function calculateTimePay() {
// Get input values
var hoursInput = document.getElementById('trHours').value;
var minutesInput = document.getElementById('trMinutes').value;
var rateInput = document.getElementById('trRate').value;
// Parse values, defaulting to 0 if empty
var hours = parseFloat(hoursInput);
if (isNaN(hours)) hours = 0;
var minutes = parseFloat(minutesInput);
if (isNaN(minutes)) minutes = 0;
var rate = parseFloat(rateInput);
if (isNaN(rate)) rate = 0;
// Validation to prevent negative numbers
if (hours < 0 || minutes < 0 || rate < 0) {
alert("Please enter positive values for time and rate.");
return;
}
// Logic: Convert time to decimal hours
// Step 1: Divide minutes by 60
var decimalPart = minutes / 60;
// Step 2: Add integer hours
var totalDecimalHours = hours + decimalPart;
// Logic: Calculate Pay
var totalPay = totalDecimalHours * rate;
// Display Formatting
var displayTimeText = hours + "h " + minutes + "m";
var displayDecimalText = totalDecimalHours.toFixed(4) + " hrs";
var displayTotalText = "$" + totalPay.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Update DOM
document.getElementById('displayTime').innerHTML = displayTimeText;
document.getElementById('displayDecimal').innerHTML = displayDecimalText;
document.getElementById('displayTotal').innerHTML = displayTotalText;
// Show result box
document.getElementById('trResult').style.display = "block";
}
How to Multiply Hours and Minutes by an Hourly Rate
Calculating payroll or freelance earnings seems straightforward until you have to deal with minutes. While currency is calculated in a decimal system (Base 10), time is measured in a sexagesimal system (Base 60). This fundamental difference means you cannot simply multiply "8 hours and 30 minutes" by a dollar amount using a standard calculator without first converting the time.
If you enter "8.30" into a calculator to represent 8 hours and 30 minutes, your total pay calculation will be incorrect. In math, 0.30 represents 30/100 (30%), whereas 30 minutes represents 30/60 (50%) of an hour. This calculator automates the conversion process to ensure your billing is accurate.
The Conversion Formula
To accurately calculate pay based on hours and minutes, follow these steps:
Isolate the Minutes: Take the number of minutes worked.
Convert to Decimal: Divide the minutes by 60.
Add the Hours: Add the result to the number of whole hours worked.
Multiply by Rate: Multiply the total decimal hours by the hourly wage.
Real-World Example
Scenario: You worked 25 hours and 45 minutes at a rate of $40.00/hour.