Using an Input Mask

When inputting time into a cell, it is easy to enter digits—that's what the numeric keypad is for, after all. What can really slow you down is the necessity to enter other characters, particularly ones that require the use of the Shift key. For instance, if you are entering times, it is easy to enter 230 for 2:30, but it is a pain to slow down by entering the colon.

Thus, you may wonder if there is a way to set up an input mask that will add the colon automatically. The good news is yes, there is. The bad news is no, there isn't. Sound confusing? Let me explain...

You can set up a custom format that will display your time in any format you want. For instance, you could use the following steps:

1. Select the cells you want to use for time input.
2. Display the Number tab of the Format Cells dialog box. (Click here to see a related figure.) In versions of Excel prior to Excel 2007, click Cells | Format | Number tab. In Excel 2007 display the Home tab of the ribbon and click the small icon at the bottom-right of the Number group.
3. In the Category list, choose Custom.
4. Replace whatever is in the Type box with #":"00 (a pound sign, quote mark, colon, quote mark, and two zeros).
5. Click on OK.

You can now enter your times using just digits. The problem (and this is the bad news) is that the cell doesn't really contain a time. If you enter 230 (for 2:30), it doesn't contain 2:30 as a time—it contains two hundred and thirty. Thus, you can't use the contents of the cell directly in time calculations.

To overcome this, you can use another column to show the entered digits converted into a time. All you need to do is use a formula to do the conversions. For instance, if the time you entered was in cell A3, you could use the following formula in a different cell to do the conversion:

=(INT(A3/100)/24)+((A3 - (INT(A3/100)*100))/1440)

Format the cell that contains the above formula so it displays one of the various time formats, and you are all set.