Select a blank cell, for example Cell C3, enter the formula =IF(C2=0,"NA",AVERAGE(A2:INDEX(A:A,C2))) into it, and then press the Enter key.

Notes:

(1) In the formula of =IF(C2=0,"NA",AVERAGE(A2:INDEX(A:A,C2))), A2 is the first cell of the dynamic range in Column A, C2 is the cell with number which equals to row number of last cell of the dynamic range. And you can change them based on your needs.

(2) You can also apply the formula =AVERAGE(INDIRECT("A2:A" &C2)) to calculate the average of dynamic range based on Cell C2.

Sometimes, the range is dynamic based on the criteria users input. In this case, you can calculate the average of dynamic range as below steps.

1. Batch define names for each row and each column in the specified range.

In our case, select the Range A1:D11, click the Create names from selection button  in the Name manager pane; check both Top row option and Left column option in the Create Names from Selection dialog box, and click the OK button. See screenshot below:

Note: The Name manager pane is one component of Navigation Pane, which is provided by Kutools for Excel and includes: (1) list all opening workbooks and sheet tabs; (2) list and insert AutoText entries; (3) list all name ranges; (4) List all column names of active sheet; (5)  Advanced find and replace. Read More  Have a no-limitation Trial

2. Select the blank cell you will place the dynamic average at, enter the formula =AVERAGE(INDIRECT(G2)) (G2 is the dynamic criteria users input, and it will be one of row headers or column headers of the specified range.) into it, and press the Enter key.

And now the average will dynamically change based on the criteria users input in the Cell G2. See screenshot above.

Automatically Count/Sum/Average cells by fill color in Excel

Sometimes you mark cells by fill color, and then count/sum up these cells or calculate these cells’ average later. Kutools for Excel’s Count by Color utility can help you solve it with ease.