How to conditionally format dates and time in Excel with formulas and inbuilt rules

How to highlight weekends in Excel

Regrettably, Microsoft Excel does not have a built-in calendar similar to Outlook's. Well, let's see how you can create your own automated calendar with quite little effort.

When designing your Excel calendar, you can use the =DATE(year,month,date) function to display the days of the week. Simply enter the year and the month's number somewhere in your spreadsheet and reference those cells in the formula. Of course, you could type the numbers directly in the formula, but this is not a very efficient approach because you would have to adjust the formula for each month.

The screenshot below demonstrates the DATE function in action. I used the formula =DATE($B$2,$B$1,B$4) which is copied across row 5.

Your Excel calendar is almost done, and you only need to change the color of weekends. Naturally, you are not going to color the cells manually. We'll have Excel format the weekends automatically by creating a conditional formatting rule based on the WEEKDAY formula.

1. You start by selecting your Excel calendar where you want to shade the weekends. In our case, it is the range $B$4:$AE$10. Be sure to start the selection with the 1^st date column - Colum B in this example.
2. On the Home tab, click Conditional Formatting menu > New Rule.
3. Create a new conditional formatting rule based on a formula as explained in the above linked guide.
4. In the "Format values where this formula is true" box, enter the following WEEKDAY formula that will determine which cells are Saturdays and Sundays: =WEEKDAY(B$5,2)>5
5. Click the Format… button and set up your custom format by switching between the Font, Border and Fill tabs and playing with different formatting options. When done, click the OK button to preview the rule.
   

Now, let me briefly explain the WEEKDAY(serial_number,[return_type]) formula so that you can quickly adjust it for your own spreadsheets.

• The serial_number parameter represents the date you are trying to find. You enter a reference to your first cell with a date, B$5 in our case.
• The [return_type] parameter determines the week type (square brackets imply it is optional). You enter 2 as the return type for a week starting from Monday (1) through Sunday (7). You can find the full list of available return types here.
• Finally, you write >5 to highlight only Saturdays (6) and Sundays (7).

The screenshot below demonstrates the result in Excel 2013 - the weekends are highlighted in the reddish colour.

Tips:

• If you have non-standard weekends in your company, e.g. Fridays and Saturdays, then you would need to tweak the formula so that it starts counting from Sunday (1) and highlight days 6 (Friday) and 7 (Saturday) - WEEKDAY(B$5,1)>5.
• If you are creating a horizontal (landscape) calendar, use a relative column (without $) and absolute row (with $) in a cell reference because you should lock the reference of the row - in the above example it is row 5, so we entered B$5. But if you are designing a calendar in vertical orientation, you should do the opposite, i.e. use an absolute column and relative row, e.g. $B5 as you can see in the screenshot below:

How to highlight holidays in Excel

To improve your Excel calendar further, you can shade public holidays as well. To do that, you will need to list the holidays you want to highlight in the same or some other spreadsheet.

For example, I've added the following holidays in column A ($A$14:$A$17). Of course, not all of them are real public holidays, but they will do for demonstration purposes : )

Again, you open Conditional Formatting > New Rule. In the case of holidays, you are going to use either MATCH or COUNTIF function:

• =COUNTIF($A$14:$A$17,B$5)>0
• =MATCH(B$5,$A$14:$A$17,0)

The following image shows the result in Excel 2013:

Conditionally format a cell when a value is changed to a date

It's not a big problem to conditionally format a cell when a date is added to that cell or any other cell in the same row as long as no other value type is allowed. In this case, you could simply use a formula to highlight non-blanks, as described in Excel conditional formulas for blanks and non-blanks. But what if those cells already have some values, e.g. text, and you want to change the background color when text is changed to a date?

The task may sound a bit intricate, but the solution is very simple.

1. First off, you need to determine the format code of your date. Here are just a few examples:
   • D1: dd-mmm-yy or d-mmm-yy
   • D2: dd-mmm or d-mmm
   • D3: mmm-yy
   • D4: mm/dd/yy or m/d/yy or m/d/yy h:mm

   You can find the complete list of date codes in this article.

2. Select a column where you want to change the color of cells or the entire table in case you want to highlight rows.
3. And now create a conditional formatting rule using a formula similar to this one: =CELL("format",$A2)="D1". In the formula, A is the column with dates and D1 is the date format.

   If your table contains dates in 2 or more formats, then use the OR operator, e.g. =OR(cell("format", $A2)="D1", cell("format",$A2)="D2", cell("format", $A2)="D3")

   The screenshot below demonstrates the result of such conditional formatting rule for dates.
   

How to highlight rows based on a certain date in a certain column

Suppose, you have a large Excel spreadsheet that contains two date columns (B and C). You want to highlight every row that has a certain date, say 13-May-14, in column C.

To apply Excel conditional formatting to a certain date, you need to find its numerical value first. As you probably know, Microsoft Excel stores dates as sequential serial numbers, starting from January 1, 1900. So, 1-Jan-1900 is stored as 1, 2-Jan-1900 is stored as 2… and 13-May-14 as 41772.

To find the date's number, right-click the cell, select Format Cells > Number and choose the General format. Write down the number you see and click Cancel because you do not really want to change the date's format.

That was actually the major part of the work and now you only need to create a conditional formatting rule for the entire table with this very simple formula: =$C2=41772. The formula implies that your table has headers and row 2 is your first row with data.

An alternative way is to use the DATEVALUE formula that converts the date to the number format is which it is stored, e.g. =$C2=DATEVALUE("5/13/2014")

Whichever formula you use, it will have the same effect:

Conditionally format dates in Excel based on the current date

As you probably know Microsoft Excel provides the TODAY() functions for various calculations based on the current date. Here are just a few examples of how you can use it to conditionally format dates in Excel.

How to highlight dates within a date range

If you have a long list of dates in your worksheet, you may also want to highlight the cells or rows that fall within a certain date range, i.e. highlight all dates that are between two given dates.

You can fulfil this task using the TODAY() function again. You will just have to construct a little bit more elaborate formulas as demonstrated in the examples below.

Formulas to highlight past dates

• More than 30 days ago: =TODAY()-$A2>30
• From 30 to 15 days ago, inclusive: =AND(TODAY()-$A2>=15, TODAY()-$A2<=30)
• Less than 15 days ago: =AND(TODAY()-$A2>=1, TODAY()-$A2<15)

The current date and any future dates are not colored.

Formulas to highlight future dates

• Will occur in more than 30 days from now: =$A2-TODAY()>30
• In 30 to 15 days, inclusive: =AND($A2-TODAY()>=15, $A2-TODAY()<=30)
• In less than 15 days: =AND($A2-TODAY()>=1, $A2-TODAY()<15)

The current date and any past dates are not colored.

How to shade gaps and time intervals

In this last example, we are going to utilize yet another Excel date function - DATEDIF(start_date, end_date, interval). This function calculates the difference between two dates based on the specified interval. It differs from all other functions we've discussed in this tutorial in the way that it lets you ignore months or years and calculate the difference only between days or months, whichever you choose.

Don't see how this could work for you? Think about it in another way… Suppose you have a list of birthdays of your family members and friends. Would you like to know how many days there are until their next birthday? Moreover, how many days exactly are left until your wedding anniversary and other events you wouldn't want to miss? Easily!

The formula you need is this (where A is your Date column):

=DATEDIF(TODAY(), DATE((YEAR(TODAY())+1), MONTH($A2), DAY($A2)), "yd")

The "yd" interval type at the end of the formula is used to ignore years and calculate the difference between the days only. For the full list of available interval types, look here.

And now let's create an Excel conditional formatting rule to shade different gaps in different colors. In this case, it makes more sense to utilize Excel Color Scales rather than create a separate rule for each period.

The screenshot below demonstrates the result in Excel - a gradient 3-color scale with tints from green to red through yellow.