How to Calculate Hours Worked for Your Timesheet
Calculate hours worked from clock-in to clock-out, subtract breaks, convert minutes to decimal hours, handle overnight shifts and weekly overtime.
Whether you fill out a timesheet, invoice clients by the hour or check your paycheck, you need to turn clock times into hours you can multiply by a rate. Times don't add like normal numbers, because an hour has 60 minutes, not 100. Here is how to do it right every time.
Step 1: subtract clock-in from clock-out
Convert both times to a 24-hour clock first. 5:15 PM is 17:15.
Example: 8:45 AM to 5:15 PM.
- From 8:45 to 16:45 is 8 hours.
- From 16:45 to 17:15 is 30 minutes.
- Total: 8 hours 30 minutes.
Step 2: subtract unpaid breaks
With a 30-minute unpaid lunch, 8 h 30 min − 30 min = 8 hours worked. Short breaks of about 5 to 20 minutes are generally counted as paid work time under U.S. federal rules; longer meal breaks, when you are fully relieved of duty, usually are not.
Step 3: convert minutes to decimal hours
Payroll and invoices use decimal hours. Divide the minutes by 60:
| Minutes | Decimal hours |
|---|---|
| 5 | 0.08 |
| 10 | 0.17 |
| 15 | 0.25 |
| 20 | 0.33 |
| 30 | 0.50 |
| 45 | 0.75 |
| 50 | 0.83 |
So 7 hours 45 minutes is 7.75 hours, not 7.45. Writing 7.45 is the most common timesheet mistake, and it underpays you by 18 minutes.
Overnight shifts
If the shift crosses midnight, add 24 hours to the clock-out time before subtracting. 10:00 PM to 6:30 AM: (6:30 + 24:00) − 22:00 = 8.5 hours.
Weekly totals and overtime
Add up the decimal hours for each day. Under the U.S. Fair Labor Standards Act, non-exempt employees earn at least 1.5 times their regular rate for hours over 40 in a workweek. Some states, such as California, also have daily overtime rules.
| Day | Hours |
|---|---|
| Monday | 8.00 |
| Tuesday | 8.50 |
| Wednesday | 9.00 |
| Thursday | 8.25 |
| Friday | 9.75 |
| Total | 43.50 |
At $22 an hour: 40 × $22 = $880 regular pay, plus 3.5 × $33 = $115.50 overtime, for $995.50 gross.
Rounding rules
Many employers round punches to the nearest 5, 6 or 15 minutes. Federal rules allow rounding only if, over time, it does not consistently shortchange employees. Keeping your own record of exact times is a good habit.
Spreadsheet formulas
| What you want | Formula (in A1, out B1, break in C1 as time) |
|---|---|
| Hours worked as time | =B1-A1-C1 |
| Decimal hours | =(B1-A1-C1)*24 |
| Overnight shift | =MOD(B1-A1,1)*24 |
The time duration calculator adds and subtracts hours and minutes for you, so you can total a week of shifts without converting by hand.
Frequently asked questions
How do I convert minutes to decimal hours?
Divide the minutes by 60. For example, 45 minutes is 45 ÷ 60 = 0.75 hours.
How many hours is 8:45 AM to 5:15 PM?
8.5 hours, or 8 hours if you take a 30-minute unpaid lunch.
How do I calculate hours for an overnight shift?
Add 24 hours to the end time before subtracting. 10 PM to 6:30 AM is 8.5 hours.
When does overtime start?
Under the federal Fair Labor Standards Act, after 40 hours in a workweek for non-exempt employees, paid at least 1.5 times the regular rate. Some states add daily overtime rules.
Lawyer for almost 20 years, focused on digital law, and creator of CoringaWeb. He writes the guides and builds the tools on this site.
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