function calculateHourlyRate() {
// Get Inputs
var salary = parseFloat(document.getElementById('salaryAmount').value);
var frequency = document.getElementById('payFrequency').value;
var hoursWeek = parseFloat(document.getElementById('hoursPerWeek').value);
var weeksYear = parseFloat(document.getElementById('weeksPerYear').value);
// Validation
if (isNaN(salary) || salary <= 0) {
alert("Please enter a valid salary amount.");
return;
}
if (isNaN(hoursWeek) || hoursWeek <= 0) {
alert("Please enter valid work hours per week.");
return;
}
if (isNaN(weeksYear) || weeksYear 52.2) {
alert("Please enter valid weeks per year (1-52).");
return;
}
var annualSalary = 0;
// Normalize to Annual Salary first
if (frequency === 'annual') {
annualSalary = salary;
} else if (frequency === 'monthly') {
annualSalary = salary * 12;
} else if (frequency === 'weekly') {
annualSalary = salary * weeksYear;
} else if (frequency === 'daily') {
// Assuming 5 days a week standard for daily calc if not specified,
// but strictly speaking daily * days_per_week * weeks_year
// For simplicity in this logic, we derive annual from daily * 5 * weeks
annualSalary = salary * 5 * weeksYear;
}
// Calculate Totals
var totalAnnualHours = hoursWeek * weeksYear;
var hourlyRate = annualSalary / totalAnnualHours;
// Calculate break downs
// Note: Daily rate implies a standard day. We assume a 5-day work week for the daily breakdown unless specified otherwise.
// A more accurate daily rate is Hourly * (HoursPerWeek / 5)
var dailyRate = hourlyRate * (hoursWeek / 5);
var weeklyRate = hourlyRate * hoursWeek;
var monthlyRate = annualSalary / 12;
// Formatting function
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// Display Results
document.getElementById('hourlyResult').innerText = formatter.format(hourlyRate);
document.getElementById('dailyResult').innerText = formatter.format(dailyRate);
document.getElementById('weeklyResult').innerText = formatter.format(weeklyRate);
document.getElementById('monthlyResult').innerText = formatter.format(monthlyRate);
document.getElementById('annualResult').innerText = formatter.format(annualSalary);
// Show the results container
document.getElementById('results').style.display = 'block';
}
Understanding Pro Rata Hourly Rates
Calculating your pro rata hourly rate is essential for freelancers, part-time employees, and contractors who need to convert a fixed salary into an hourly figure. "Pro rata" implies "in proportion," meaning this calculation helps you understand the proportional value of your time based on standard working hours.
Whether you are negotiating a new contract, reducing your hours from full-time to part-time, or simply curious about your true earnings per hour, this calculator breaks down the math precisely.
How the Calculation Works
To determine your hourly rate from a salary, we use the following standard formula logic:
Step 1: Determine Annual Salary. If you input a monthly or weekly figure, it is annualized first (e.g., Monthly Salary × 12).
Step 2: Calculate Total Annual Hours. This is derived by multiplying your Standard Work Hours Per Week by the Weeks Worked Per Year. The standard is often 40 hours × 52 weeks = 2,080 hours.
Step 3: Divide. The Annual Salary is divided by Total Annual Hours to result in your gross Hourly Rate.
Why Adjust for Weeks Worked?
Most simple calculators assume a 52-week year. However, contractors often only bill for 48 or 46 weeks a year to account for unpaid holidays and sick leave. By adjusting the "Weeks Worked Per Year" input in this calculator, you get a more realistic "billable" hourly rate required to match a target annual income.
Scenario B: Part-Time Adjustment
If you move to a 3-day work week (24 hours), your hourly rate remains the same, but your pro-rata salary adjusts. This calculator helps you confirm that the hourly rate offered for the part-time role matches your full-time equivalent.
Disclaimer: This tool is for informational purposes only. It calculates gross figures and does not account for taxes, superannuation, insurance, or other payroll deductions. Always consult a financial professional for official payroll advice.