How to Calculate Pro Rata Holidays

Pro Rata Holiday Calculator

Including bank holidays (Standard UK minimum is 28)

function calculateProRata() { var ftDays = parseFloat(document.getElementById('fullTimeDays').value); var ftHours = parseFloat(document.getElementById('fullTimeHours').value); var ptHours = parseFloat(document.getElementById('partTimeHours').value); if (isNaN(ftDays) || isNaN(ftHours) || isNaN(ptHours)) { alert("Please enter valid numbers for all fields."); return; } if (ftHours <= 0) { alert("Full-time hours must be greater than 0."); return; } // Calculation Logic // Step 1: Calculate the ratio of part-time to full-time var ratio = ptHours / ftHours; // Step 2: Calculate pro rata days var proRataDays = ratio * ftDays; // Step 3: Calculate pro rata hours (Holiday days * hours per day) // Assuming 'full time days' implies a standard working day length derived from weekly hours // Average hours per day for a full timer = ftHours / 5 (Standard assumption) // However, a safer way to calc total holiday hours is: (ProRataDays / ftDays) * (ftDays * (ftHours/5))? // Simplified: (PartTimeHours / FullTimeHours) * (Total Holiday Hours for Full Time) // Total Holiday Hours for Full Time = ftDays * (ftHours / 5). Note: This assumes 5 day week. // Let's use a direct hours calculation for accuracy: // ProRataDays * (Average day length for this employee) // Average day length for employee = ptHours / (Days worked). We don't have days worked. // Alternative precise hours calc: // The entitlement in hours is simply the percentage of the full time equivalent in hours. // Full time annual holiday hours = ftDays * (ftHours / 5); (Assuming 5 day work week is the divisor for 'Days') // This is standard practice in UK/EU HR. var standardDaysPerWeek = 5; var fullTimeHolidayHours = ftDays * (ftHours / standardDaysPerWeek); var proRataHolidayHours = ratio * fullTimeHolidayHours; // Display Results // Round to 1 decimal place for neatness, though payroll may use 2 document.getElementById('resultDays').innerHTML = proRataDays.toFixed(1) + " Days"; document.getElementById('resultHours').innerHTML = proRataHolidayHours.toFixed(1) + " Hours"; document.getElementById('resultsArea').style.display = "block"; }

What is Pro Rata Holiday?

Pro rata holiday refers to the calculation of holiday entitlement for employees who work fewer hours than a standard full-time employee. "Pro rata" is a Latin term meaning "in proportion." This ensures that part-time staff receive a fair amount of paid leave that is directly proportional to the hours they work compared to a full-time equivalent.

In many jurisdictions, including the UK and EU, it is a legal requirement to treat part-time workers no less favourably than full-time workers, which implies their holiday allowance must be calculated using this proportional method.

How to Calculate Pro Rata Holiday Entitlement

Calculating pro rata holidays involves determining the ratio of hours a part-time employee works compared to a full-time contract, and applying that same ratio to the annual holiday allowance.

The standard formula used by HR professionals is:

(Employee's Weekly Hours ÷ Full-time Weekly Hours) × Full-time Annual Holiday Days

Example Calculation

Let's look at a practical example using the formula above:

• Full-time entitlement: 28 days (standard statutory minimum in the UK including bank holidays).
• Full-time hours: 40 hours per week.
• Employee's hours: 24 hours per week (Part-time).

The math would look like this:

1. Divide 24 (employee hours) by 40 (full-time hours) = 0.6
2. Multiply 0.6 by 28 (full-time days) = 16.8 days

In this scenario, the part-time employee is entitled to 16.8 days of paid annual leave.

Calculations for Casual or Zero-Hours Workers

For employees with irregular hours or zero-hour contracts, calculating holiday entitlement at the start of the year can be difficult. In these cases, the "accrual" method is often used (where laws permit).

Commonly, holiday is calculated as a percentage of hours worked. Based on the statutory 5.6 weeks (UK standard) out of a 52-week year:

• 5.6 weeks holiday ÷ 46.4 working weeks = 12.07%

This means for every hour worked, the employee accrues approximately 7 minutes of holiday pay, or 12.07% of their hours worked.

Bank Holidays and Part-Time Work

A common question is whether part-time workers get bank holidays off. This depends on whether they are scheduled to work on the day the bank holiday falls.

However, to avoid unfair treatment, most companies give a pro-rata allowance of bank holidays. This is why it is best practice to include bank holidays in the total annual entitlement figure (e.g., using 28 days total instead of 20 days + 8 bank holidays) when performing the calculation. This ensures that a part-time worker who never works Mondays (when most bank holidays fall) still gets their fair share of paid leave entitlement to take at other times.

Frequently Asked Questions

Can I round down holiday entitlement?

No. You cannot round down statutory holiday entitlement. If the calculation results in a fraction (e.g., 16.8 days), you can either leave it as a fraction or round it up to the nearest half or full day. Rounding down would result in giving the employee less than their legal minimum.

Does the calculation change for shift workers?

For shift workers who work different hours each week, it is often easier to calculate holiday entitlement in hours rather than days. The calculator above provides an hourly entitlement figure which is calculated by determining the total annual holiday hours of a full-time worker and applying the pro-rata percentage.