Working Out & Calculating Pro-Rata Holiday Entitlement

If you need to calculate pro rata holiday entitlement for part-time staff, new starters, leavers, or irregular-hours workers, the key is to start with the UK statutory minimum of 5.6 weeks’ paid holiday or that outlined in your contracts of employment if above the statutory minimum and then adjust it fairly to reflect the working time and time served. For UK businesses, the challenge is rarely the principle itself; it is applying it consistently across different contracts, working patterns, and bank holiday arrangements without creating confusion or risk.

In this guide

This guide explains how to work out pro rata holiday entitlement for common employee types, including part-time workers, employees who join or leave mid-year, and irregular-hours workers. It also covers bank holidays, accrual, rounding, holiday pay, carry-over, and practical ways to make your internal process clearer and easier to manage.

Key takeaways

• UK workers are generally entitled to a minimum of 5.6 weeks’ paid annual leave each year, whether they work full time, part time, or under a zero-hours contract.
• To calculate pro rata holiday entitlement in days, multiply the number of days worked each week by 5.6.
• Part-time employees must not be treated less favourably than full-time employees, so any enhanced holiday allowance should also be applied on a pro rata basis.
• Holiday starts accruing from day one of employment, including during probation, sick leave, and statutory family leave.
• Statutory holiday is capped at 28 days, even where someone works more than five days a week.
• Employers should not round holiday entitlement down, and part-days need to be handled fairly and clearly in policy and practice.
• For irregular-hours workers, holiday entitlement is often tracked in hours, and holiday pay is based on average pay over the previous 52 paid weeks.

What pro rata holiday entitlement means

Pro rata means “in proportion”. In practice, it is the method used to calculate annual leave for employees whose working pattern or time in employment does not match your full-time, full-year baseline.

This usually applies where someone works part time, joins part way through the leave year, leaves before the leave year ends, works on a fixed-term contract, or works irregular hours. In each case, the employee still has a right to paid holiday, but the entitlement is adjusted so it reflects what they actually work rather than a standard full-time pattern.

The statutory rule every employer starts with

Under UK law, workers are entitled to 5.6 weeks’ statutory paid holiday a year. For someone who works five days a week, that equates to 28 days’ leave, and that 28-day statutory entitlement includes the legal cap even if the employee works six days a week.

Bank holidays can be included within the 5.6 weeks or offered in addition, depending on your contract terms. Many employers choose to offer more than the statutory minimum for recruitment, retention, and employee wellbeing reasons, but if you do that, you need to apply the enhanced entitlement fairly to part-time staff too.

How to calculate pro rata holiday entitlement for those that receive the statutory minimum

Part-time employees on regular days

The standard method is straightforward: multiply the number of days worked each week by 5.6. So if an employee works three days a week, their statutory annual leave is 16.8 days.

A worker on two days a week would receive 11.2 days, and someone on 2.5 days a week would receive 14 days. Where the calculation creates part-days, employers should not round the entitlement down, and they should explain clearly how part-days can be taken.

Employees whose holiday is tracked in hours

For employees with variable shift lengths, calculating holiday in hours is often more practical than using days. In those cases, multiply the weekly hours worked by 5.6 to get the annual statutory entitlement in hours.

For example, if an employee works 30 hours per week, their statutory entitlement would be 168 hours a year. This approach is particularly useful where staff work compressed hours, half-days, or uneven shift patterns across the week.

New starters and leavers

Employees begin accruing holiday from day one of employment. If someone starts or leaves part way through the leave year, their entitlement should be reduced proportionally to reflect the part of the holiday year they will actually work.

A common practical method is to divide the full-time annual leave entitlement with 365 days (days in a full year) and multiply this by the actual number of days employed in the holiday leave year. For example, if a full-time employee is entitled to 28 days a year, and they have been employed for 104 days of the current holiday year, they have accrued around 8 days of leave when rounded up.

Irregular-hours and zero-hours workers

Irregular-hours workers also have statutory holiday rights, but the way employers track those rights is usually different. A commonly used accrual method is 12.07% of hours worked, which converts hours worked into holiday hours earned.

For example, if a worker completes 30 hours, they accrue 3.62 hours of holiday using the 12.07% method. When that leave is taken, holiday pay for irregular-hours and part-year workers is based on average pay over the previous 52 paid weeks.

Worked examples

These examples show how to work out pro rata holidays in practice using the statutory minimum of 5.6 weeks.

For small businesses, examples like these are useful because they create a repeatable internal rule rather than forcing managers to make ad hoc judgements. They also help reduce inconsistencies between payroll, line managers, and employee handbooks.

Bank holidays and pro rata leave

There is no automatic statutory right for employees to have bank holidays off in addition to annual leave. Whether bank holidays are included in holiday entitlement or given on top depends on the employment contract and your company policy.

This is where part-time calculations can become sensitive. If a business only grants paid time off for bank holidays that fall on an employee’s usual working days, part-time staff can be disadvantaged depending on their working pattern, so many employers prefer to convert bank holiday entitlement into an overall annual allowance in days or hours to support fairness.

Holiday accrual, carry-over, and special leave

Holiday continues to accrue during sick leave and statutory family leave, including maternity, paternity, adoption, and shared parental leave. That means employees should not lose their right to build up annual leave simply because they are away from work on protected leave.

Carry-over rules can depend on policy and circumstances, but there are recognised situations where unused holiday can roll forward, particularly where sickness or statutory leave has prevented the worker from taking it. Acas also states that where an employer has not properly given the worker the opportunity to take leave, or encouraged them to do so, some leave may carry over.

Holiday pay and why it matters

Calculating entitlement is only part of the picture; employers also need to pay holiday correctly. For workers with irregular hours or part-year patterns, holiday pay is based on average pay over the previous 52 paid weeks, rather than simply paying a flat current-week figure.

This matters because getting the entitlement right but the pay wrong can still create employee relations issues and legal exposure. For many businesses, the safest approach is to align HR records, payroll settings, and holiday policy wording so the entitlement calculation and the payment method support each other.

A practical audit checklist for employers

A useful way to improve on standard guidance is to treat holiday entitlement as a process issue, not just a calculation exercise. Many businesses have the right formula on paper but still create problems through inconsistent contracts, unclear handbook wording, or managers applying different rules across teams.

A practical internal audit should check the following:

• Whether full-time entitlement is clearly defined in contracts and handbooks, including whether bank holidays are included.
• Whether part-time and flexible workers receive pro rata access to any enhanced holiday allowance.
• Whether holiday is tracked in the most appropriate unit, days for fixed patterns and hours for variable ones.
• Whether rounding rules for part-days are documented and applied consistently.
• Whether payroll uses the correct 52-week reference method where holiday pay varies.
• Whether starters and leavers are checked against the leave year rather than the calendar year.

Common mistakes businesses make

Even where the rules look simple, errors often happen in the detail. Common examples include rounding down part-day entitlements, forgetting to pro rate enhanced holiday allowances, failing to account properly for bank holidays for part-time staff, and treating holiday pay as basic pay only where average-pay rules should apply.

Another frequent issue is relying on informal manager discretion instead of a written approach. For businesses, especially SMEs, having a clear policy and a documented calculation method is often just as important as the calculation itself.

FAQs

How do you work out pro rata holiday entitlement?

In most cases, you calculate pro rata holiday entitlement by taking the employee’s normal working week and multiplying it by 5.6 weeks of statutory annual leave or the leave entitlement determined in the contract of employment if enhanced. If they work in days, use days; if they work in hours, use hours.

How do I work out pro rata holidays for a part-time employee who are entitled to the statutory minimum annual leave allowance?

Multiply the number of days the employee works each week by 5.6. For example, a part-time employee working three days a week is entitled to 16.8 days’ paid holiday a year.

How do you work out pro rata holiday for someone who starts mid-year?

Work out the proportion of the leave year they will be employed for, then apply that proportion to their full annual entitlement.

How do you calculate pro rata annual leave in hours for those entitled to the statutory minimum annual leave allowance?

Multiply the employee’s weekly hours by 5.6 to calculate annual statutory entitlement in hours. If the worker has irregular hours, employers often track holiday earned as a percentage of hours worked and calculate holiday pay using the 52-paid-week average.

Do part-time employees get bank holidays?

Not automatically as an extra entitlement. Whether bank holidays are included in annual leave or offered in addition depends on your contracts and policy, but part-time employees should be treated fairly and not less favourably than comparable full-time employees.

Do employees accrue holiday while off sick or on maternity leave?

Yes. Holiday continues to accrue during sick leave and statutory family leave, including maternity, paternity, adoption, and shared parental leave.

Can employers round pro rata holiday down?

No, employers should not round down holiday entitlement where part-days arise.