Here is a familiar problem:
You create a workbook to track some data. You ask your staff to fill up the data. Almost all the input data is fine, except the date column. Every one types dates in their own format.
Here is a fun, simple & powerful way to warn your users when they enter wrong dates.
Use conditional formatting
Here is a quick demo:

How to ensure cleaner dates with conditional formatting?
- Let’s say your users need to enter date input in cell C3.
- Select C3 and go to Home > Conditional Formatting > New Rule
- Select the rule type as “Use a formula…”
- Use a formula like this: =ISERROR(DAY($C$3))
- Set up formatting to highlight incorrect dates
- Done
Explanation for the formula:
We will assume that C3 contains a valid date and try to do some sort of date operation on it, like finding the day of month using DAY($C$3). If this returns an error, that means we have an invalid date.
So to check the error status, we use ISERROR().
A caveat: dates are numbers
Since Excel dates are numbers, technically, your users can type a number in C3 (like 7) and our conditional formatting won’t trigger the error.
Bonus tip: Adding conditional formatting to an entire column
To add conditional formatting to an entire column,
- Let’s say the date inputs go to column C, starting with C3 as first input
- Select all the cells in column C that will have dates
- Set up the conditional formatting with below rule:
- =ISERROR(DAY($C3))
Download example workbook
Click here to download a simple example workbook with this technique. Examine the conditional formatting in C3 & D3 to learn more.
Do you use CF to nudge your users in right direction?
Excel Conditional Formatting is one of my all time favourite features. I use liberal amounts of CF on all my Excel recipes. I think CF makes a great ingredient if you are collecting user inputs.
What about you? Do you use conditional formatting to make sure your inputs are clean? What techniques do you use? Please share your thoughts and tips in the comments area.
Here are few more awesome ways to use conditional formatting:

















9 Responses to “Show forecast values in a different color with this simple trick [charting]”
While this works in a pinch, it clearly "lightens" the colors of the entire chart. Depending on where you use this, it will be blatantly obvious that you don't know what you are doing and present a poor looking graph.
Why not separate the data into different segments when charting and have as many colors as you have data points? You might have to create a new legend and/or repeat the chart in "invisible ink", but it would be cleaner and more consistent when new or updated data becomes available.
While I think I agree that doing it "properly" via a second series is preferable, I don't necessarily agree that making the entirety of the "future" (data, gridlines, and even the axis) semi-transparent is "poor looking". I think it could be seen as adding more emphasis to the "future-ness" of the forecast data.
In short, it's another tool for the toolbox, even if it's never needed.
Simply and clever 🙂
Quick & effective, cool. thanks.
I always use the dummy series.
Nice little trick, thanks very much!
Two sets of data better. Control is much better.
You can use the same chart next month to see what is actual and what is forecast.
To use this trick, I think grid lines has to be removed, that will make the graphic much more sharp.
to be honest, i dont understand why there is needed to do this way... in this case horizontal lines will be pale as well. then why a just can't change the color of the line partly???
Great tutorial. Thanks for the tutorial!