How to calculate hours worked (with lunch breaks)
Every pay period somebody has to turn a stack of clock-in and clock-out times into one number per person. Here is the method that holds up, including the parts that usually go wrong: lunch, midnight, and minutes.
Step 1: use a 24-hour clock
Subtracting 8:15 AM from 4:45 PM in your head is where mistakes start. Convert PM times by adding 12 to the hour: 4:45 PM becomes 16:45. Midnight is 0:00 and noon stays 12:00.
Step 2: subtract time in from time out
Subtract hours from hours and minutes from minutes. 16:45 minus 8:15 is 8 hours 30 minutes. When the minutes come out negative, borrow an hour: 16:10 minus 8:40 is 15:70 minus 8:40, which is 7 hours 30 minutes.
Step 3: take out the unpaid break
If the person took a 30 minute unpaid lunch, 8 hours 30 minutes becomes 8 hours. Short rest breaks are usually paid time under federal rules, so they normally stay in. If your team clocks out for lunch and back in, you have two shorter shifts instead, and nothing to subtract.
Step 4: handle shifts that cross midnight
A shift from 22:00 to 6:00 gives a negative answer (6 minus 22). Add 24 hours: the shift is 8 hours. Count it on the day it started so it doesn’t get split across two days on the timesheet.
Step 5: convert minutes to decimal hours
Payroll wants 7.50, not 7:30. Divide the minutes by 60: 30 minutes is 0.50, 20 minutes is 0.33, 45 minutes is 0.75. Our minutes to decimal chart has every minute from 1 to 60.
A full worked week
| Day | In | Out | Lunch | Hours |
|---|---|---|---|---|
| Mon | 8:00 | 16:30 | 30 min | 8:00 = 8.00 |
| Tue | 7:50 | 16:35 | 30 min | 8:15 = 8.25 |
| Wed | 8:05 | 12:00 | none | 3:55 = 3.92 |
| Thu | 8:00 | 17:10 | 30 min | 8:40 = 8.67 |
| Fri | 8:00 | 16:30 | 30 min | 8:00 = 8.00 |
Add the hours and minutes first (36 hours 50 minutes), then convert once: 36.83 hours. Converting each day and adding the decimals can drift by a hundredth or two because of rounding, which is why it’s cleaner to total minutes first.
Rounding
Some employers round punches to the nearest 5, 6 or 15 minutes. Federal rules allow rounding only if it evens out over time and doesn’t always favor the employer. The simplest choice is not to round at all and pay the actual minutes.
Want it done for you? The free time card calculator follows exactly these steps.
ClockInSheet puts the time clock on your team's phones and adds up the week for payroll. Free for up to 5 people.