The total annual salary if you worked full-time all year round.
The standard working week for a full-time employee.
The number of hours you are contracted to work per week.
Standard term time is often 38, 39, or 40 weeks.
Weeks of holiday pay you receive (often added to worked weeks).
Your Actual Annual Salary:0.00
Gross Monthly Pay:0.00
Gross Weekly Pay:0.00
Total Paid Weeks:0.00
FTE Ratio:0.00%
function calculateProRataSalary() {
// 1. Get input values using var
var fteSalary = document.getElementById('fteSalary').value;
var stdHours = document.getElementById('stdHours').value;
var actualHours = document.getElementById('actualHours').value;
var weeksWorked = document.getElementById('weeksWorked').value;
var holidayWeeks = document.getElementById('holidayWeeks').value;
// 2. Validate inputs
if (fteSalary === "" || stdHours === "" || actualHours === "" || weeksWorked === "" || holidayWeeks === "") {
alert("Please fill in all fields to calculate the salary.");
return;
}
// Convert strings to floats
fteSalary = parseFloat(fteSalary);
stdHours = parseFloat(stdHours);
actualHours = parseFloat(actualHours);
weeksWorked = parseFloat(weeksWorked);
holidayWeeks = parseFloat(holidayWeeks);
if (stdHours <= 0 || weeksWorked <= 0) {
alert("Standard hours and weeks worked must be greater than zero.");
return;
}
// 3. Define Constants for Calculation
// Using 52.1428 weeks per year (365 / 7) is standard for precise payroll calculations
var weeksInYear = 52.1428;
// 4. Calculate Logic
// Step A: Calculate the Hours Fraction (Part-time factor)
// Formula: Actual Hours / Standard Full-time Hours
var hoursFraction = actualHours / stdHours;
// Step B: Calculate the Weeks Fraction (Term-time factor)
// First, determine Total Paid Weeks (Weeks worked + Holiday weeks)
var totalPaidWeeks = weeksWorked + holidayWeeks;
// Formula: Total Paid Weeks / Weeks in Year (52.1428)
var weeksFraction = totalPaidWeeks / weeksInYear;
// Step C: Calculate Final Pro Rata Salary
// Formula: FTE Salary * Hours Fraction * Weeks Fraction
var annualProRata = fteSalary * hoursFraction * weeksFraction;
// Calculate derived values
var monthlyPay = annualProRata / 12;
var weeklyPay = annualProRata / 52.1428;
var fteRatio = (annualProRata / fteSalary) * 100;
// 5. Output Results
// Formatting numbers to currency or fixed decimals
// We assume generic currency based on input logic, but here we format as standard numbers with 2 decimals
var formatter = new Intl.NumberFormat('en-US', {
style: 'decimal',
minimumFractionDigits: 2,
maximumFractionDigits: 2
});
document.getElementById('displayAnnual').innerText = formatter.format(annualProRata);
document.getElementById('displayMonthly').innerText = formatter.format(monthlyPay);
document.getElementById('displayWeekly').innerText = formatter.format(weeklyPay);
document.getElementById('displayPaidWeeks').innerText = totalPaidWeeks.toFixed(2);
document.getElementById('displayRatio').innerText = fteRatio.toFixed(2) + "%";
// Show result box
document.getElementById('prResult').style.display = "block";
}
Understanding Pro Rata Term Time Calculations
For many professionals working in education, administration, or support roles, employment contracts are often based on "Term Time Only" (TTO) hours. This means you are employed for the weeks that the school or institution is open, rather than the full 52 weeks of the year. The Pro Rata Term Time Calculator above helps you accurately determine your actual take-home salary based on your specific working conditions compared to a Full-Time Equivalent (FTE) role.
What does "Pro Rata" mean?
"Pro Rata" is Latin for "in proportion." In the context of salary, it means calculating a proportionate salary for someone who works fewer hours or fewer weeks than a standard full-time employee. If a job advertises a salary of 30,000 FTE but states "Pro Rata," you will receive a percentage of that 30,000 based on exactly how much you work.
How is Term Time Salary Calculated?
The calculation typically involves two main reduction factors: your weekly hours and your working weeks per year.
Hours Factor: This compares your weekly hours to the standard working week (usually 37, 37.5, or 40 hours).
Weeks Factor: This compares your paid weeks (working weeks + holiday) to the full calendar year (52.143 weeks).
The standard formula used by most payroll departments is:
FTE Annual Salary: The salary you would earn if you worked full-time (usually 37+ hours) for the full year (52 weeks). This is often the figure seen on job advertisements.
Weeks Worked per Year: For school staff, this is typically between 38 and 40 weeks.
Paid Holiday Weeks: Even if you only work during term time, you are legally entitled to paid holidays. This is usually between 4 and 6 weeks, depending on your length of service and contract. Your Total Paid Weeks is the sum of weeks worked and holiday weeks.
52.143 Weeks: To be precise, payroll calculations use 365 days ÷ 7 days = 52.1428 weeks, rather than a flat 52. This ensures accuracy over leap years.
Example Calculation
Consider a Teaching Assistant role with the following details:
FTE Salary: 24,000
Standard Hours: 37 hours/week
Actual Hours: 30 hours/week
Weeks Worked: 39 weeks
Holiday Entitlement: 5 weeks
First, we calculate the Total Paid Weeks: 39 + 5 = 44 weeks.
Next, we find the Hours Fraction: 30 ÷ 37 = 0.8108.
Then, the Weeks Fraction: 44 ÷ 52.143 = 0.8438.
Finally, the salary: 24,000 × 0.8108 × 0.8438 ≈ 16,419 per year.
Use the calculator above to run these numbers for your specific contract to ensure you know exactly what your gross earnings should be.