Annual Leave Accrual Calculator UK
Estimate how much holiday a worker has accrued during the current leave year based on start date, leave year dates, work pattern, and entitlement type. Ideal for employers, HR teams, payroll staff, and employees checking holiday balances.
Your results will appear here
Enter the worker details above, then click Calculate annual leave accrual.
Expert guide to using an annual leave accrual calculator in the UK
An annual leave accrual calculator helps employers and workers estimate how much paid holiday has built up over the course of a leave year. In the UK, holiday entitlement is governed by statutory rules, but the exact way a balance is shown on a payslip, HR platform, rota system, or contract can vary from one employer to another. That is why a calculator is useful. It gives you a quick, structured estimate based on dates, work pattern, and entitlement level.
At the most basic level, annual leave accrual is the proportion of the yearly holiday allowance that has been earned so far. If someone has the legal minimum and is halfway through the leave year, they have generally accrued around half of their annual entitlement, subject to the employer’s rules on rounding and any leave already taken. For starters, leavers, part time workers, and irregular schedules, the picture can be more nuanced, which is where a purpose built annual leave accrual calculator UK tool becomes especially helpful.
How annual leave entitlement works in the UK
Under UK law, workers are entitled to paid annual leave. The statutory minimum is 5.6 weeks per year. For someone working five days a week, that is 28 days. For someone working three days a week, it is 16.8 days. A worker is still entitled to 5.6 weeks if they work fewer days, but the practical amount is scaled to their working pattern.
A key legal figure to remember is the 28 day statutory cap. This applies when entitlement is expressed in days, so someone working six days a week does not simply receive 33.6 statutory days. Their statutory minimum remains capped at 28 days. Employers can, of course, offer more generous contractual holiday if they choose.
Holiday pay also matters. For workers with variable pay, the calculation of holiday pay can involve a 52 week reference period. That rule is separate from accrual itself, but it is often relevant in practice because HR teams want to know both how much leave has accrued and what that leave should be paid at.
| Working pattern | Statutory entitlement | Monthly equivalent | Approx weekly accrual |
|---|---|---|---|
| 1 day per week | 5.6 days | 0.47 days | 0.108 days |
| 2 days per week | 11.2 days | 0.93 days | 0.215 days |
| 3 days per week | 16.8 days | 1.40 days | 0.323 days |
| 4 days per week | 22.4 days | 1.87 days | 0.431 days |
| 5 days per week | 28 days | 2.33 days | 0.538 days |
| 6 days per week | 28 days statutory cap | 2.33 days | 0.538 days |
What an annual leave accrual calculator actually does
A good calculator takes the total annual entitlement and applies a time based proportion. In most cases, it follows this logic:
- Identify the current leave year start date and end date.
- Work out the worker’s annual entitlement in days.
- Check when employment began during that leave year.
- Calculate how much of the relevant period has elapsed by the chosen date.
- Multiply the annual entitlement by that fraction.
- Subtract leave already taken if you want a remaining balance rather than gross accrued leave.
That is exactly why this type of tool is useful for joiners. If someone starts partway through the year, they usually do not receive the full annual leave pot immediately on a pro rata basis unless the employer chooses to front load it. Instead, entitlement builds up according to service during that leave year.
Example of a simple pro rata accrual
Imagine an employee works 5 days per week and receives the statutory minimum of 28 days. Their leave year starts on 1 January. If they joined on 1 April and you want to calculate accrual at 30 June, they have worked for a quarter of the leave year. A rough estimate would be 28 multiplied by 3 divided by 12, giving 7 days accrued. If they have already taken 2 days, their estimated remaining balance would be 5 days.
This calculator uses exact dates rather than rough month blocks, which gives a better estimate for real world HR administration.
Why leave year dates matter so much
Many mistakes happen because people assume holiday always runs from January to December. In reality, employers set their own leave year in contracts or staff handbooks, provided the arrangement is compliant with the law. Common leave year start points include:
- 1 January
- 1 April
- Employment anniversary date
- A business specific financial or academic year point
If your leave year starts on 1 April, a balance checked in August should be measured from April, not from January. Using the wrong start date can materially overstate or understate accrued holiday.
Part time, shifts, and irregular hours
Part time workers should not be treated less favourably. Their entitlement is simply pro rated according to how many days or hours they work relative to the full holiday year. If someone works 3 days each week, statutory leave is 16.8 days. If your business tracks leave in hours rather than days, converting days into hours can improve accuracy. This calculator includes average hours per day so a day based result can also be viewed as an hours estimate.
For irregular hours and some part year workers, holiday calculations can be more complex. Employers may still discuss accrual in percentage terms for internal planning, but they should make sure the final entitlement and holiday pay approach is compliant with current law and guidance. This is one reason HR professionals regularly refer back to official government resources.
Comparison table: how balances can look through the year
The table below shows a 5 day worker on the statutory minimum of 28 days with no leave taken. It illustrates how a balance can build if you estimate using elapsed portions of the year.
| Point in leave year | Share of year elapsed | Accrued leave | Balance if 5 days already taken |
|---|---|---|---|
| 1 month | 8.33% | 2.33 days | 0 days available |
| 3 months | 25% | 7.00 days | 2.00 days |
| 6 months | 50% | 14.00 days | 9.00 days |
| 9 months | 75% | 21.00 days | 16.00 days |
| 12 months | 100% | 28.00 days | 23.00 days |
Common questions about annual leave accrual in the UK
Is holiday accrued from day one?
Yes, workers begin to build entitlement from the start of employment. The practical amount available at any moment depends on how much of the leave year has elapsed and how the employer administers taking leave in advance of accrual.
Do bank holidays change the calculation?
Bank holidays do not automatically sit on top of statutory minimum leave. Employers can include bank holidays within the 5.6 weeks entitlement. The employment contract and workplace policy should explain how this is handled.
What about rounding?
Some employers show balances to two decimal places. Others round to the nearest half day or whole day for practical administration. A consistent policy is important. The calculator includes a rounding option so you can model how an HR system may display balances internally.
Can someone take more leave than they have accrued?
Often yes, if the employer allows it. Some businesses permit employees to book holiday in advance of accrual, particularly permanent staff. If a worker leaves after taking more than they accrued, the employer may address the overuse subject to the employment contract and wage deduction rules.
Best practice for employers and HR teams
- State the leave year clearly in contracts and policies.
- Be explicit about whether bank holidays are included in the annual allowance.
- Use one measurement method consistently, either days or hours.
- Apply the 5.6 week statutory rule correctly for part time workers.
- Track leave taken separately from gross leave accrued.
- Review joiners and leavers carefully to avoid payroll disputes.
- Cross check unusual cases against official guidance.
Official sources worth checking
If you need to verify a tricky case, these official resources are useful starting points:
- GOV.UK: Holiday entitlement and pay
- GOV.UK: Calculate holiday entitlement
- legislation.gov.uk: Working Time Regulations 1998
When to use a calculator and when to get advice
An annual leave accrual calculator UK tool is ideal for routine checks, quick planning, payroll support, manager approvals, and employee self service. It is especially helpful when someone joins during the year, works part time, changes work pattern, or wants a mid year holiday balance estimate.
However, calculators are still models. Real life cases can involve enhanced contractual entitlement, carry over rules, sick leave interactions, family leave, irregular hours reforms, termination calculations, and disputes about holiday pay. In those circumstances, a calculator should be treated as a practical estimate rather than a substitute for legal or HR advice.
Final takeaway
The core rule is simple: UK statutory holiday is 5.6 weeks each year, and accrued leave builds in proportion to time worked during the relevant leave year. The challenge lies in applying that rule correctly to the right dates, work pattern, and policy choices. A well designed calculator saves time, reduces admin mistakes, and gives both employers and workers a clearer picture of what has been earned so far.
Use the calculator above to estimate accrued days, hours equivalent, percentage of entitlement earned, and remaining balance after leave taken. If your workplace uses custom contractual allowances, you can switch from statutory entitlement to a bespoke annual figure and get an instant comparison.