How to calculate work hours and unpaid breaks
Turn clock-in and clock-out times into paid hours, subtract unpaid breaks, convert to decimal hours and handle shifts that cross midnight.
From clock times to worked hours
A shift starts as two clock readings, and the raw span between them is simply the later time minus the earlier one. Convert each time to minutes since midnight, subtract, and you have the elapsed minutes before any break. A 09:00 start is 540 minutes and a 17:30 finish is 1050 minutes, so the gap is 510 minutes, or eight and a half hours. Working in minutes avoids the mistakes that creep in when people try to subtract hours and minutes columns in their head.
Subtracting the unpaid break
Most jurisdictions and employers treat meal breaks as unpaid, so those minutes come off the total before it becomes payable time. Take the 510 minute span above, remove a 30 minute lunch, and 480 paid minutes remain, which is a clean eight hours. Short rest breaks are often paid and should not be deducted, so only subtract time you are genuinely off the clock. If several unpaid breaks happened in one shift, add them up and deduct the single combined figure.
Decimal hours versus hours and minutes
Payroll systems almost always want decimal hours because wages are the hours multiplied by a rate, and 7h 45m has to become 7.75 before that multiplication works. The conversion divides the leftover minutes by 60, so 45 minutes is 0.75 of an hour and 50 minutes is about 0.83. Rounding to two decimal places keeps the figure tidy while staying accurate to well under a minute. Keeping the hours and minutes label alongside makes the number easy for a human to sanity check.
Shifts that cross midnight
A night shift breaks the simple later minus earlier rule because the finish time is a smaller number than the start. Clock in at 23:00 and out at 07:00 and a naive subtraction gives a negative span. The fix is to add a full day of 1440 minutes whenever the end is not after the start, which turns that shift into a correct eight hours. Getting this right matters for overnight staff whose hours would otherwise be badly undercounted on a timesheet.