Pro-Rata Holiday Entitlement: How It Works & How to Calculate It
Pro-rata holiday entitlement means your leave is proportional to the time you've worked — either because you work part-time, started mid-year, or are leaving before the holiday year ends.
The pro-rata formula
Entitlement = (days worked in year / total working days in year) × 28
Example: starting mid-year
You join on 1 October in a January–December holiday year. You're working for 65 out of 260 working days that year. Pro-rata entitlement = 65/260 × 28 = 7 days.
Example: leaving mid-year
You've accrued 14 days by July but only taken 10. Your employer must pay out the remaining 4 days in your final salary.
Part-time workers
A 3-day week worker gets 3/5 × 28 = 16.8 days. Most employers round up to the nearest half-day.
Why entitlement is really measured in weeks
The statutory entitlement is 5.6 weeks, not 28 days. The 28 figure is simply 5.6 weeks multiplied by a five-day week, and it stops being the right number the moment someone does not work five days.
Thinking in weeks resolves most part-time disputes instantly. A three-day-a-week worker is entitled to the same 5.6 weeks off as a full-timer. Their week is three days, so 5.6 × 3 = 16.8 days. They have not been given less holiday, they have been given the same holiday measured in their own working pattern.
Rounding: up, not down
Pro-rata calculations almost never produce a whole number. Employers may round up or offer part days, but rounding down takes the worker below their statutory minimum and is not permitted.
So 16.8 days can be given as 16.8, or rounded up to 17, but not reduced to 16. Where a contract gives more than the statutory minimum, the employer has more freedom over rounding the additional portion.
Irregular hours and zero-hours workers
For workers with no fixed pattern, the older approach of accruing 12.07% of hours worked was found to underpay some workers and the rules have since changed. For leave years beginning on or after 1 April 2024, holiday for irregular-hours and part-year workers accrues at 12.07% of hours worked in each pay period, and employers may use rolled-up holiday pay paid as an uplift alongside normal wages.
If your hours vary and you are unsure which basis applies to you, the start date of your employer's leave year is the thing that determines it.
Worked example: leaver with untaken leave
Full-time worker on 28 days, leave year running January to December, leaving on 31 July having taken 10 days.
- Proportion of the year worked: 7 months of 12, or 0.583
- Accrued entitlement: 28 × 0.583 = 16.33 days
- Already taken: 10 days
- Payable on termination: 6.33 days, paid at the normal rate of pay
If the worker had instead taken 20 days, they would have used more leave than accrued. An employer can only reclaim that overpayment if the contract expressly allows it, which is why the clause exists in most contracts.
What holiday pay should be worth
Holiday pay is based on normal remuneration, not just basic salary. For workers whose pay varies, it is calculated from average pay over a 52-week reference period, ignoring weeks with no pay and counting back further to make up the 52.
Regular overtime, commission and shift premiums generally count towards that average. Excluding them is one of the more common ways holiday pay is underpaid, particularly for workers who routinely do overtime.
Work out your own figure
Our pro-rata holiday calculator handles all these scenarios automatically, and the part-time entitlement calculator works directly from your days per week.
General information, not legal advice. Statutory entitlement is a minimum and your contract may provide more. ACAS offers free impartial guidance if you believe you are receiving less than the legal minimum.