fractional days look untidy, which is why many employers round up, but the calculation is genuinely that simple.
What the rule cannot tell you is how bank holidays fit in. Some contracts count them inside the allowance, others add them on top. That is a contract question rather than a maths one, and no calculator can answer it for you - check the wording before you confirm a number to a member of staff.
Working in hours rather than days
Hourly paid staff, shift patterns and unusual working weeks need the other formula:
(weekly hours ÷ full-time weekly hours) × full-time days entitlement × hours in a full-time day = hours of holiday.
A worked example. Full-time is 37.5 hours over five days, entitlement is 28 days, and a full day is 7.5 hours. Someone works 30 hours a week:
- 30 ÷ 37.5 = 0.8
- 0.8 × 28 days = 22.4 days
- 22.4 × 7.5 hours = 168 hours
That person has 168 hours of holiday for the year. Expressing entitlement in hours is far easier for variable shifts, because you deduct the hours actually booked instead of arguing about whether a Tuesday counts as half a day. A good calculator will give you the answer in either unit - pick the one that matches how you record absence, then stay with it.
Starters, leavers and part-year entitlement
A full leave year is the easy case. Part of one is where mistakes creep in, whether somebody joined in March or handed in their notice in August. In both situations you award what they built up over the part of the year they were employed, not the full annual figure.
There is a separate rule for irregular-hours and part-year workers. For leave years beginning on or after 1 April 2024, they accrue holiday at 12.07% of the hours actually worked in each pay period (source: GOV.UK — Holiday pay and entitlement reforms). Checked 10 September 2026.
That one catches people out, because it accrues every pay period rather than being set once a year. Doing it by hand twelve times a year for every casual member of staff is where a spreadsheet quietly drifts out of date.
What a holiday entitlement calculator needs from you
Have these six things to hand and any calculator will give you an answer in a few clicks:
- The days or hours the person works each week
- The full-time working week, in hours
- Your full-time allowance, and whether it includes bank holidays
- The hours in a full-time day
- Their start date, or last day if they are leaving
- Whether the contract gives more than the statutory minimum
Get those right and the arithmetic looks after itself, for a full leave year or a pro-rata figure part way through one.
Entitlement and holiday pay are not the same thing
Entitlement is how much time off someone has. Holiday pay is what reaches their bank account while they take it. They are separate calculations and separate problems.
The calculator handles the allowance. Payroll handles the pay. If you are dealing with a leaver who has untaken leave, or somebody whose pay varies with overtime, check with whoever runs your payroll before you promise a final figure.
Record keeping matters here too. Holiday disputes almost always come down to whether accrual was tracked properly at the time, and a clear record of what was owed, booked and taken settles most of them before they start.
Where the arithmetic usually goes wrong
- Applying 5.6 to hours instead of days. The multiplier works on days per week; hourly staff need the hours formula.
- Giving a mid-year starter a full year's allowance. They accrue for the part of the year they worked.
- Assuming bank holidays are always extra. That depends entirely on the contract.
- Forgetting to recalculate after a change in hours. Five days to four changes the entitlement from the date it takes effect.
- Mixing days and hours. 28 days and 210 hours can be the same allowance in a 37.5-hour week.
- Running it all from one shared spreadsheet. Two people approving leave from the same file is where balances start disagreeing.
Using the free HR Henry holiday entitlement calculator
Our free holiday entitlement calculator covers the cases that trip people up: full-time, part-time and pro-rata, mid-year starters and leavers, and the 12.07% method for irregular hours. Give it a start date, weekly hours or a leaver's last day and it returns a figure for a full leave year or part of one.
It is free, there is no sign-up, and the honest use for it is checking your own arithmetic. If your spreadsheet and the calculator disagree, one of them is wrong and it is worth knowing which before somebody books time off they have not got.
If you are tracking leave for a whole team, a calculator is the starting point rather than the destination. Holding entitlement, bookings, sickness and attendance in one place is what keeps the numbers right as people join, leave and change their hours - there is more on that in our guide to what HR software costs and how to roll it out, and on how long to keep employee records.
Frequently asked questions
How do I work out holiday entitlement in the UK?
Multiply the number of days someone works each week by 5.6. Five days a week gives 28 days; three days a week gives 16.8. If you pay by the hour, use the hours formula instead, or put the figures into a holiday entitlement calculator and check the result against the rule.
What is my holiday entitlement if I work part-time?
It is worked out pro rata on the same 5.6 multiplier. Two days a week gives 11.2 days. Check whether your contract includes bank holidays inside that figure or adds them on top, because that decides how much you can actually book.
How many days holiday do I get for a 37.5 hour week?
A 37.5-hour week is normally five days, so the days rule applies: 5 x 5.6 = 28 days. In hours that is 28 x 7.5, or 210 hours. Both describe the same allowance, which is why mixing the two units causes so much confusion.
How do I work out holiday for someone leaving mid-year?
Give them the portion of the leave year they actually worked, not the full annual figure. A holiday entitlement calculator that asks for a leaver's last day will return the pro-rata amount. For irregular-hours and part-year workers the 12.07% method applies instead.
Does a holiday entitlement calculator handle bank holidays?
It works out the statutory allowance. Whether bank holidays sit inside that allowance or on top of it is a contract question, not a maths one, so check the wording before you confirm a figure to anyone.
Do I have to give exactly 5.6 weeks?
That is the statutory minimum, not a cap. Plenty of employers offer more, and if your contract does, the extra is contractual leave on top - so put your own allowance into the calculator rather than assuming 28 days.