Merge 2 pdf files in Mountain Lion


With Mountain Lion (OSX 10.8) Apple have made it even simpler to join two pdf files together – you just need to drag any pdf file into the thumbnail window of an existing pdf file and the two will be merged together!

Note: this is different for different versions of OS X.

For older versions of OS X (10.6-10.7) click here.

For OS X 10.9 Mavericks click here.


This is a simple 4 click process… (1) Open the first pdf file, (2) Open the thumbnails draw (3) Drag in the second pdf file and (4) Save the new pdf. Here are some pictures to help you do it!

Step 1 – Double click the first pdf file to open it.


Step 2 – Switch to thumbnail view. You can also do this from the top menubar – in the View menu click Thumbnail.


Step 3 – Drag the second pdf file anywhere into the thumbnail window. This copies the whole pdf file in.


Step 4 – Save. It will overwrite the original pdf.


  • Some people are reporting this is not working. (See the comments below). I have no idea why except that maybe you have a different version of the Preview app. Try the instructions in this post even though you don’t have Leopard and it will work!
  • To make a new pdf preserving the original one use ‘Duplicate’ then ‘Save’.
  • To copy only one page, open the second pdf page in thumbnail view and drag just one page across.
  • This does not work with protected pdf files. (Protected pdf files are not common.) If a pdf file has been locked by the author you cannot change it without a password.
  •  It’s a little more complicated on older versions of OSX (eg Leopard, Snow Leopard and Lion) because the exact location that you drop the new pdf makes a difference – see this post for how to merge pdf files in Leopard, Snow Leopard or Lion (10.5,10.6 and  10.7)


72 responses to “Merge 2 pdf files in Mountain Lion”

  1. Ana Vilma

    Thank you very much! :)

    1. danR

      Just to repeat what others say: the simple drag-and-drop method in the article does NOT work in Mountain Lion, and it’s hard to believe the anonymous author didn’t simply save his/her work and never returned to the document, if using the same updated ML as others are having the same non-fix issues with.

      After multiple test docs, I’ve confirmed what others have said. Two methods:

      1. Go to Print, and rather than print, save the document as PDF there.
      2. You MUST drag and drop each PDF thumbnail ON TOP OF or OVERLAPPING the last thumbnail immediately above in the target docs thumbnails-column. Since I’ve added a ‘Save As’ command to my menu (Which Apple stupidIy removed in ML), I don’t have to do the duplicate nonsense.

      So you’ll probably find method 1 much more convenient.

  2. HelenB

    I did not know this was included in Mountain Lion. What an awesome feature! Thanks for explaining how it works. :-)

  3. John

    Thank you so much for such an easy way to merge 2 editable PDF files. That was so very easy and free.

  4. MuffinHead

    Great tip – but with a slight modification. You must drop the ‘incoming’ page on top of the existing page to make sure it copies, especially if there is only one page in the destination file.

    If you just drop it into the thumbnail bar it may just show as a second document in the same ‘viewer’.

    Once you have more than one page in the destination file you should see a faint line at the bottom of the thumbnail bar – make sure you drop in new pages above that line.

    1. Hans

      MuffinHead: Thanks for that additional info. It didn’t work for me because of this particular problem – I had only one page. You’ll know that the pages are combined into one when you see them within a collapsible/expandable title bar of the document in the thumbnail window.

      For the poster of the article. Awesome job of explaining this How To! Thanks

    2. Mixa

      Side effect: Dropping a file on top of a one-page file produces a huge file: 15 kb + 292 kb = 4,9 Mb. But if I drop the file into the thumbnail bar below the first page, select all, print and save as pdf: 15 kb + 292 kb = 713 kb. Why the difference? By the way, batch pdf merger produces only 341 kb.

      1. Yes! “print and save as pdf” was exactly what I needed. My three one-page pdf files didn’t combine into one until I did that. Thank you!

    3. Yes, THANK YOU for adding this tip. It was exactly the problem I was having & couldn’t figure out. So frustrating. So again, thank you.

    4. SusanneM

      Thank you MuffinHead, this did the trick, great help ☺

  5. Brett

    Thanks for this. Found out that you have to drag the other PDF’s inside of the original pdf in order for it to merge.

  6. Richard Roper

    This worked up to a point – but when I tried to save it the document reverted back to the original. I even tried duplicating then saving but even the copy just reverts back. Any help on what I’m doing wrong?

    1. Wayne

      Are you sure you have Mountain Lion (10.8)? If not read this article:

      1. dustin

        i’m having the same problem as richard roper. i try to save it but the pdf’s won’t stay together after i close and then reopen it. and i have 10.8.

  7. Hal

    I have 10.8.2 and I also have the problem as state earlier. It looks fine until I duplicate or save. The files all revert back except for the duplicate. Can you help?

  8. Chazz

    Richard, I had the same issue. Turned out I was trying to merge two .jpegs (scanned documents) in Preview, not .pdfs.

    May or may not be your case too.

    1. Maureen

      I found that I was trying to merge .jpegs too, but like some others have said a good work around is open all of the .jpegs in viewer and then print to PDF. They will all be merged and in PDF form instead of .jpeg. Good luck all!

  9. Sophie

    Step 3 says that you can drag the next pdf file into anywhere into the thumbnail window which is possible but when you have a book that’s broken into a number of different pdf files, dragging them anywhere, puts the pages in the wrong order.

  10. Michal

    Thanks a lot!!! I was just looking for a programme to do so :-)

  11. Terryl

    I’m having the same problem as Richard Roper, and I (for sure) have 10.8.2. Also can’t get an ‘incoming’ image to drop on top of the existing image (as MuffinHead described); it will only go onto the left (thumbnail) part of the screen. Even when I put it above the first (only) image there, it saves as whatever image is highlighted. Highlighting everything makes no difference – it saves as the original image. Frustrating! What am I doing wrong?

  12. Myles

    I’m having the same “save” problem, and I think it may be the security settings that the file embeds from Word… It looks like there are document restrictions, set as a standard in Word. Can’t seem to figure out how to reset them

  13. Chuck

    Didn’t work for me in Mountain Lion. It only copied the first page of the new pdf into the original one.

  14. Manny

    I’m having the same problem as others. I can put multiple pdf files into one “document” in preview so that I can go from one to the other. But saving them does not merge them into one. I even selected all the pages in the thumbnails section before I did a save, and it still didn’t work. When I try Duplicate, only the last page selected gets duplicated, not all of them.

    Not sure about any security settings or restrictions. The pages I’m trying to merge were forms I scanned. I didn’t set any restrictions when I scanned them.

    1. Manny

      Disregard my last. It DID work if you do what MuffinHead said to do above.

  15. Jennifer Harper

    Thank you so much. I can’t believe how easy this was.

  16. Stumpweasel

    Brilliant, I’ve now got one doc not two but it’s on my Mac. If only the office PC network could cope with the file size via email. Guess I’ll have to find that memory stick…

  17. Kev K

    Thanks so much this saved me money and it is not bad as I thought. Very simple.

  18. Laura

    Holy crap! It finally worked! Thanks so much!

    1. MartyA

      With all of the positive responses I am truly embarrassed because I don’t get anything. I am working with OS 10.8.2 and Adobe Reader 11.0.02.

      I had trouble finding Thumbnail which for me was,

      View/(Show/Hide)/Navigation Panels/Page Thumbnails.

      When I try to deposit the file onto anything in the Thumbnail nothing happens.

      It’s tough growing old!

      1. Use Preview – not Acrobat Reader.

  19. MartyA

    With my deepest apologies. I don’t know why after hours of trying I waited to submit a reply before I suspected that you all were working in Preview and not Adobe Reader.

    I think that I can learn the correct procedure. Thanks, if you were patient with me.

  20. Ray Barrick

    1. I had the same problem with saving the new, multi-page document. There was a security setting in the PDFs that did not allow document assembly. I was, however, able to “print” the assembled document, adn selected “PDF, Save As” (on the lower left of the print window.) I lost the links, but otherwise is OK.

    2. I see that I can annotate the PDF, but is there a way to add page numbers?

    3. Can I add bookmarks that will link sections of the document to the Table of Contents?

  21. Ram

    For many who are still unable to do it, I am nearly certain it is because the file is protected (as the instructions above mention at the end). I kept trying to merge some files and they kept ending up as separate files. And even the advice from muffinhead did not seem to work.

    I then downloaded a free app named PDF unlock, it unlocks PDF files that are locked for printing or merging (not password protected files that won’t even open). Once unlocked, the instructions above worked like a charm in Mac’s own Preview app where the PDF files merged as they should.
    The PDF unlock app can be downloaded here:

  22. MRM

    I had the same problem as everyone else. What worked for me was once I had the thumbnails all set (6 pages total) I went to Preview–> Print —> Save as —> PDF. It worked just fine. It wouldn’t let me save it, but if I went to print it and saved it as a PDF at that point it worked like a charm.

  23. Lee

    TYPO ??
    (2) Open the thumbnails draw

    Did you mean:
    (2) Open the thumbnails drawer

  24. Erica

    I am not understanding this at all. I have 10.8.3 & can’t figure it out.
    Any additional info would be helpful!

  25. Joel

    “This is a simple 4-click process…” that the article did not get right. Agreed with commenter MuffinHead, open the first page, then “drop the ‘incoming’ page on top of the existing page to make sure it copies” (not “anywhere” as the article says). Is it possible to fix the article or show a couple of options? It’s a shame that such a crucial detail was omitted.

  26. Michael

    Adding to Joel it would be nice to add that one has to use the viewer app to do that. I’ve installed Adobe Reader on my Mac and it’s determined as standard application to open pdf files. Took me a while to work out how it actually is done. Anyways, it worked perfectly without any of the above mentioned issues.

  27. Lars

    This is extremely frustrating. It “works”….until you save it. When you re-open it or export it, it doesn’t retain the other pages. Over 10 years ago, I briefly had a PC, and hated it. The more I know Mountain Lion, the more it reminds me of the PC. Any insight would be appreciated, although it is time sensitive and therefore probably be a little late.

  28. Peter

    Excellent, you have saved me heaps of time and effort. I love how simple everything is on a Mac.

  29. BILL

    The new version of Mountain Lion 10.8.4 blocks this procedure.
    It will let you form a multi-page pdf, but it will not let you save it as a grouped document. It will only give you the original page single page you started with.
    Just stupid there’s no Save-As command to rename the file.
    I tried Duplication, Save, Drag and Drop, all forms are now blocked.
    Plus, Adobe will not read or show pdf’s created by Preview.
    Seems to be a war going on between the companies.

    1. Gianluka

      It actually works perfectly. You must drag&drop the extra files on top of the THUMBNAIL of the existing page to make sure it add the new PDF’s to the original one. (YOU WILL SEE A ‘PLUS ICON’ APPEAR WHEN YOU DRAG OVER IT) Then just save it. Cheers ;)

      1. Kathy

        I would have never figured that out unless I read your comment. Thanks for saving me hours of frustration by just a drop and click :) Awesome!!!

      2. Joanne Kim


  30. BILL


    Once you create the multi-page PDF document per the instructions above.
    You must do a print to safe pdf as a new document.
    When you click print, then chose the save as PDF option.
    Then you will be able to save your complete file as a new PDF.

    No other way works.

    1. Nicole

      I thought I was the only one who was having this problem Bill! I was clicking and dragging all over the place but nothing was working!!
      Clicking ‘Print’ and then ‘Save as PDF’ was the only way I could save a multi document version, everything else was just saving one page at a time!
      Thank you BILL!!

    2. Rodrigo

      YOU THE MAN BILL, you’re absolutely right: no other way works!

    3. Mary

      After trolling the internet for an hour I finally found out how. Thanks Bill!

    4. Sumit

      Thank you Bill! I have been looking for this solution for hours!!!

    5. Inger Nordin

      Thanks – with this instruction it is working! So happy!

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