How to Calculate Hours Worked, Step by Step

The four-step method

• Write the start and finish times in 24-hour format. 8:45 am stays 08:45, and 5:15 pm becomes 17:15 (add 12 to any pm hour except 12 pm).
• Subtract the start from the finish. If the finish minutes are smaller than the start minutes, borrow an hour: 17:15 − 08:45 becomes 16:75 − 08:45 = 8 hours 30 minutes.
• Take away unpaid breaks. With a 30-minute unpaid lunch, 8 h 30 min becomes 8 h 0 min.
• Convert to decimal hours if your timesheet or payroll needs it: divide the minutes by 60. 7 h 45 min is 7.75 hours.

That is the whole method. The rest of this guide covers the cases that trip people up, and the hours calculator does every step for you if you would rather not do it by hand.

A worked weekly timesheet

Add the hours and minutes columns separately, then carry every 60 minutes into an hour: 8 + 7 + 7 + 8 + 6 = 36 hours, and 0 + 55 + 45 + 20 + 20 = 140 minutes, which is 2 hours 20 minutes. The week is 38 hours 20 minutes, or 38.33 decimal hours. Adding the decimal column gives the same answer only if you keep at least two decimal places, which is why it is safer to total in hours and minutes and convert once at the end.

Overnight and night shifts

When a shift crosses midnight, the finish time looks smaller than the start. The fix is to add 24 hours to the finish time before subtracting. A shift from 22:00 to 06:30 becomes 30:30 − 22:00 = 8 hours 30 minutes.

In a spreadsheet the same idea is written as =MOD(finish − start, 1) * 24, which returns decimal hours and works for both day and night shifts. For day shifts only, =(finish − start) * 24 is enough. Format the cells as times, and subtract breaks as a time value such as 0:30.

Paid and unpaid breaks

Only unpaid breaks come off the total. In the US, federal rules treat short rest breaks of about 5 to 20 minutes as paid working time, while a genuine meal break of 30 minutes or more, where you are fully relieved of duty, can be unpaid. State law and your contract can add to this, so check what your employer counts.

If you clock out and back in for lunch, you can simply add up the two separate blocks instead of subtracting a break: 08:00 to 12:00 is 4 hours, 12:45 to 17:00 is 4 hours 15 minutes, and the day is 8 hours 15 minutes.

Rounding to the quarter hour

Many employers round punch times to the nearest quarter hour. The usual US practice, sometimes called the 7-minute rule, rounds 1 to 7 minutes down and 8 to 14 minutes up. A clock-in at 8:07 counts as 8:00, while 8:08 counts as 8:15. Rounding is allowed only if it is neutral over time and does not consistently favour the employer.

For your own records, keep the exact times. You can always round later, but you cannot un-round.

Minutes to decimal: the conversion you need most

A common mistake is to write 7 hours 30 minutes as 7.30. It is 7.5. Paying 7.30 hours underpays by 12 minutes. The decimal hours converter converts both ways, and the time duration calculator gives the gap between any two times or dates.

Converting 12-hour times without mistakes

Most errors in hours-worked sums come from mixing am and pm. Converting to 24-hour time first removes the problem:

• 12:00 am (midnight) is 00:00, and 12:30 am is 00:30.
• 1:00 am to 11:59 am stay the same: 7:15 am is 07:15.
• 12:00 pm (noon) stays 12:00, and 12:45 pm is 12:45.
• 1:00 pm to 11:59 pm add 12: 3:20 pm is 15:20, 11:00 pm is 23:00.

The military time converter has a full chart if you need to check a time quickly. Once both times are in 24-hour format, subtraction is just hours minus hours and minutes minus minutes, borrowing 60 minutes when needed.

Split shifts and multiple jobs

For split shifts, calculate each block separately and add them. A restaurant shift from 10:30 to 14:30 and again from 17:00 to 21:15 is 4 hours plus 4 hours 15 minutes, which is 8 hours 15 minutes. The gap in the middle is not work time unless your contract says otherwise.

If you track hours for several jobs or clients, keep a separate column for each one and total them at the end of the week. When you need to add many durations together, such as 3:45 + 2:30 + 1:50, the add and subtract time tool carries the minutes for you: that example comes to 8 hours 5 minutes.

For a single total between two dates and times, for example a long on-call period from Friday 18:00 to Monday 07:30, use the time duration calculator. That one is 61 hours 30 minutes.

From hours to pay

Multiply decimal hours by the hourly rate: 38.33 hours at $22 an hour is $843.26. If you work more than 40 hours in a week in the US, non-exempt employees must be paid at least 1.5 times their rate for the extra hours, so 44 hours at $22 is 40 × 22 + 4 × 33 = $1,012. To see how a week scales up to a year, read how many work hours are in a year.

Frequently asked questions

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