*Calculations are estimates based on the tax percentage provided. Actual payroll taxes may vary by jurisdiction and specific tax brackets.
function calculateProRata() {
// Get input values
var salaryStr = document.getElementById('pr_salary').value;
var basis = document.getElementById('pr_basis').value;
var totalDaysStr = document.getElementById('pr_total_days').value;
var workedDaysStr = document.getElementById('pr_worked_days').value;
var taxStr = document.getElementById('pr_tax').value;
// Parse values
var salary = parseFloat(salaryStr);
var totalDays = parseFloat(totalDaysStr);
var workedDays = parseFloat(workedDaysStr);
var taxRate = parseFloat(taxStr);
// Basic Validation
if (isNaN(salary) || isNaN(totalDays) || isNaN(workedDays)) {
alert("Please enter valid numbers for salary and working days.");
return;
}
if (totalDays totalDays) {
alert("Days actually worked cannot exceed total work days in the period.");
return;
}
// Default tax to 0 if empty
if (isNaN(taxRate)) {
taxRate = 0;
}
// Determine Monthly Base Salary
var monthlyBase = 0;
if (basis === 'annual') {
monthlyBase = salary / 12;
} else {
monthlyBase = salary;
}
// Calculate Daily Rate based on the specific month's total working days
var dailyRate = monthlyBase / totalDays;
// Calculate Gross Pro Rata Pay
var grossProRata = dailyRate * workedDays;
// Calculate Deductions
var deductions = grossProRata * (taxRate / 100);
// Calculate Net Pay
var netPay = grossProRata – deductions;
// Display Results
document.getElementById('res_daily_rate').innerHTML = formatCurrency(dailyRate);
document.getElementById('res_gross_pay').innerHTML = formatCurrency(grossProRata);
document.getElementById('res_deductions').innerHTML = "-" + formatCurrency(deductions);
document.getElementById('res_net_pay').innerHTML = formatCurrency(netPay);
// Show result box
document.getElementById('pr_result_box').style.display = 'block';
}
function formatCurrency(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
Understanding Pro Rata Pay
"Pro rata" is a Latin term meaning "in proportion." In the context of payroll, a pro rata salary calculation is used when an employee does not work a full pay period. This most commonly occurs when a new employee starts a job in the middle of a month, leaves a job before the month ends, or takes unpaid leave during a standard pay cycle.
Instead of receiving the full standard monthly salary, the employee receives a paycheck proportional to the days they actually worked. This calculator helps you estimate that proportional amount and your resulting take-home pay after taxes.
How is Pro Rata Salary Calculated?
The calculation generally follows a simple logical flow, though specific company policies regarding "total working days" can vary slightly. The standard formula used by this calculator is:
Determine Monthly Gross: If you are on an annual salary, divide by 12.
Determine Daily Rate: Divide the Monthly Gross by the total number of workdays available in that specific month (usually between 20 and 23 days excluding weekends).
Calculate Gross Pro Rata: Multiply the Daily Rate by the number of days you actually worked.
Estimate Net Pay: Deduct your estimated tax and benefit percentage to find the "take home" amount.
Example Calculation
Let's say you have an annual salary of $60,000. You started a new job on the 15th of a month that has 22 total working days. Since you started mid-month, you only worked 12 days.
Monthly Base: $60,000 / 12 = $5,000
Daily Rate: $5,000 / 22 = $227.27 per day
Gross Pro Rata Pay: $227.27 x 12 = $2,727.27
If your estimated tax rate is 25%, your take home pay would be approximately $2,045.45.
Why "Total Work Days" Matters
Not all months are created equal. February might only have 20 working days, while August might have 23. This means your "daily rate" effectively fluctuates slightly from month to month if you are a salaried employee. When calculating pro rata pay, it is crucial to use the correct number of working days for the specific month in question to ensure accuracy.
Factors Affecting Your Take Home Pay
While the gross pro rata calculation is mathematical, your net take-home pay depends on several deductions:
Income Tax: Federal and state/provincial taxes based on your bracket.
Social Security/Medicare: Mandatory government contributions.
Benefits: Health insurance, retirement contributions (401k), or union dues.
Use the "Estimated Tax & Deductions" field in the calculator to account for these combined costs.