Counting hours worked gets tricky with a lunch break, a 7:50 start or a shift past midnight. Here is how to calculate hours worked by hand, step by step. To skip the math, the hours calculator does a full week for you.
The basic rule
Hours worked = end time minus start time, minus any unpaid break.
Take a plain day. You clock in at 9:00 AM and clock out at 5:30 PM. That is 8 hours and 30 minutes on the clock. You took a 30-minute unpaid lunch. Take it off and you worked 8 hours.
Step 1: Convert to 24-hour time
AM and PM trip people up, so switch to 24-hour time first. Add 12 to any PM hour except 12 PM.
- 9:00 AM stays 9:00
- 12:00 PM stays 12:00
- 5:30 PM becomes 17:30
- 11:45 PM becomes 23:45
Now 17:30 minus 9:00 is easy: 8 hours 30 minutes.
Step 2: Subtract the minutes, then the hours
When the end minutes are smaller than the start minutes, borrow an hour.
Say you start at 7:50 AM and finish at 4:20 PM (16:20). You cannot take 50 from 20, so borrow: 16:20 becomes 15:80. Now subtract.
- Minutes: 80 minus 50 = 30
- Hours: 15 minus 7 = 8
That is 8 hours 30 minutes on the clock.
Step 3: Take off the lunch break
Only unpaid breaks come off. If your lunch is unpaid, subtract it. If your employer pays you through lunch, leave it in.
From the example above, 8:30 minus a 30-minute lunch is 8:00. With a 45-minute lunch it is 7:45. With a one-hour lunch it is 7:30.
Short paid rest breaks of 5 to 20 minutes are normally paid under US federal rules and stay in your hours. A bona fide meal break of 30 minutes or more, where you are fully relieved of work, is usually unpaid. Your employer's policy says which is which.
Step 4: Add up the week
Do each day on its own, then total the days. Keep hours and minutes in separate columns.
| Day | In | Out | Break | Worked |
|---|---|---|---|---|
| Mon | 9:00 AM | 5:30 PM | 30 min | 8:00 |
| Tue | 8:45 AM | 5:15 PM | 30 min | 8:00 |
| Wed | 9:10 AM | 6:00 PM | 60 min | 7:50 |
| Thu | 9:00 AM | 5:00 PM | 30 min | 7:30 |
| Fri | 8:30 AM | 4:45 PM | 30 min | 7:45 |
Add the minutes: 0 + 0 + 50 + 30 + 45 = 125 minutes. That is 2 hours 5 minutes. Add the hours: 8 + 8 + 7 + 7 + 7 = 37, plus the 2 from the minutes, is 39. The week is 39 hours 5 minutes.
Step 5: Turn it into decimal hours
Payroll systems want decimals, not minutes. 39 hours 5 minutes is not 39.05. Divide the minutes by 60: 5 ÷ 60 = 0.08. The week is 39.08 hours.
Worth memorizing: 15 minutes is 0.25, 30 minutes is 0.50, 45 minutes is 0.75. For anything else, the hours to decimal converter has a full minutes chart.
Overnight shifts
If you clock out after midnight, the end time looks smaller than the start time. Add 24 hours to the end time before you subtract.
Start 10:00 PM (22:00), end 6:00 AM. Make 6:00 into 30:00. Then 30:00 minus 22:00 is 8 hours.
Three mistakes to watch for
Treating minutes like decimals. 7:45 written as 7.45 shorts you 18 minutes a day. Always divide minutes by 60.
Taking off a paid break. If your lunch is paid, it stays in your hours. Check your pay stub or ask.
Rounding each day too early. Add the exact minutes first, then round the weekly total if your employer rounds. Rounding every day in the same direction adds up.
Once you have the hours
Multiply your decimal hours by your hourly rate to get gross pay. 39.08 hours at $18 is $703.44. Payroll that pays exact minutes gives $703.50; rounding to 39.08 first costs 6 cents. If your week goes over 40 hours, the extra hours are paid at time and a half under federal law. The overtime calculator splits regular from overtime pay for you.