If you’re working on a project, you might need to keep track of the time that you spend on its tasks. Later, you can tell a client how much time you’ve spent on their project, and get paid for your work. Or, you can use the time data to see how much of your day is spent on productive tasks, and how much is spent Googling and tweeting.

### Enter the Current Time

To quickly enter the current time in Excel, you can use the keyboard shortcut: **Ctrl + Shift + ;**

- When you start a task, use the shortcut to enter the start time in one cell.
- When you finish working on a task, use the shortcut in an adjacent cell, to enter the end time.

In the screen shot below, the Task start times are entered in column B and the end times are entered in column C.

### Calculate the Elapsed Time

Based on the start and end times, you can calculated the elapsed time, by subtracting the start time from the end time.

In this example, I’ll calculate the time in cell D2, using this formula:

**=C2-B2**

### Format the Elapsed Time

There is a 15 minute difference in the start and end times in this example, but the result cell is showing a time – 12:15 AM

To see the result as hours and minutes of elapsed time, we’ll change the formatting:

- Select cell D2, where the elapsed time is calculated
- Press Ctrl + 1 to open the Format Cells dialog box
- On the Number tab, click the Time category
- Click on the 37:30:55 format, then click OK

This format displays an overall total of hours, minutes and seconds. Cell D2 now shows the elapsed time of 15 minutes.

### Formula Error When No End Time

The formula works well if a start time and an end time have been entered. But there is a problem if only the start time has been entered.

The result in cell D3 is a negative number, because the start time is subtracted from zero (the value of empty cell C3).

Excel displays negative dates and times as #####.

To avoid this problem, we’ll change the formula in cell D2, and copy it down to cell D3:

**=IF(C2="",0,C2-B2)**

Now, the formula checks cell C2, and if it is empty, the formula result is zero.

### Formula Error After Midnight

If you’re burning the midnight oil on those client projects, you’ll run into another error. In the screen shot below, the start time for Task 3 is 10:30 PM, and I worked past midnight – ending at 12:30 AM.

The formula result is a negative number, because the end time is smaller than the start time.

To fix this problem, we’ll change the formula one last time. If the start time is greater than the end time, we’ll assume that the task ended the next day.

In that case, we’ll add 1 to the end time, which is the equivalent of adding a full day to the end time. That makes the end time greater than the start time, and the calculation will work correctly.

**=IF(C2="",0,IF(B2>C2,1,0)+C2-B2)**

### Add the Task Times

To get the total time for all your tasks, use the SUM function. It should automatically format the total cell in the 37:30:55 format, but if not, you can format the cell manually.

**=SUM(D2:D4)**

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