Annual Leave Accrual Calculator Uk

Estimate statutory or custom holiday accrual for UK workers. This calculator covers regular workers paid in days, regular workers paid in hours, and irregular-hours or part-year workers using the 12.07% accrual approach commonly referenced for holiday years starting on or after 1 April 2024.

How an annual leave accrual calculator works in the UK

An annual leave accrual calculator UK is designed to estimate how much paid holiday a worker has built up over time. In the UK, statutory paid annual leave is generally based on 5.6 weeks of leave per leave year. For full-time employees working five days each week, that usually equals 28 days. For part-time staff, the entitlement is usually calculated on a pro rata basis. For irregular-hours and part-year workers, newer rules introduced for holiday years starting on or after 1 April 2024 allow accrual to be calculated at 12.07% of hours worked in the relevant pay period, subject to the legal framework and any enhanced contractual terms.

This matters because annual leave is not just an HR admin task. It affects payroll, staffing, compliance, employee wellbeing, and legal risk. Employers need a consistent system for tracking accrual. Workers need a reliable way to check whether the balance shown on a payslip or HR system makes sense. A good calculator makes the entitlement visible and easier to audit.

Key UK statutory figure: most workers are entitled to 5.6 weeks of paid annual leave each year. For someone working 5 days a week, that is 28 days. Employers can include bank holidays within that total unless the contract gives extra leave on top.

The calculator above supports three common scenarios:

• Regular worker measured in days per week: useful for employees with fixed working days, such as 3 days, 4 days, or 5 days each week.
• Regular worker measured in hours per week: useful where holiday is tracked in hours rather than days, often for shift workers or flexible staff with stable weekly hours.
• Irregular-hours or part-year worker: useful for estimating holiday accrual using the 12.07% approach from hours worked.

Statutory annual leave entitlement in the UK

Under the Working Time Regulations, eligible workers in the UK typically receive a statutory minimum of 5.6 weeks of paid holiday each year. That statutory minimum creates the baseline for most holiday calculations. The practical amount depends on working pattern:

Working pattern	Statutory formula	Total annual leave	Notes
5 days per week	5 × 5.6	28 days	Common full-time benchmark in the UK
4 days per week	4 × 5.6	22.4 days	Part-time entitlement is pro rata
3 days per week	3 × 5.6	16.8 days	Often rounded according to employer policy
2 days per week	2 × 5.6	11.2 days	Still protected by the same statutory rules
1 day per week	1 × 5.6	5.6 days	Useful for casual but regular weekly patterns

There is also an important statutory cap for workers measured in days: 5.6 weeks can be capped at 28 days. That is why someone working six days a week does not normally receive 33.6 statutory days. Instead, the legal minimum is capped at 28 days unless the contract offers more generous terms.

Holiday contracts can be more generous than the statutory minimum. For example, some employers offer 30 days plus bank holidays, or 25 days plus bank holidays. In those cases, a custom entitlement calculator is particularly useful because the legal minimum becomes the floor, not the final answer.

How to calculate annual leave accrual for regular workers

For regular workers, a simple accrual estimate usually involves taking the full-year entitlement and multiplying it by the fraction of the leave year that has been completed. If a worker is entitled to 28 days per year and has completed 6 months of the leave year, the rough accrual is:

28 ÷ 12 × 6 = 14 days accrued

This monthly approach is widely used in payroll and HR because it is easy to understand. It is especially practical when a worker starts part way through a leave year or when a company wants to estimate leave available at a specific date. The calculator above uses this logic for regular day-based and hour-based workers.

Step-by-step method

1. Work out the full-year entitlement in days or hours.
2. Identify how much of the leave year has passed, often in months.
3. Multiply the annual entitlement by the proportion completed.
4. Subtract any holiday already taken.
5. Review the remaining balance and any future leave still to accrue.

For example, if someone works 4 days a week and has only the statutory entitlement, their annual holiday is 22.4 days. If they have completed 3 months of the leave year, they have accrued approximately 5.6 days. If they have already taken 2 days, they have approximately 3.6 days available at that point in the year.

Irregular-hours and part-year workers: the 12.07% accrual method

For holiday years starting on or after 1 April 2024, UK rules permit holiday accrual for irregular-hours and part-year workers at 12.07% of hours worked in a pay period. This is a major area where confusion can arise, because older case law changed how holiday was approached for some workers, and the rules now distinguish more clearly between worker types.

The 12.07% figure comes from the statutory relationship between working time and leave time. Statutory annual leave is 5.6 weeks, and the remaining working year is 46.4 weeks. Dividing 5.6 by 46.4 gives approximately 0.1207, or 12.07%.

Example:

• Hours worked in the pay period so far: 320
• Holiday accrual rate: 12.07%
• Accrued holiday: 320 × 0.1207 = 38.62 hours

This is why many payroll teams now track irregular-hours holiday in hours rather than days. It gives a more precise measure for workers whose shifts vary week to week. If your organisation also uses rolled-up holiday pay for qualifying workers under current rules, that should still be handled carefully to ensure the legal basis is correct and payslip transparency is maintained.

Monthly accrual examples at a glance

Annual entitlement	After 1 month	After 3 months	After 6 months	After 9 months	After 12 months
28 days	2.33 days	7 days	14 days	21 days	28 days
22.4 days	1.87 days	5.6 days	11.2 days	16.8 days	22.4 days
16.8 days	1.4 days	4.2 days	8.4 days	12.6 days	16.8 days
210 hours	17.5 hours	52.5 hours	105 hours	157.5 hours	210 hours

These examples show why the unit matters. If a worker is rostered in long shifts, measuring entitlement in hours may produce a fairer and more accurate outcome than measuring in days. Employers should apply the contract and internal holiday policy consistently across the workforce.

Bank holidays and whether they are included

One of the most common questions in annual leave calculations is whether bank holidays are included within statutory entitlement or added on top. In UK law, an employer can include bank holidays within the 5.6 weeks statutory minimum. That means a worker with “28 days including bank holidays” may still be receiving only the legal minimum if they work five days a week.

However, many employers offer terms such as:

• 20 days plus bank holidays
• 25 days plus bank holidays
• 30 days inclusive of bank holidays

Because contracts differ, the calculator above does not automatically increase entitlement based on bank holidays. Instead, it lets you note whether bank holidays are likely included or separate. This is the safest general approach for an online estimator, because the exact treatment depends on the contract wording and workplace policy.

Why pro rata calculations matter for starters and leavers

When somebody joins or leaves part way through a leave year, the holiday entitlement usually needs to be pro rated. A worker should not normally receive a full year of holiday if they only worked part of the leave year, and equally, they should not lose holiday that they already built up. This is where a calculator is especially valuable.

For new starters

Suppose an employee joins on 1 October and the leave year runs from 1 January to 31 December. They are joining with three months left in the leave year. If the full-year entitlement is 28 days, a simple estimate of the remaining leave is:

28 × 3 ÷ 12 = 7 days

For leavers

If an employee leaves before year end, compare holiday accrued to holiday already taken. If they have taken more than accrued, the employer may have an overpayment position depending on the contract and deductions clause. If they have taken less than accrued, they may need to be paid for untaken statutory or contractual leave on termination.

Common mistakes when using an annual leave accrual calculator UK

• Mixing days and hours: always use the same unit throughout one calculation.
• Ignoring custom contracts: some employers offer more than the statutory minimum, so using 5.6 weeks alone may understate entitlement.
• Forgetting leave already taken: accrual is not the same as available balance.
• Assuming bank holidays are extra: they may be included in the statutory total.
• Applying the wrong method to irregular workers: check whether the person qualifies as an irregular-hours or part-year worker under the newer rules.
• Not checking rounding rules: employers may round to the nearest half-day, nearest hour, or use decimal precision.

Best practice for employers and HR teams

If you manage holiday accrual for staff, it is worth standardising the process. That reduces payroll errors and employee queries. A robust approach usually includes:

1. Defining one leave year and one set of calculation rules.
2. Clarifying whether holiday is recorded in days or hours.
3. Documenting whether bank holidays are included or additional.
4. Applying special rules for irregular-hours or part-year workers where relevant.
5. Reconciling accrual against holiday taken every pay cycle.
6. Retaining records in case of disputes or audits.

Employers should also review holiday pay rules, because accrual and holiday pay are related but not identical. Someone may accrue holiday in days or hours, but the pay they receive while taking leave may depend on how their pay is structured, especially where overtime, commission, or variable pay are involved.

Authoritative UK sources

For up-to-date legal guidance and official information, review these sources:

• GOV.UK: Holiday entitlement and pay
• GOV.UK: Calculate holiday entitlement
• legislation.gov.uk: Working Time Regulations 1998

Final thoughts

An annual leave accrual calculator UK is most useful when it combines legal awareness with practical payroll logic. At a minimum, you need to know the worker type, the contract basis, the unit of measurement, the time worked in the leave year, and any leave already taken. For most regular workers, a proportion-of-year method based on the full annual entitlement provides a solid estimate. For irregular-hours and part-year workers, the 12.07% method may be the more appropriate approach for qualifying holiday years under the current framework.

The calculator on this page is designed to give a fast, practical estimate. It is ideal for HR teams, small business owners, payroll administrators, line managers, and workers checking whether a leave balance looks sensible. For complex cases, enhanced contractual rights, or disputes about holiday pay and entitlement, official guidance and professional advice should always be considered alongside any online calculator.