function calculateTime() {
var start = document.getElementById('startTime').value;
var end = document.getElementById('endTime').value;
var breakMins = parseFloat(document.getElementById('breakTime').value) || 0;
var rate = parseFloat(document.getElementById('hourlyRate').value) || 0;
if (!start || !end) {
alert("Please enter both start and end times.");
return;
}
var startParts = start.split(':');
var endParts = end.split(':');
var startTotalMinutes = (parseInt(startParts[0]) * 60) + parseInt(startParts[1]);
var endTotalMinutes = (parseInt(endParts[0]) * 60) + parseInt(endParts[1]);
// Handle overnight shifts
if (endTotalMinutes < startTotalMinutes) {
endTotalMinutes += 1440; // Add 24 hours in minutes
}
var netMinutes = endTotalMinutes – startTotalMinutes – breakMins;
if (netMinutes 0) {
var totalPay = decimalHours * rate;
document.getElementById('totalPayDisplay').innerText = '$' + totalPay.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('payDisplayWrapper').style.display = 'block';
} else {
document.getElementById('payDisplayWrapper').style.display = 'none';
}
document.getElementById('resultArea').style.display = 'block';
}
Understanding Hours Worked Calculations
Calculating hours worked accurately is essential for both employees and employers to ensure fair compensation and compliance with labor laws. While it seems simple, variables like lunch breaks, overnight shifts, and decimal conversions can make manual tracking difficult.
How to Calculate Hours Worked Manually
To calculate your daily work hours, follow these steps:
Determine Start and End Time: Record the exact time you began work and the time you finished.
Convert to 24-Hour Format: This simplifies the math, especially if your shift crosses the noon or midnight threshold.
Subtract the Start Time from the End Time: This gives you the total elapsed time.
Subtract Unpaid Breaks: Deduct the duration of your lunch or rest breaks from the total.
Convert Minutes to Decimals: To multiply your hours by your hourly rate, you must convert minutes into a decimal format (e.g., 30 minutes = 0.5 hours).
The Importance of Decimal Hours
Payroll systems rarely use the "Hours:Minutes" format for calculations. Instead, they use decimal hours. To convert minutes to decimals, divide the number of minutes by 60. For example, if you worked 8 hours and 15 minutes:
Minutes
Decimal Equivalent
15 Minutes
0.25
30 Minutes
0.50
45 Minutes
0.75
Example Calculation
Let's say an employee clocks in at 8:30 AM and clocks out at 5:15 PM, with a 45-minute unpaid lunch break. Their hourly rate is $20.00.
Total span: 8:30 AM to 5:15 PM is 8 hours and 45 minutes.
If you start work at 10:00 PM and finish at 6:00 AM the next day, the calculation requires adding 24 hours to the end time to avoid negative results. Our calculator handles this automatically, ensuring that graveyard shifts are calculated with the same precision as standard daytime shifts.