Standard is 52. Enter less for term-time only (e.g., 39).
Calculation Results
Pro Rata Annual Salary:–
Gross Monthly Pay:–
Gross Weekly Pay:–
FTE (Full Time Equivalent):–
Effective Hourly Rate:–
function calculateProRataSalary() {
var ftSalaryInput = document.getElementById('ftSalary').value;
var ftHoursInput = document.getElementById('ftHours').value;
var ptHoursInput = document.getElementById('ptHours').value;
var weeksInput = document.getElementById('weeksPerYear').value;
// Basic Validation
if (ftSalaryInput === "" || ftHoursInput === "" || ptHoursInput === "" || weeksInput === "") {
alert("Please fill in all fields to calculate your pro rata salary.");
return;
}
var ftSalary = parseFloat(ftSalaryInput);
var ftHours = parseFloat(ftHoursInput);
var ptHours = parseFloat(ptHoursInput);
var weeksWorked = parseFloat(weeksInput);
if (ftHours <= 0 || weeksWorked <= 0) {
alert("Hours and Weeks must be greater than zero.");
return;
}
// Calculation Logic
// 1. Calculate the Hours Ratio
var hoursRatio = ptHours / ftHours;
// 2. Calculate the Weeks Ratio (Standard year is 52 weeks)
var weeksRatio = weeksWorked / 52.0;
// 3. Total Pro Rata Factor
var totalFactor = hoursRatio * weeksRatio;
// 4. Calculate Salaries
var proRataAnnual = ftSalary * totalFactor;
var proRataMonthly = proRataAnnual / 12;
var proRataWeekly = proRataAnnual / 52;
// 5. Hourly Rate (Based on Full Time logic)
// Full Salary / 52 weeks / Full Time Hours
var hourlyRate = ftSalary / 52 / ftHours;
// Formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// Update DOM
document.getElementById('resAnnual').innerText = formatter.format(proRataAnnual);
document.getElementById('resMonthly').innerText = formatter.format(proRataMonthly);
document.getElementById('resWeekly').innerText = formatter.format(proRataWeekly);
document.getElementById('resHourly').innerText = formatter.format(hourlyRate);
// Display FTE as a decimal (e.g. 0.5 FTE)
document.getElementById('resFTE').innerText = totalFactor.toFixed(3) + " FTE";
document.getElementById('prResult').style.display = "block";
}
Understanding Pro Rata Pay
Pro rata is a Latin term meaning "in proportion." In the context of employment, a pro rata salary refers to the amount of pay quoted for a part-time employee, calculated as a proportion of what they would earn if they worked full-time.
This calculator helps you determine your actual take-home potential based on reduced hours or reduced weeks (such as term-time work for education professionals).
How is Pro Rata Calculated?
The calculation generally involves two main factors:
Hours Worked: Comparing your contracted part-time hours against the company's standard full-time week (typically 37.5 or 40 hours).
Weeks Worked: Adjusting for positions that do not cover the full 52 weeks of the year, such as teachers or school administrators who may only be paid for 39 or 44 weeks.
The Formula
The math behind the calculation is straightforward:
(Part-Time Hours ÷ Full-Time Hours) × (Weeks Worked ÷ 52) × Full-Time Salary = Pro Rata Salary
Example Scenario
Imagine a job advertises a salary of $40,000 per annum (Full-Time Equivalent).
Full-Time Hours: 40 hours/week
Your Hours: 20 hours/week
Weeks Worked: 52 weeks (Standard)
In this case, you work exactly half the standard hours. Therefore: (20 ÷ 40) × $40,000 = $20,000 per year.
Term-Time Only Adjustments
For educational roles, you often work fewer than 52 weeks. If you work 39 weeks a year at 40 hours a week (Full-time hours, but part-time weeks), the calculation includes the weeks ratio:
(39 ÷ 52) × $40,000 = $30,000 per year.
Why Use a Pro Rata Calculator?
Job listings often display the "FTE" (Full-Time Equivalent) salary to make the role look more attractive or to standardize pay grades. Using this calculator ensures you understand exactly what the gross pay will be before applying or signing a contract, avoiding surprises in your first paycheck.