Merging pdf files in Big Sur is the easiest it’s ever been. You just need to be in thumbnail view and drag one pdf fiel into the other one, save, and they will merge.

1. Double click any pdf file. (It will open on Preview)
2. Select View Thumbnails in the sidebar.
3. Drag any other pdf file into the sidebar and let it go there.
4. Save the new pdf file.

Here’s how to do it with pictures.

1. Open in Preview

Double click any pdf file and it will open in ‘Preview.’ You can check that it has opened in preview because the name “Preview” should appear in the top menu next to the Apple symbol. If for some reason it did not open in Preview, then you can right click or option click on the file when you are opening it and select ‘Open with Preview’.

2. Make sure you can see the sidebar and that you can see the thumbnails.

In the left-handside of the preview window they should be a side bar out to the side where you can see a picture of each page in the PDF file. If you cannot see the side bar, turn it on.

3. Drag in a second pdf file.

All you need to do is select any PDF file and drag it onto that sidebar. Where ever you put it, it will merge into the existing PDF file at exactly that spot.

4. Save the file.

Apple-S or File:Save will save the original file with the new file added.

Notes:

If you just want to merge some of the pages from the second PDF file, open the second PDF file in Preview and drag the individual pages across from one side bar to the other side bar.