.calc-container {
max-width: 600px;
margin: 20px auto;
padding: 25px;
background-color: #f9f9f9;
border: 1px solid #ddd;
border-radius: 8px;
font-family: Arial, sans-serif;
box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}
.calc-header {
text-align: center;
margin-bottom: 20px;
color: #2c3e50;
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box; /* Ensures padding doesn't affect width */
font-size: 16px;
}
.calc-btn {
width: 100%;
padding: 12px;
background-color: #27ae60;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
cursor: pointer;
transition: background-color 0.3s;
}
.calc-btn:hover {
background-color: #219150;
}
.result-box {
margin-top: 20px;
padding: 15px;
background-color: #e8f6f3;
border: 1px solid #a9dfbf;
border-radius: 4px;
display: none;
}
.result-value {
font-size: 24px;
font-weight: bold;
color: #27ae60;
text-align: center;
margin-top: 10px;
}
.error-msg {
color: #c0392b;
text-align: center;
margin-top: 10px;
display: none;
}
.article-content {
max-width: 800px;
margin: 40px auto;
font-family: Arial, sans-serif;
line-height: 1.6;
color: #333;
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #ecf0f1;
padding-bottom: 10px;
}
.article-content p {
margin-bottom: 15px;
}
.article-content ul {
margin-bottom: 20px;
padding-left: 20px;
}
.article-content li {
margin-bottom: 8px;
}
.example-box {
background-color: #f0f4f8;
padding: 15px;
border-left: 4px solid #3498db;
margin: 20px 0;
}
function calculateProRata() {
var ftLeave = parseFloat(document.getElementById('ft_leave').value);
var ftHours = parseFloat(document.getElementById('ft_hours').value);
var ptHours = parseFloat(document.getElementById('pt_hours').value);
var months = parseFloat(document.getElementById('months_worked').value);
var errorDiv = document.getElementById('error_msg');
var resultBox = document.getElementById('result_box');
// Reset display
errorDiv.style.display = 'none';
resultBox.style.display = 'none';
// Validation
if (isNaN(ftLeave) || isNaN(ftHours) || isNaN(ptHours) || isNaN(months)) {
errorDiv.innerHTML = "Please fill in all fields with valid numbers.";
errorDiv.style.display = 'block';
return;
}
if (ftHours <= 0) {
errorDiv.innerHTML = "Full-time hours cannot be zero.";
errorDiv.style.display = 'block';
return;
}
// Calculation Logic
// 1. Calculate the ratio of part-time to full-time
var fteRatio = ptHours / ftHours;
// 2. Calculate total annual entitlement based on hours
var annualEntitlementDays = ftLeave * fteRatio;
// 3. Adjust for portion of the year worked (if not 12 months)
var proRataDays = annualEntitlementDays * (months / 12);
// 4. Calculate equivalent in hours (often useful for irregular shifts)
// Average day length for this employee = ptHours / 5 (assuming 5 day week standard)
// OR simply: (Entitlement Days / FT Days) * PT Hours * 52?
// Better approach for hours: (ProRataDays) * (Hours per day of a FT worker)
// Standard assumption: FT worker works ftHours / 5 days a week.
var hoursPerDayFT = ftHours / 5;
var proRataHours = proRataDays * hoursPerDayFT;
// Display Results
var resultDaysText = proRataDays.toFixed(1) + " Days";
// If the result is very close to a whole number, display clean integer
if (Math.abs(proRataDays – Math.round(proRataDays)) < 0.01) {
resultDaysText = Math.round(proRataDays) + " Days";
}
document.getElementById('result_days').innerHTML = resultDaysText;
document.getElementById('result_hours').innerHTML = "(Approx. " + proRataHours.toFixed(1) + " hours)";
resultBox.style.display = 'block';
}
How to Calculate Holidays Pro Rata
Calculating holiday entitlement for part-time staff or employees who start partway through the year can be confusing. The term "pro rata" essentially means "in proportion." It ensures that employees receive a fair amount of leave based on the hours they actually work compared to a full-time equivalent (FTE).
Whether you are an employer ensuring compliance with labor laws or an employee checking your contract, understanding the math behind pro rata holidays is essential. This guide breaks down the calculation method used in our tool.
The Pro Rata Formula
The standard way to calculate holiday entitlement for part-time workers is to apply the ratio of their contracted hours to the company's full-time hours.
The Basic Formula:
(Part-Time Hours ÷ Full-Time Hours) × Full-Time Holiday Allowance = Pro Rata Entitlement
For example, if a full-time employee works 40 hours a week and gets 28 days of leave, a part-time employee working 20 hours would be calculated as:
- Ratio: 20 ÷ 40 = 0.5 (50%)
- Calculation: 0.5 × 28 days = 14 days
Starting or Leaving Partway Through the Year
If an employee joins or leaves the company in the middle of the leave year, their holiday entitlement must be pro-rated further based on the time they were employed.
The calculator above includes a "Duration Worked" field. The math for this adjustment is:
Annual Pro Rata Entitlement × (Months Worked ÷ 12)
For example, if the employee in the previous example (entitled to 14 days annually) only worked for 6 months, they would receive:
14 days × (6 ÷ 12) = 7 days.
Why Calculate in Hours vs. Days?
While many contracts specify holidays in days, calculating in hours is often more accurate for employees who work irregular shift patterns or different numbers of hours on different days. Our calculator provides an estimated hourly equivalent based on a standard assumption of full-time daily hours.
If a part-time worker works 3 long days a week, giving them "days" off might result in them taking more paid hours off than they have accrued. In these cases, converting the total entitlement into an "holiday pot" of hours is the safest method for HR management.
Including Bank Holidays
In many jurisdictions (such as the UK), statutory leave entitlement includes public or bank holidays. When entering the "Full-Time Annual Holiday Entitlement" into the calculator, ensure you include bank holidays if they are part of the statutory minimum or the company contract.
For example, the UK statutory minimum is 5.6 weeks, which equates to 28 days for a full-time worker (often 20 days + 8 bank holidays). Part-time workers are entitled to a pro-rated portion of this total, regardless of whether they work on the actual days the bank holidays fall.