The standard hours a full-time employee works per week.
Standard annual leave allowance in weeks (e.g., 5.6 for UK statutory).
The specific number of hours you are contracted to work per week.
Enter 12 for a full year, or less if starting/leaving mid-year.
Please enter valid positive numbers in all fields.
Pro Rata Percentage (FTE):0%
Total Annual Entitlement:0 Hours
Accrual for Period Worked:0 Hours
function calculateLeave() {
var ftHoursInput = document.getElementById('ft_hours');
var leaveWeeksInput = document.getElementById('leave_weeks');
var myHoursInput = document.getElementById('my_hours');
var monthsInput = document.getElementById('months_worked');
var resultBox = document.getElementById('result_box');
var errorMsg = document.getElementById('error_msg');
var ftHours = parseFloat(ftHoursInput.value);
var leaveWeeks = parseFloat(leaveWeeksInput.value);
var myHours = parseFloat(myHoursInput.value);
var monthsWorked = parseFloat(monthsInput.value);
// Validation
if (isNaN(ftHours) || isNaN(leaveWeeks) || isNaN(myHours) || isNaN(monthsWorked) ||
ftHours <= 0 || leaveWeeks < 0 || myHours < 0 || monthsWorked 12) {
errorMsg.style.display = 'block';
resultBox.style.display = 'none';
return;
}
errorMsg.style.display = 'none';
// Calculation Logic
// 1. Calculate FTE Percentage (My Hours / FT Hours)
var fteRatio = myHours / ftHours;
var ftePercentage = fteRatio * 100;
// 2. Calculate Total Annual Entitlement in Hours
// Formula: Your Weekly Hours * Entitlement Weeks
// (Note: This is mathematically equivalent to FT Hours * Weeks * FTE Ratio)
var totalAnnualHours = myHours * leaveWeeks;
// 3. Calculate Accrued Hours based on duration worked
var accruedHours = totalAnnualHours * (monthsWorked / 12);
// Display Results
document.getElementById('res_percentage').innerHTML = ftePercentage.toFixed(2) + '%';
document.getElementById('res_total_hours').innerHTML = totalAnnualHours.toFixed(2) + ' Hours';
document.getElementById('res_accrued_hours').innerHTML = accruedHours.toFixed(2) + ' Hours';
resultBox.style.display = 'block';
}
Understanding Pro Rata Annual Leave in Hours
Calculating annual leave for part-time employees or those working irregular hours can be complex. Unlike full-time staff who might track holidays in days, it is often more accurate and fair to calculate pro rata annual leave in hours. This ensures that employees are compensated exactly for the time they would have been working, regardless of shift length.
How the Calculation Works
The "Pro Rata" (in proportion) calculation adjusts the standard full-time holiday entitlement to match the reduced hours of a part-time worker. The formula generally follows these steps:
Step 1: Determine Full-Time Entitlement. Identify the statutory or contractual leave weeks (e.g., 5.6 weeks in the UK).
Step 2: Apply to Weekly Hours. Multiply the number of hours the employee works per week by the entitlement weeks.
Step 3: Adjust for Tenure. If the employee has not worked a full year, divide by 12 and multiply by the months worked.
Realistic Example: Part-Time Worker
Scenario: Sarah works 22.5 hours per week. The company standard for full-time staff is 37.5 hours with 5.6 weeks of leave.
If Sarah wanted to take a week off where she was scheduled for 22.5 hours, she would use 22.5 hours of her 126-hour allowance.
Why Calculate in Hours Instead of Days?
Calculating leave in days works well for employees who work fixed standard days (e.g., 9 am to 5 pm, Monday to Friday). However, for shift workers or part-time staff working different hours on different days, a "day" is ambiguous.
For example, if an employee works 4 hours on Monday and 8 hours on Tuesday, taking a "day" of leave has a different value depending on which day is taken. By converting the entire entitlement pot into hours, the deduction is always accurate relative to the shift missed.
Partial Years (Starters and Leavers)
If an employee starts or leaves partway through the holiday year, their entitlement must be pro-rated further based on time served. Our calculator includes a "Duration of Employment" field to handle this automatically. The formula simply takes the full annual hour entitlement and multiplies it by the fraction of the year worked (e.g., 6/12 for six months).
Common Statutory Minimums
While contracts vary, most countries have a statutory minimum. For instance:
United Kingdom: 5.6 weeks (capped at 28 days for full-time).
Australia: Generally 4 weeks based on ordinary hours of work.
New Zealand: 4 weeks paid annual holidays.
Always check your specific employment contract, as employers often offer enhanced schemes above the statutory minimum.