 Please Note: This article is written for users of the following Microsoft Excel versions: 2007, 2010, 2013, 2016, 2019, and Excel in Office 365. If you are using an earlier version (Excel 2003 or earlier), this tip may not work for you. For a version of this tip written specifically for earlier versions of Excel, click here: Calculating Averages by Date.

# Calculating Averages by Date by Allen Wyatt
(last updated April 18, 2020)

Suppose that you have a huge worksheet that contains all the rainfall readings for a given locale for the past hundred years or so. In cells A2:A42733 you have the dates, 1 January 1903 through 31 December 2019. In cells B2:B42733 you have the measurements for each date. Further, some of the measurements can be zero (if there is no rainfall for the day) or blank (if no reading was taken that particular day). With all this information, you want to calculate the average historic rainfall for any given day of the year.

One solution involves the use of array formulas, as detailed here:

1. Select all the cells in column A that contain dates and assign this range the name Dates.
2. Select all the corresponding cells in column B; these contain the rainfall data for the dates in column A. Assign this range the name Rainfall.
3. In column D, starting in cell D2, place all the days of the year. You should end up with D2 through D366 filled with dates.
4. In cell E2, enter the following array formula (terminate the formula by pressing Shift+Ctrl+Enter). The result of the formula is the sum of all the cells in the Rainfall range, for the date specified in cell D2.
5. ```=SUM((MONTH(Dates)=MONTH(D2))*(DAY(Dates)=DAY(D2))*Rainfall)
```
6. In cell F2, enter the following array formula (terminate the formula by pressing Shift+Ctrl+Enter). The result of the formula is the number of cells in the Rainfall range, for the date in cell D2, that have a value in them.
7. ```=SUM((MONTH(Dates)=MONTH(D2))*(DAY(Dates)=DAY(D2))*(Rainfall<>""))
```
8. In cell G2, enter the following regular formula. This is your average for the date in cell D2.
9. ```=IF(F2<>0,E2/F2,"")
```
10. Select the range E2:G2 and copy down for all the dates shown in column D.

This approach works, but it takes quite a while to calculate. This is because you effectively entered 822 array formulas, each checking over 42,000 cells. This is a lot of work, and consequently it may appear like your machine has "hung" after you complete step 7. It has not hung; it will just take it a while to complete the calculations.

To decrease the number of calculations that must be performed, you can use a variation on the above steps. Follow steps 1 through 3, as noted, and then place the following array formula into cell E2:

```=AVERAGE(IF((Dates<>0)*(Rainfall<>0)*(MONTH(Dates)=MONTH(D2))*(DAY(Dates)=DAY(D2)),Rainfall))
```

You can then copy the formula down for all the dates shown in column D. The result of this formula is the actual average rainfall, the same as had been shown in column G in the previous approach.

You can reduce the calculation overhead even further by simply getting rid of all the table that calculates the averages for every day of the year. With your dates and rainfall in columns A and B, follow these steps:

1. Select all the cells in column A that contain dates and assign this range the name Dates.
2. Select all the corresponding cells in column B; these contain the rainfall data for the dates in column A. Assign this range the name Rainfall.
3. In cell D2, place the date for which you want to check the average rainfall. (The year isn't important; only the month and day are used in the calculation.)
4. Enter the following formula into cell E2:
```=AVERAGE(IF((Dates<>0)*(Rainfall<>0)*(MONTH(Dates)=MONTH(D2))*(DAY(Dates)=DAY(D2)),Rainfall))
```

That's it. Now, you can change the date in cell D2 as desired, and cell E2 will always indicate the average rainfall for that date. The formula in cell E2 is the same as the formula used in the last approach; the difference is that you aren't calculating it for all the days in a year, and thus the calculation is done much quicker.

Another approach involves the use of Excel's filtering capabilities. Before you can use them properly, however, you must create a column that shows only the month and day for each date in your data. Use this formula in cell C2:

```=MONTH(A2) & "-" & DAY(A2)
```

Now, turn on AutoFiltering (display the Data tab on the ribbon | Sort & Filter group | Filter) and use the drop-down list at the top of the new column to select the date for which you want an average. You then use the following formula, placed in any cell desired, to show the average rainfall for the selected date:

```=SUBTOTAL(1,B:B)
```

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (10319) applies to Microsoft Excel 2007, 2010, 2013, 2016, 2019, and Excel in Office 365. You can find a version of this tip for the older menu interface of Excel here: Calculating Averages by Date.

##### Author Bio

Allen Wyatt

With more than 50 non-fiction books and numerous magazine articles to his credit, Allen Wyatt is an internationally recognized author. He is president of Sharon Parq Associates, a computer and publishing services company. ...

##### MORE FROM ALLEN

Resetting Toolbars to Their Default

Customize Word enough, and you may at some point want to set the toolbars back to their original condition. Here's how to ...

Discover More

Excel Applies Scientific Notation to Imported Data

Using Excel to import data from another source (such as a database) is a great approach to analyze that data. What do you ...

Discover More

Rounding Time

Need to round the time in a cell to a certain value? There are a couple of ways you can do this with a formula.

Discover More Create Custom Apps with VBA! Discover how to extend the capabilities of Office 2013 (Word, Excel, PowerPoint, Outlook, and Access) with VBA programming, using it for writing macros, automating Office applications, and creating custom applications. Check out Mastering VBA for Office 2013 today!

##### More ExcelTips (ribbon)

Including Weeks in Elapsed Time

When showing how much time has elapsed between two dates, it is sometimes helpful to express the result in terms of ...

Discover More

Leap Years and Fiscal Periods

Need to figure out when a fiscal year ends when that period does not correspond to the calendar year? Here are some ways ...

Discover More

Ages in Years and Months

Calculating an age is a common task when working with dates. If you want to figure out the number of years and months ...

Discover More
##### Subscribe

FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."

If you would like to add an image to your comment (not an avatar, but an image to help in making the point of your comment), include the characters [{fig}] (all 7 characters, in the sequence shown) in your comment text. You’ll be prompted to upload your image when you submit the comment. Maximum image size is 6Mpixels. Images larger than 600px wide or 1000px tall will be reduced. Up to three images may be included in a comment. All images are subject to review. Commenting privileges may be curtailed if inappropriate images are posted.

What is four less than 7?

There are currently no comments for this tip. (Be the first to leave your comment—just use the simple form above!)

##### This Site

Got a version of Excel that uses the ribbon interface (Excel 2007 or later)? This site is for you! If you use an earlier version of Excel, visit our ExcelTips site focusing on the menu interface.