Excel is a powerful tool for working with time values, such as hours, minutes, and seconds. You can use Excel to calculate the difference between two times, add or subtract time values, sum multiple times, and more. In this article, we will show you how to perform some common time calculations in Excel, and explain the basic theory behind them.
Before we start, we need to understand how Excel stores and displays time values. Excel treats time values as fractions of a day. For example, 12:00 PM is 0.5, because it is half a day. Similarly, 6:00 AM is 0.25, and 6:00 PM is 0.75. This means that you can use simple arithmetic operations to manipulate time values, such as adding, subtracting, multiplying, and dividing.
However, there are some caveats to keep in mind when working with time values in Excel. First, you need to format the cells that contain time values with a proper time format, such as h:mm:ss, otherwise Excel will display them as decimals. Second, you need to be careful when the result of a time calculation exceeds 24 hours, or is negative. Excel will not display these values correctly unless you apply a custom time format that allows for more than 24 hours, or shows negative time values.
Calculating Time Difference
One of the most common time calculations in Excel is finding the difference between two times, or the elapsed time. For example, you may want to know how long it takes for an employee to complete a task, or how much time you spent on a project.
To calculate the time difference between two times, you can simply subtract the start time from the end time, using the minus sign (-). For example, if the start time is in cell A2, and the end time is in cell B2, you can use this formula:
=B2-A2
This will give you the time difference in the default time format, such as 4:10:20. However, if you want to display the time difference in a different format, such as hours only, or minutes and seconds only, you need to apply a custom time format to the cell. To do this, follow these steps:
- Select the cell that contains the formula.
- On the Home tab, in the Number group, click the arrow next to the General box, and then click More Number Formats.
- In the Format Cells dialog box, click Custom in the Category list, and then type a custom time format in the Type box.
Here are some examples of custom time formats that you can use:
- h: Elapsed hours, display as 4.
- h:mm: Elapsed hours and minutes, display as 4:10.
- h:mm:ss: Elapsed hours, minutes, and seconds, display as 4:10:20.
- [h]: Elapsed hours that allow for more than 24 hours, display as 28.
- [mm]: Elapsed minutes that allow for more than 60 minutes, display as 250.
- [ss]: Elapsed seconds that allow for more than 60 seconds, display as 1500.
- -h:mm: Elapsed hours and minutes that show negative time values, display as -1:30.
Adding or Subtracting Time Values
Another common time calculation in Excel is adding or subtracting time values, such as adding hours, minutes, or seconds to a given time, or subtracting them from a given time. For example, you may want to know what time it will be after adding 3 hours and 15 minutes to the current time, or what time it was 2 hours and 30 minutes ago.
To add or subtract time values, you can use the plus sign (+) or the minus sign (-) as usual. For example, if the current time is in cell A2, and you want to add 3 hours and 15 minutes to it, you can use this formula:
=A2+TIME(3,15,0)
This will give you the result in the default time format, such as 3:45 PM. The TIME function is used to create a valid time value from the given hours, minutes, and seconds. You can also use the TIMEVALUE function to create a time value from a text string, such as “3:15 PM”. For example, you can use this formula:
=A2+TIMEVALUE("3:15 PM")
This will give you the same result as the previous formula. However, if you want to subtract 2 hours and 30 minutes from the current time, you need to use a different formula:
=A2-TIME(2,30,0)
This will give you the result in the default time format, such as 10:00 AM. However, if the result is negative, Excel will display a series of hash signs (#####) instead of the correct time value. To fix this, you need to apply a custom time format that shows negative time values, such as -h:mm. To do this, follow the same steps as explained in the previous section.
Summing Multiple Times
Another common time calculation in Excel is summing multiple times, such as adding up the total hours, minutes, or seconds for a series of tasks, or for a group of employees. For example, you may want to know the total time spent on a project, or the total hours worked by a team.
To sum multiple times, you can use the SUM function as usual. For example, if the time values are in cells A2:A10, you can use this formula:
=SUM(A2:A10)
This will give you the total time in the default time format, such as 12:15:30. However, if the total time exceeds 24 hours, Excel will not display it correctly, unless you apply a custom time format that allows for more than 24 hours, such as [h]:mm:ss. To do this, follow the same steps as explained in the previous section.
