Please enter valid positive numbers for all fields.
Pro Rata Annual Salary
Monthly Gross Pay
Weekly Gross Pay
Hourly Rate
FTE Ratio
function calculateProRata() {
// Get input values using var
var ftSalaryInput = document.getElementById('fullTimeSalary');
var stdHoursInput = document.getElementById('standardHours');
var actHoursInput = document.getElementById('actualHours');
var weeksInput = document.getElementById('workWeeks');
var resultsDiv = document.getElementById('prpResults');
var errorDiv = document.getElementById('prpError');
// Parse values
var ftSalary = parseFloat(ftSalaryInput.value);
var stdHours = parseFloat(stdHoursInput.value);
var actHours = parseFloat(actHoursInput.value);
var weeks = parseFloat(weeksInput.value);
// Validation
if (isNaN(ftSalary) || isNaN(stdHours) || isNaN(actHours) || isNaN(weeks) ||
ftSalary < 0 || stdHours <= 0 || actHours < 0 || weeks <= 0) {
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
}
// Hide error if valid
errorDiv.style.display = 'none';
// Calculation Logic
// 1. Calculate Hourly Rate based on full time stats
var totalFtHoursPerYear = stdHours * weeks;
var hourlyRate = ftSalary / totalFtHoursPerYear;
// 2. Calculate Pro Rata totals
var proRataWeekly = hourlyRate * actHours;
var proRataAnnual = proRataWeekly * weeks;
var proRataMonthly = proRataAnnual / 12;
// 3. Calculate FTE (Full Time Equivalent) Ratio
var fteRatio = actHours / stdHours;
// Formatter for currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2,
maximumFractionDigits: 2
});
// Update DOM
document.getElementById('resAnnual').innerHTML = formatter.format(proRataAnnual);
document.getElementById('resMonthly').innerHTML = formatter.format(proRataMonthly);
document.getElementById('resWeekly').innerHTML = formatter.format(proRataWeekly);
document.getElementById('resHourly').innerHTML = formatter.format(hourlyRate);
document.getElementById('resRatio').innerHTML = fteRatio.toFixed(3) + " (FTE)";
// Show results
resultsDiv.style.display = 'block';
}
How to Calculate Pro Rata Pay
Calculating pro rata pay is essential for understanding your earnings when you work part-time hours, start a job part-way through a pay period, or change your working hours. The term "pro rata" is Latin for "in proportion," meaning your salary is calculated according to the proportion of a full-time role that you actually work.
What is Pro Rata Salary?
A pro rata salary is a scaled-down version of a full-time salary. Employers often advertise roles with a "Full-Time Equivalent" (FTE) salary, but if the role is part-time, you will only receive a percentage of that figure based on your contracted hours.
For example, if a job advertises $60,000 per year for a 40-hour week, but you only work 20 hours, your pro rata pay would be 50% of the total, or $30,000.
The Pro Rata Formula
To calculate your pro rata salary manually, you need to determine your "FTE Ratio." The standard formula used by HR departments and payroll software is:
(Annual Full-Time Salary / Standard Full-Time Hours) × Your Actual Hours = Pro Rata Salary
Broken down step-by-step:
Determine the Hourly Rate: Divide the full-time annual salary by the total annual full-time hours (usually 52 weeks × 40 hours = 2080 hours).
Calculate Weekly Pay: Multiply the hourly rate by your actual contracted weekly hours.
Calculate Annual Pro Rata: Multiply your weekly pay by the number of paid weeks in the year (typically 52).
Example Calculation
Let's say you are applying for a job with the following details:
Full-Time Salary: $52,000
Standard Hours: 40 hours/week
Your Hours: 24 hours/week (3 days)
First, find the hourly rate: $52,000 ÷ (40 × 52) = $25.00 per hour.
Next, apply your hours: $25.00 × 24 hours = $600.00 per week.
Finally, find the annual total: $600.00 × 52 weeks = $31,200 per year.
Does Pro Rata Apply to Bonuses and Benefits?
Generally, yes. Most monetary benefits, such as bonuses and holiday pay, are also calculated on a pro rata basis. If a company offers 20 days of vacation to full-time staff, a part-time employee working 50% of the standard hours would typically receive 10 days of vacation. However, some benefits like health insurance may be offered in full regardless of hours worked, depending on company policy and local labor laws.