If you are familiar with Excel functions, you can combine the Right function, Find function, Substitute function and Len function to extract extensions from filenames. Please do as follows:

Select a blank cell next to the file names, and enter the formula =RIGHT(A2,LEN(A2)-FIND("|",SUBSTITUTE(A2,".","|",LEN(A2)-LEN(SUBSTITUTE(A2,".",""))))) into it, and then drag the Fill Handle to the range as you need. See below screenshots:

Note: In above formula, A2 is the filename cell that you will extract extension from. And you can change it based on your needs.

If you have Kutools for Excel installed, its Extract Text utility can help you extract extensions from filenames easily. Please do as follows:

1. Select the filename cells that you will extract extensions from, and click the Kutools > Text > Extract Text.

2. In the opening Extract Text dialog box, type .*  into the Text box, click the Add button, and then click the Ok button.

Note: If there already has extract rules in the Extract list, please clear all the old rules except the new added one.

3. In the new opening dialog box, specify the first cell address of destination range, and click the OK button.

Now you will see all extensions of filenames are extracted and output into the specified range. See below screenshot:

Apart from Extract Text utility, you can also apply Kutools for Excel’s Split Cells utility to extract extensions from filenames. Please do as follows:

1. Select the filename cells that you will extract extensions from, and click the Kutools > Text > Split Cells.

2. In the popping out Split Cells dialog box, check Split to Columns option, check Other option, type . into the below box, and click the Ok button.

3. In the second Split Cells dialog box, specify the first cell address of destination range, and click the OK button.

Now you will see the filenames column is split into two columns: filename column and extension column as below screenshot shown.

If necessary, please delete the new filename column based on your needs.

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