You are here:

Excel/Calculating the average date from a list of dates with different years


QUESTION: Hello Mr, Umlas,

I have a list of 310 study stations and the dates that they were sampled over the past six sampling years (one sample date per station per year).  I am trying to calculate the average month/day that each station was sampled over the past six sampling years.  For example, station 1 was sampled on 8/12/1995, 8/15/1998, 7/25/2001, 8/13/2004, 8/11/2007, and 7/30/2010 and I need to calculate the average month/day (as well at the variation) the station has been sampled over the past sampling years.  I cannot find a solution online and my attempts have been unsuccessful.  

I am happy to provide you with any additional information that you need.  Any advice that you can offer would be greatly appreciated.  

Thank you for your time.


ANSWER: Just take the average:
I get 2/6/2003.

---------- FOLLOW-UP ----------

QUESTION: Thank you for your reply but that's not exactly what I am looking for.  I just want the average month/day...the year is not relevant.  

I used the formula =IF(ISNUMBER(B2), MONTH(B2)&"/"&DAY(B2), "") to extract just the month and day but if I try to average, I get #DIV/0!.  This happens even if I copy and paste only the values.  

Thank you again for your time,


MONTH(B2)&"/"&DAY(B2) will give you a TEXT string, like 8/12, not really a number, so when you average all the text strings you do get #DIV/0!
Try this (works:)
and fill down, and take the average.
The 2000 is totally an arbitrary year, but allows you to get the real average. You can format these all as M/D, and you'd see:
with an average of
About Excel
This topic answers questions related to Microsoft Excel spreadsheet (or workbook) stand-alone or Mircrosoft Office Excel including Excel 2003, Excel 2007, Office 2000, and Office XP. You can get Excel help on Excel formulas(or functions), Excell macros, charting in Excel, advanced features, and the general use of Excel. This does not provide a general Excel tutorial nor the basics of using a spreadsheet. It provides specific answers to using Microsoft Excel only. If you do not see your Excel question answered in this area then please ask an Excel question here


All Answers

Answers by Expert:

Ask Experts


Bob Umlas


I`m a Microsoft Excel MVP (Most Valuable Professional) and have been since the inception of the program in 1995. I can answer every kind of Excel question except: API, Importing/exporting to other programs (powerpoint, word,...) Also check out my in-person training link at


Worked with MS Excel since version 0.99 (on the Mac!). Was contributing editor to Excellence Magazine, having written >300 articles. John Walkenbach said of me "I finally met someone who knows as much about Excel as I do."

Excellence, The Expert, Microsoft

BA in math, Hofstra University, 1965

Awards and Honors
Led sessions for the Convergence 2004-2006 seminar on Excel tips & tricks

©2016 All rights reserved.