Pro Rata Annual Leave Calculator UK

If you join or leave a job partway through the year, you do not get a full year’s annual leave, you get a proportion of it. The same is true when you want to know how much leave you have built up so far. This pro rata annual leave calculator works out both. Enter your full-year entitlement and the months you work or have completed, and it shows your pro rata leave in days. It is free, built around the UK 5.6 weeks rule, and updated for 2026/27. To work out your full entitlement for a part-time pattern first, use our pro rata holiday calculator, then bring that figure here. Every tool sits under the main pro rata calculator hub.

What pro rata annual leave is

Annual leave is your paid time off work, and pro rata annual leave is the share of it you are entitled to for part of a leave year. It applies in three everyday situations: starting a job after the leave year has begun, leaving before it ends, and checking how much leave you have accrued at any point during the year.

In each case, your full-year entitlement is split in proportion to the time involved. A new starter who joins halfway through the year is entitled to roughly half their annual allowance. Someone six months into the leave year has built up about half of it. The principle is the same throughout: leave builds steadily, in line with the time you have worked.

How the annual leave calculator works

The calculator has two modes. The starter and leaver mode works out your entitlement for a part-year. You enter your full-year leave in days and the months you will actually work in this leave year, and it returns your pro rata allowance. The accrued mode works out how much leave you have earned so far, based on the months you have already completed since the leave year started.

Both use the same idea of leave building up month by month. You also enter the hours in your working day, so the calculator can express any part-day neatly as hours rather than an awkward decimal. The result updates as you change any figure.

The annual leave formula

Pro rata annual leave is worked out from your full entitlement and the months involved:

Pro rata leave = full-year leave × (months ÷ 12)

On a full-year allowance of 28 days, working seven months of the leave year gives 28 × 7 ÷ 12 = 16.3 days. The same sum works for accrual: six months into the year, you have earned 28 × 6 ÷ 12 = 14 days. Some employers work this out in days rather than months for extra precision, dividing by 365 instead of 12, but the monthly method is the one most people see and it gives a very close figure.

Annual leave for new starters

When you start a job after the leave year has begun, your holiday for that first year is pro-rated to the time you will work. You do not lose out, you simply earn leave from your start date rather than the start of the year. So joining a 28-day employer in month five of their leave year gives you around 18.7 days for the rest of that year, then the full 28 from the next year.

Employers usually round part-days in your favour, and some let new starters book leave before they have technically accrued it, on the understanding it will balance out. Check your contract for how your workplace handles the first year, since policies vary on rounding and early booking.

Annual leave when you leave a job

Leaving partway through the leave year works the same way in reverse. You are entitled to the leave you have accrued up to your final day. If you have taken less than that, the balance is paid to you in your final pay. If you have taken more than you had built up, your employer may deduct the difference.

Working out your accrued leave before you hand in notice helps you plan, whether you want to use the days up before you go or take the payment instead. The accrued mode in the calculator gives you the figure in seconds, and the pay side of a final settlement is covered by our pro rata pay calculator.

How leave builds up through the year

Annual leave does not all arrive on day one. It accrues gradually, usually treated as building up each month you work. On a 28-day allowance, that is roughly 2.33 days a month. Many employers track this monthly accrual so they always know how much leave a member of staff is entitled to take at any given point.

This matters most in your first year and when you leave, the two times your entitlement is not simply the full annual figure. For the rest of the time, once you are settled into a full leave year, you can take your whole allowance as normal without worrying about accrual.

The leave year and how it is set

Your leave year is the twelve-month period your holiday entitlement runs over. It is set by your employer, and it does not have to follow the calendar. Common choices are the calendar year from January, the start of the tax year in April, or your own employment anniversary.

Knowing your leave year matters because pro rata calculations are measured against it. The months you enter into the calculator are the months within that year, not the calendar year, if the two are different. If you are unsure when your leave year starts, your contract or HR team will confirm it.

Annual leave accrued by months worked

The table below shows how leave builds up across the year on a full-time, 28-day allowance. For a different entitlement, the calculator scales it for you.

The build-up is even across the year, so each month adds the same amount. That makes it easy to estimate your accrued leave at any point, then confirm the exact figure with the calculator.

Part-time and pro rata annual leave

Part-time workers get the same 5.6 weeks of annual leave as full-time staff, scaled to their days. Their full-year entitlement is therefore lower in days, for example 16.8 days for a three-day week. That part-time figure is the number you enter as your full-year leave here, and the calculator then pro-rates it for a part-year if you are a starter or leaver.

To work out the part-time entitlement in the first place, our holiday entitlement calculator does it from your days or hours per week. Used together, the two tools cover both halves of the question: how much leave your pattern earns, and how much of it applies to a part-year.

Bank holidays and your annual leave

Whether bank holidays sit inside or on top of your annual leave depends on your contract. There is no legal right to take bank holidays off, and they can be counted as part of your 5.6 weeks. If your entitlement is quoted as 28 days, that often already includes the eight bank holidays. If it is quoted as 20 days plus bank holidays, they are separate.

This affects the figure you enter into the calculator, so use your total annual leave including any bank holidays that form part of it. For part-time staff, bank holidays are usually given as a pro rata share too, in line with the days worked.

Checking your annual leave is right

It is worth checking your entitlement rather than assuming the figure you are given is correct, especially in your first or final year. Take your full-year leave, multiply by the months you work in the leave year, and divide by twelve. Compare that with what your employer has allocated.

If the numbers do not match, ask how the figure was worked out, paying attention to rounding and how bank holidays are treated. Keeping your own record helps at the end of a job, when accrued but untaken leave is paid in your final settlement. For the related figures, our salary calculator and holiday calculator sit alongside this one in the same pro rata calculator hub.

Last updated June 2026 for the 2026/27 year. Annual leave figures are based on GOV.UK and Acas guidance on holiday entitlement and accrual. Results are estimates; your contract and your employer's leave year are the final word on your allowance.