How to Calculate Hours Worked (With Lunch Breaks) for Payroll
To calculate hours worked, subtract your start time from your end time, take out unpaid breaks, then convert the minutes to a decimal. Here's how to do it step by step, with a free calculator and real examples.
Updated October 30, 2026 · 6 min read
Hours worked calculator
Shifts that end after midnight are handled automatically. To add up a whole week, use the Add Up Hours tool.
Step 1: Write down start and end times
Use the exact clock-in and clock-out times from your time card, app or notes. If your employer rounds punches (for example to the nearest 15 minutes), round them first. More on that below.
Step 2: Convert to 24-hour time
Subtraction is much easier in 24-hour (military) time. Morning times stay the same. For afternoon and evening times, add 12 to the hour.
| 12-hour | 24-hour | 12-hour | 24-hour |
|---|---|---|---|
| 8:30 AM | 08:30 | 1:00 PM | 13:00 |
| 11:45 AM | 11:45 | 5:15 PM | 17:15 |
| 12:00 PM (noon) | 12:00 | 11:00 PM | 23:00 |
Step 3: Subtract start time from end time
Subtract hours from hours and minutes from minutes. If the end minutes are smaller than the start minutes, borrow 1 hour (60 minutes).
Step 4: Subtract unpaid breaks
Take out any unpaid meal break. In the example, a 30-minute unpaid lunch leaves 8 hours 15 minutes.
Which breaks are unpaid? Under federal rules, short rest breaks (usually 5 to 20 minutes) count as work time and must be paid. Meal breaks of 30 minutes or more can be unpaid if you are fully relieved of duty. Some states have their own break laws, so check yours.
Step 5: Convert minutes to decimal hours
Payroll needs decimal hours, so divide the minutes by 60. 15 ÷ 60 = 0.25, so 8 hours 15 minutes = 8.25 hours. You can use the time to decimal calculator or the minutes to decimal chart for this step.
Step 6: Multiply by your hourly rate
At $19.50 an hour, 8.25 × $19.50 = $160.88 for the day before taxes.
Don't multiply 8.15 by your rate. That treats 15 minutes as 0.15 of an hour (9 minutes) and underpays you.
Full week example
| Day | In | Out | Unpaid break | Worked | Decimal |
|---|---|---|---|---|---|
| Mon | 8:30 AM | 5:15 PM | 30 min | 8:15 | 8.25 |
| Tue | 8:00 AM | 4:40 PM | 30 min | 8:10 | 8.17 |
| Wed | 9:00 AM | 6:00 PM | 60 min | 8:00 | 8.00 |
| Thu | 8:15 AM | 5:00 PM | 30 min | 8:15 | 8.25 |
| Fri | 8:00 AM | 3:50 PM | 30 min | 7:20 | 7.33 |
| Total | 40:00 | 40.00 | |||
Add the minutes first (15 + 10 + 0 + 15 + 20 = 60 minutes = 1 hour), then the hours (8 + 8 + 8 + 8 + 7 = 39), for a total of exactly 40 hours.
What about overnight shifts?
If you start at 10:00 PM and finish at 6:30 AM, add 24 hours to the end time before subtracting: (6:30 + 24:00) − 22:00 = 30:30 − 22:00 = 8 hours 30 minutes. The calculator above does this for you.
Rounding rules employers use
Many US employers round clock punches to the nearest 15 minutes (the "7-minute rule") or the nearest 6 minutes. Federal rules generally allow this only if, over time, it averages out and doesn't consistently shortchange employees. See our guide to the 7-minute rule and time rounding for charts and examples.
When does overtime start?
Under the federal Fair Labor Standards Act, non-exempt employees earn overtime at 1.5 times their regular rate for hours over 40 in a workweek. A few states add daily overtime. California, for example, generally requires overtime after 8 hours in a day. Your total weekly hours from this method tell you whether overtime applies.
Frequently asked questions
How do I calculate hours worked in a day?
Subtract the start time from the end time, subtract any unpaid break, and convert the leftover minutes to a decimal by dividing by 60. 8:30 AM to 5:15 PM with a 30-minute lunch is 8.25 hours.
Is a 30-minute lunch break paid?
Not usually. Under federal rules, a meal break of 30 minutes or more can be unpaid if you are completely relieved of duty. Short rest breaks of about 5 to 20 minutes must be paid.
How many hours is 8 AM to 4:30 PM?
8 AM to 4:30 PM is 8 hours 30 minutes, or 8.5 hours. With a 30-minute unpaid lunch it is 8 hours.
How many hours is 9 AM to 5 PM?
9 AM to 5 PM is 8 hours. With a 30-minute unpaid lunch it is 7.5 hours.
How do I calculate hours worked if I work past midnight?
Add 24 hours to the end time, then subtract the start time. 10 PM to 6:30 AM is 8.5 hours.
Related tools
This guide is general information, not legal or payroll advice. Wage and break laws vary by state and employer.