If you just want the total, the work hours calculator takes start, end, and break times for each shift and gives hours, decimal hours, and pay. This guide shows the method behind it for a single day.
Step 1: Switch to 24-hour time
AM/PM is where most hand calculations go wrong. Add 12 to any PM hour except 12 PM itself: 5:45 PM becomes 17:45, while 9:15 AM stays 9:15.
Step 2: Subtract start from end
Subtract the start time from the end time. 17:45 − 9:15 is 8 hours 30 minutes. If the minutes come out negative, borrow an hour: 16:20 − 7:50 is 15:80 − 7:50, which is 8 hours 30 minutes.
Step 3: Take off unpaid breaks
Subtract only the breaks you aren't paid for. In the US, short rest breaks — roughly 5 to 20 minutes — generally count as paid work time under federal law. A genuine meal break, usually 30 minutes or more with no work expected, doesn't have to be paid. State rules and employment contracts can add to this, so check yours.
Example: 9:15 AM to 5:45 PM, 30-minute lunch
Hours worked: 8.00 hours
Step 4: Convert minutes to decimal hours
Payroll systems want decimal hours, so divide the leftover minutes by 60. 15 minutes is 0.25, 30 minutes is 0.5, and 45 minutes is 0.75. The decimal hours converter has every minute from 1 to 60.
Example: 7:50 AM to 4:20 PM, 45-minute lunch
In decimal: 7 + 45 ÷ 60 = 7.75 hours
Common mistakes
- Writing 7:45 as 7.45. 7 hours 45 minutes is 7.75 hours. At $20/hour, that slip underpays $6.
- Subtracting paid breaks. Only unpaid time comes off.
- Mixing AM and PM. Convert to 24-hour time before you subtract.
More than one day
To total a week for payroll, see how to total a weekly timesheet. For shifts that run past midnight, see how to calculate overnight shift hours. Or enter every shift in the work hours calculator, which handles breaks, overnight shifts, and pay together.