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How to calculate work hours and hours worked
Hours worked is the end time minus the start time, minus any unpaid break. Do that for each day, then add the days up for the week. Keep minutes as minutes while you work: 7:45 on a time card is 7 hours 45 minutes, which payroll writes as 7.75, not 7.45.
Quick answer: Write both punches as minutes after midnight and take the start from the end. A shift that ends after midnight needs 1,440 minutes added to the end first. Subtract the unpaid break and divide by 60 for decimal hours. So 9:00 AM to 5:30 PM with a 30-minute unpaid lunch is 510 − 30 = 480 minutes, or 8.00 hours.
Key takeaways
- Work out each stretch of work on its own and add them up; a split shift is just two stretches.
- If the clock-out looks earlier than the clock-in, the shift went past midnight, so add 1,440 minutes to the clock-out.
- Decimal hours are minutes ÷ 60. A 7:45 day goes on payroll as 7.75.
- Federal rules pay short rest breaks of 5 to about 20 minutes. A real meal break, normally 30 minutes or more with no duties, can be unpaid.
- Federal overtime starts after 40 hours in the employer's fixed seven-day workweek, and some states add daily overtime.
The basic work hours formula
Every shift comes down to one line: work time = end time − start time − unpaid breaks. Run it once per shift, then add the shifts for the week.
The usual slip is with minutes. A clock counts in sixties, so 45 minutes is three quarters of an hour, not 45 hundredths. Turning each time into plain minutes before you subtract keeps you clear of that.
1. Convert each time to minutes past midnight
Multiply the hour by 60, then add the minutes. On a 24-hour clock, 9:00 AM is hour 9. That gives 9 × 60 = 540 minutes. 5:30 PM is hour 17, so it is 17 × 60 + 30 = 1,050 minutes.
Take care with noon and midnight on a 12-hour clock. 12:00 AM is midnight, which is 0 minutes. 12:00 PM is noon, which is 720 minutes.
2. Subtract the start time from the end time
For a shift that starts and ends on the same day, take the start minutes from the end minutes. For 9:00 AM to 5:30 PM, that is 1,050 − 540 = 510 minutes. Divide 510 by 60 and you get 8 hours 30 minutes.
A night shift breaks this, because the clock-out number comes out smaller than the clock-in. The fix is to add 1,440 minutes, one whole day, to the clock-out before you subtract.
Overnight example: 10:00 PM to 6:00 AM
10:00 PM is 1,320 minutes and 6:00 AM is 360. Since 360 is the smaller number, it becomes 360 + 1,440 = 1,800, and 1,800 − 1,320 leaves 480 minutes, exactly 8 hours.
Identical start and end times normally mean 0 hours. Treat it as 24 hours only for a real full-day shift, like a 24-hour on-call at a fire station.
3. Subtract unpaid breaks
Now take the unpaid break off. An 8:30 shift with a 30-minute unpaid lunch leaves 8 hours of work.
Only subtract breaks that are really unpaid. Federal rules count short rest breaks of 5 to about 20 minutes as work time; a meal break can be unpaid when you're completely relieved of duty, and it's usually 30 minutes or more. Your state and your employer may add rules of their own.
4. Calculate split shifts separately
Some people work two separate blocks in one day. Work out each block by itself, then add them up. A morning block from 9:00 AM to 1:00 PM is 4 hours. An evening block from 3:00 PM to 7:00 PM is another 4 hours. Together they make 8 hours for the day.
The time card calculator lets you enter more than one block for each day. It also keeps regular hours and overtime apart.
5. Add the week
Once each day has its own total, the week is simple addition. Five 8-hour days make 40 hours. One extra 4-hour shift on Saturday brings the week to 44 hours.
Those extra 4 hours are where overtime comes in. Under federal law, most hourly workers who are not exempt get overtime after 40 hours in a workweek. The workweek is a fixed run of seven days that the employer sets. It does not have to start on a Monday. Some jobs are exempt from overtime. A few states, such as California, also pay overtime after 8 hours in one day.
So use the overtime number as a guide. ClockTotals does the sums for you. Your employer's policy and your state's law decide what you are actually paid.
6. Convert work time to decimal hours
Most payroll systems want hours as a decimal, and the conversion is minutes ÷ 60. The quarter hours are worth learning by heart:
| Hours and minutes | Decimal hours |
|---|---|
| 8 hours 0 minutes | 8.00 |
| 7 hours 15 minutes | 7.25 |
| 7 hours 30 minutes | 7.50 |
| 7 hours 45 minutes | 7.75 |
| 8 hours 15 minutes | 8.25 |
Typing 7.45 for a 7:45 day is an easy mistake to make, and it costs money: 7.45 decimal hours is only 7 hours 27 minutes, so 18 minutes go missing.
Worked weekly example
Take a Monday-to-Friday job from 9:00 AM to 5:30 PM with a 30-minute unpaid lunch. Each day spans 8 hours 30 minutes on the clock, and 8:00 once lunch comes off.
Five of those days give 40 hours. Cover a 4-hour Saturday shift for a coworker and the week reaches 44.
If you're a nonexempt hourly worker in the US and your workweek runs Monday to Sunday, every one of those Saturday hours lands past 40, so federal law makes them overtime. Exempt staff and other countries work under different rules.
Worked example: overnight shift with a break
A night shift starts at 10:15 PM and ends at 6:50 AM the next morning. There is a 30-minute unpaid meal break. Here is the time worked in hours and minutes, and as a decimal.
- Change both times to minutes past midnight. 10:15 PM is 22 × 60 + 15 = 1,335, and 6:50 AM is 6 × 60 + 50 = 410.
- The end (410) is smaller than the start (1,335), so the shift crossed midnight. Add a day: 410 + 1,440 = 1,850.
- Take away the start: 1,850 − 1,335 = 515 minutes, which is 8 hours 35 minutes.
- Take off the unpaid break: 515 − 30 = 485 minutes, which is 8 hours 5 minutes.
- Divide by 60 for decimal hours: 485 ÷ 60 = 8.083, or about 8.08. Typing 8.05 instead would cut 2 minutes from the pay.
Result: 8 hours 5 minutes of work time, or 8.08 decimal hours.
In Excel / Google Sheets
A spreadsheet stores a time as part of a day. Noon is 0.5, and 6:00 AM is 0.25. So an end time minus a start time gives a fraction of a day. Multiply that by 24 to turn it into hours. The formulas below work the same way in Excel and in Google Sheets.
Put the start time in A2 and the end time in B2, typed as normal times such as 9:00 AM. For the lunch formulas, put the unpaid break in minutes in C2.
| What you want | Formula | Example |
|---|---|---|
| Hours between times, shown as a time | =B2-A2 | 9:00 AM to 5:30 PM shows 8:30 |
| Hours between times as decimal hours | =(B2-A2)*24 | 9:00 AM to 5:30 PM gives 8.5 |
| Decimal hours after an unpaid lunch | =(B2-A2)*24-C2/60 | Same shift, 30 in C2, gives 8 |
| Overnight shift, shown as a time | =MOD(B2-A2,1) | 10:00 PM to 6:00 AM shows 8:00 |
| Overnight shift as decimal hours | =MOD(B2-A2,1)*24 | 10:00 PM to 6:00 AM gives 8 |
| Overnight shift after an unpaid lunch | =MOD(B2-A2,1)*24-C2/60 | 10:15 PM to 6:50 AM, 30 in C2, gives 8.08 |
| A time such as 7:45 in E2 as decimal hours | =E2*24 | 7:45 gives 7.75 |
| Weekly total of decimal hours in D2 to D8 | =SUM(D2:D8) | Five days of 8 give 40 |
The MOD formula is what makes night shifts work. A plain B2-A2 turns negative when the shift ends after midnight. MOD(B2-A2,1) adds one day in that case and leaves a normal day shift alone.
Set the cells with decimal results to the Number format. Excel sometimes shows them as a clock time, so 8.5 can look like a strange time of day.
If you add up times instead of decimals, format the total as [h]:mm in Excel. The square brackets stop the clock from wrapping at 24. Without them, a 44-hour week shows as 20:00. In Google Sheets, choose Format, then Number, then Duration to get the same result.
Which ClockTotals calculator to use
The hours between times calculator is the quickest choice when you have one start time and one end time.
The work hours calculator suits a normal week, with a start, an end and a break for each day.
The time card calculator is built for a full time card. It takes more than one block a day and shows regular and overtime hours apart.
Work hours questions
How do I calculate hours worked in a day?
Take the start time away from the end time, then take off any unpaid breaks. Changing both times to minutes first stops mistakes with AM, PM and minutes.
How do I calculate hours for a shift that crosses midnight?
Add 1,440 minutes (a full day) to the clock-out before subtracting the clock-in. A 10:00 PM to 6:00 AM shift works out to 8 hours that way.
How do I convert minutes to decimal hours?
Divide them by 60. A quarter hour is 0.25, half an hour is 0.5 and 45 minutes is 0.75.
How do I calculate hours worked in Excel or Google Sheets?
With the clock-in in A2 and the clock-out in B2, =MOD(B2-A2,1)*24 returns decimal hours, and it copes with night shifts too.
Are lunch breaks counted as hours worked?
Federal rules let a real meal break go unpaid when it's normally 30 minutes or longer and you're fully off duty. Short rest breaks of about 5 to 20 minutes have to be paid. Your state or employer may go further.
How many hours is 9 to 5?
Eight hours on the clock. Take off a 30-minute unpaid lunch and 7.5 hours are left to pay.
When do hours count as overtime?
Under the Fair Labor Standards Act, covered nonexempt workers earn at least 1.5 times their regular rate once they pass 40 hours in a workweek. A handful of states, California among them, also count overtime by the day.
Sources
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