Pro Rata Holiday Hours Calculator
Calculate your exact holiday entitlement in hours for part-time or mid-year starters
This calculator provides an estimate. Always verify with your employment contract or HR department for statutory minimums in your region.
Most people assume their holiday entitlement is straightforward. It isn’t. The moment you add part-time hours, a mid-year start date, or an employer that quotes entitlement in days instead of hours, the whole thing gets complicated fast. What looks like 28 days on a contract means something very different if you work 25 hours a week instead of 37.5.
That’s the gap this calculator closes. Enter your contract hours, your full-time benchmark, and the total entitlement — and you’ll get your pro rata holiday allowance in hours, not vague fractions of a day. If you started partway through the leave year, it handles that accrual calculation too.
Before you use it, though, it helps to understand what the calculator is actually doing under the hood. A lot of payroll disputes and incorrect holiday payouts come from people using the wrong starting number — and that’s a mistake worth avoiding.
What the Calculator Is Actually Doing With Your Numbers
Step-by-Step: How to Get Your Result
- Enter your Contract Hours Per Week — the hours you’re actually contracted to work, not what you usually do.
- Enter the Full-Time Hours Per Week at your workplace — this is the benchmark everything gets measured against, typically 37.5 or 40.
- Enter the Full-Time Holiday Entitlement — the total a full-time employee gets. Use the dropdown to tell the calculator whether that’s expressed in hours, days, or weeks.
- If bank holidays are included in your total entitlement figure, enter those hours separately so the calculator can show you both components clearly.
- If you started partway through the leave year, enter your Employment Start Date and the Holiday Year End Date to calculate the accrual fraction.
- Hit Calculate to see your full pro rata breakdown.
The Formula Your Payroll Team Uses
The core pro rata calculation has two components that get multiplied together. First, your part-time fraction: your contract hours divided by the full-time hours. Then, if applicable, your accrual fraction: days worked in the leave year divided by total days in the leave year.
Breaking Down Each Variable
Your part-time fraction is simply (contract hours ÷ full-time hours). Someone working 30 hours in a 37.5-hour workplace has a fraction of 0.8, or 80%.
The full-time entitlement in hours is what you apply that fraction to. In the UK, the statutory minimum is 5.6 weeks — for a 37.5-hour week, that’s 210 hours. Many employers offer more. If your entitlement is expressed in days, multiply by your daily hours (contract hours ÷ 5) to convert it.
The accrual fraction only applies if you didn’t work the full leave year. It’s (days from your start date to the year end ÷ total days in the leave year). A mid-year starter who joined exactly six months in gets roughly 50% of their pro rata entitlement.
Worked Example: 25 Hours, Mid-Year Starter
Say the full-time week is 37.5 hours, and the full-time entitlement is 224 hours per year (including 56 hours of bank holidays). You work 25 hours a week and started 3 months into the leave year.
Part-time fraction: 25 ÷ 37.5 = 0.6667. Accrual fraction: 9 months remaining ÷ 12 months = 0.75. Full entitlement excluding bank holidays: 168 hours. Pro rata entitlement: 168 × 0.6667 × 0.75 = 84 hours. Bank holidays pro rata: 56 × 0.6667 × 0.75 = 28 hours. Total: 112 hours.
Where Getting This Wrong Actually Costs You
Holiday calculations done purely in days consistently undercount part-time workers who don’t work the same hours every day. Someone working four long days a week and someone working five short days might both show 28 days on paper — but they’re owed very different numbers of hours.
A Common Real-World Situation
A part-time worker doing 20 hours across three days — maybe Monday, Wednesday, Friday — gets told they have 16.8 days of holiday. But 16.8 “days” based on what daily length? If the employer assumes a standard 7.5-hour day but the employee’s actual working day is 6.67 hours, the day-based calculation inflates the entitlement and the employer overpays. Convert everything to hours, and that ambiguity disappears entirely.
What Changes When Your Pattern Shifts
If you change your contracted hours mid-year, the calculation needs to be done in two separate segments — one for each working pattern — then added together. The calculator handles the most common scenario (consistent hours throughout), so for a mid-year hours change, run two separate calculations and combine the results.
Three Inputs That Quietly Throw Off the Result
Using Actual Hours Worked Instead of Contracted Hours
Your holiday entitlement is always based on contracted hours, not the hours you actually clock. If you regularly work 30 hours but your contract says 25, your entitlement is based on 25. Overtime doesn’t count toward the pro rata base unless it’s guaranteed and regular — a nuanced area covered in the UK government’s holiday entitlement guidance.
Misidentifying the Full-Time Benchmark
Some workplaces have different full-time hours by department. Use the figure that applies to your specific role or grade, not a company-wide average. Getting this wrong shifts the entire fraction — and it’s one of the most common errors payroll teams flag when auditing entitlement records.
Counting Bank Holidays Twice
If your employer includes bank holidays within your stated annual entitlement, then pro-rating the total already accounts for them. Separately adding bank holidays on top double-counts them. The calculator lets you split them out specifically for this reason. For context on how bank holidays interact with pro rata rights, Acas has a clear breakdown worth bookmarking.
You might also find our pro rata salary calculator useful if you’re working out what a full-time salary converts to at your contracted hours — the two often come up together when starting a new part-time role.
Questions That Come Up Every Time Someone Runs This Calculation
What’s the minimum holiday entitlement for part-time workers in the UK?
Under UK law, all workers — including part-time — are entitled to at least 5.6 weeks of paid holiday per year, pro rated to their hours. For a 25-hour week against a 37.5-hour full-time benchmark, that’s a minimum of 140 hours (5.6 × 25). Check the latest government guidelines, as the minimum can be updated through legislation.
How do I convert days of holiday into hours?
Multiply the number of days by your average daily working hours. If you work 25 hours across 4 days, your daily hours are 6.25. So 16 days becomes 100 hours. Always base this on your own daily hours, not a generic 7 or 8-hour day.
Does holiday accrue during sick leave?
Yes. In the UK, statutory holiday continues to accrue during sick leave — including long-term absence. Workers can carry over up to four weeks of untaken statutory holiday if they were unable to take it due to illness. This is an area where employment law has evolved significantly, so reviewing current guidance or speaking to an HR professional is advisable.
How is holiday calculated for someone who works variable hours?
For workers with no fixed hours, the 12.07% method has historically been used — though its legal standing has been questioned. The more reliable approach is to calculate entitlement as 5.6 weeks of average weekly hours, averaging over the previous 52 paid weeks. Our irregular hours pro rata calculator can walk you through that separately.
Can I take holiday before it’s fully accrued?
This depends entirely on your employer’s policy. Some employers allow workers to take holiday in advance of accrual; others don’t. If you leave before accruing holiday you’ve already taken, your employer may be entitled to deduct the difference from your final pay — but only if your contract states this explicitly.
How does pro rata holiday work for a term-time worker?
Term-time workers are entitled to the same 5.6 weeks but calculated against their actual working weeks in the year. If you work 38 weeks per year, your entitlement is 5.6 × your weekly contracted hours × (38 ÷ 52). The result is typically rolled into enhanced pay during term time or paid as a lump sum.
Is bank holiday pay different from annual leave pay?
In terms of calculation, bank holiday pay follows the same “normal pay” rules as annual leave — it should reflect your regular earnings, including any regular overtime or commission that forms part of your normal pay. See the official UK bank holiday calendar for dates. The rate of pay is the same; the entitlement source is what differs.
What if my employer quotes entitlement in weeks?
Convert it to hours using your contracted weekly hours. 5.6 weeks for a 30-hour worker is 5.6 × 30 = 168 hours per year. Weeks are the cleanest unit for the underlying law, but hours are the most useful for day-to-day planning. This calculator handles all three formats — just select the right option from the dropdown before entering your figure.
If you’re looking at holiday pay specifically rather than entitlement hours, our pro rata holiday pay calculator takes the hours output from this tool and converts it into a monetary figure based on your hourly rate.
Run the numbers, save the result, and if anything looks off against what your contract or payslip shows, that’s worth a direct conversation with your HR department — armed with the exact formula now in your back pocket.