This is second part of 2 part series on conditionally formatting dates in excel.
In yesterday’s post we have learned how to conditionally format dates using excel. In this article, you will learn how to use these conditional formatting tricks to highlight repeat customers in a list of sales records.
The problem: Highlighting repeated customers in a list
Let us say you run a small retail store. And you want to give special discounts to all the repeat customers.
Repeat customer is someone who bought at least twice from you in last 30 days. (If the person bought twice but the gap between 2 purchases is more than 30 days they are not repeat customers).
The Data:
Let us assume your sales data has these 2 columns – customer ID and purchase date. I have shown first few rows here. Let us assume the data is in the range B4:C53.

Finding if a customer is repeat – The Formula:
If we just want to highlight without considering the purchase dates,
we can use a simple formula like =COUNTIF($B4:$B53,$B3)>1 in the conditional formatting applied over the range B4:C53.
But we need to consider the date as well,
hmm, now that is tricky !??
May be time for a sip of that coffee. Go take it, I am waiting..,
How about the SUMPRODUCT? We all know that sumproduct formula can be used to test more than one condition.
The formula:
=IF(C4>TODAY()-30,IF(SUMPRODUCT(--($B$4:$B$53=B4),--($C$4:$C$53>(TODAY()-30)))>1,"R","N"),"N")
Now that is one lengthy badass formula. Like Sergeant Martin Riggs. Bad, but still cool.
So what is this formula really doing? It is going to give us “R” if a customer is repeat and “N” if not. See this explanation to understand how it works.

Note: the double dashes “–” make the values as 0s and 1s from a bunch of “trues” “falses”. To know why sumproduct is such a beautiful and robust formula look no further.
The Conditional Formatting
Now that you have figured out the formula to determine a customer is repeat or not, applying conditional formatting is a piece-o-cake.
Just select the range B4:C53, go to conditional formatting and select “formula” option. Now specify the above formula and check if its output is “R” and apply formatting.
I am not telling you how to do this. It is your homework. Go figure!
That is all. Your workbook now highlights repeat customers in the last 30 days. Remember, as you reopen the file a week later, the highlighting logic changes since the date has changed.
Download the example workbook
Click here to download the example workbook and understand how to highlight repeat customers using conditional formatting. The file works in Excel 2003+.
What is your experience?
Share your tips and ideas on using conditional formatting with dates. What are the situations you usually face and how to solve them? I am never too old for this, so please share.

















30 Responses to “Great News: Chandoo becomes MVP”
Congratulations! It's well deserved. 🙂
This is amazing. Hearty congratulations and a rocking new year ahead!!!
Congrats! I have learnt alot from your site... and the most important is learning how to achieve the most with the simplest concepts.
Thanks for the excel calendar. Is it possible to get a simple big fonted calendar printable on an A4 size paper without any distracive notes or visuals? BTW, I have already signed up for your newsletter. With warm regards and
Gratefully yours
50+ year old CHarish.
Hey Chandoo,
Great to hear that. Congratulations! The best new year gift, I would say. Keep it up, u've been doing extraordinary work for the excel users community.
Regards,
Pankaj Verma
Congrats dude... fantastic news!
congratulations! your site is great, this is well deserved
Rich
I recently found your site, I visit many. The tips that you provide are in the top 1% of all the sites I visit. Keep on Excelling.
Arnold
South Africa
Congratulations, Chandoo! That's a great way to start the year and make the PHD even better.
Congratulations, Chandoo.
Your site is one of most useful on the net. Happy new year and lot of ideas you will present for us.
Congrats.
Just read your name in an email from Abhishek. Well deserved.
Congratulations, and Happy New Year.
Greetings from Rio de Janeiro my friend! You trully deserve it!
Nive way to start 2009! Keep up the good work!
FC
That was quite forseeable , so you have now really got your PhD in excel.
Anyways Chandoo you have made excel a real Fun doo
I will like you to write some more on INDEX and MATCH function in near future.
@Hey Chandoo ! Congrates....
Ab to treat mangta hai !
Well deserved Chandoo!!
Congrat's!! Very well deserved 🙂
i always browsed mr.excel and used to see MVP writtne below names of people who used to solve queries in excel forum there......i just used to admire as to what they have special in them that they are MVP......
but now i got my answer...............u deserve it man..........
@All: thanks everyone 🙂
Congratulations Chandoo, nice job!
Chandoo,
A well deserved recognition and a good start to the New Year. Continue your good work.
Subbu
Many Congratulations.
You deserve a Ph.D. 🙂
congrats.....
Congrats dude. Rock on!
[...] charting community in 2007 and has been growing strongly ever since. In year 2009, I have received the MVP award from Microsoft. Just few days back I have become a dad [...]
Respected sir,
I am impressed!.... Good job done.. Keep it up...
Sir, How to be a MVP certified person. What level of knowledge is required for it? send me links if possible.
Please reply...
Regards,
Dipak Khalasi.
Dipak -
The first thing you need to cultivate is the ability to search the web effectively. You could start by Googling "Microsoft MVP".
[...] boy and girl which has been made hectic and incredibly fun ever since to their life.He has been awarded MVP status in 2009 by Microsoft(and renewed in 2010,2011 & 2012).His MVP profile is here.If you want to contact him direct then [...]
Congrats Chandoo!!
[…] Chandoo becomes MVP […]