How to reduce the size of a pdf document in OS X

Depending on what program you used to create a PDF, the file size of your PDF file can be quite large. If you combine two or three PDF files together using preview, you can also end up with a bloated PDF file.  The best way to reduce PDF file size is with Acrobat professional, which can do all sorts of magic on PDF files. Sadly we can’t all afford Acrobat Professional, so here is a free way to make a PDF file smaller.

Reduce file size will degrade your photo quality. Use it wisely.

UPDATE: Here is a quicker way (thanks to Henry below for the tip)- you can now do this from within Preview!

You can reduce file size by using preview.
1. Open PDF file
2. Click “File” and then “Save As”
3. Under “Quartz Filter” drop down list, select “Reduce File Size”
4. Rename and save the file. [In case you do not like the quality.]


Firstly, open the PDF file in ColorSync utility. The ColorSync utility is found in the utility folder of the applications folder of your computer. If you don’t know how to find that, simply right click (or option click if you have a one button mouse) on the PDF file, and select from the menu open with,  ColorSync utility.


This will open your PDF file in colour sync utility. Go down to the bottom of the window to the drop-down menu on the left that says ‘Filters’  and select ‘reduce File Size’.  Then click the button in the bottom right  of the window that says ‘Apply’.


Select the filter that says reduce file size


This will go through and re-compress the images in your PDF to make the file size smaller.

The images will not be quite as sharp, but the field will be much smaller.

Don’t forget to save the file after you’re finished.

You may want to use ‘save as’  instead of ‘save’ so that you still keep the original (higher quality) version of your PDF file.




If you want to be able to change the quality of the file that is saved, check out this great article from macworld:


86 responses to “How to reduce the size of a pdf document in OS X”

  1. amit

    Great tip – thanks

    1. Rach

      Agree, extremely helpful!

  2. Charlene

    It doubled the size of my pdf?
    Is there any other way to reduce the size of a pdf file?

    1. The best way is to use Adobe Acrobat Professional – but it costs! I guess the free way doesn’t always work!

  3. Thx — works great. Reduced a 160 meg file to 3 megs. Yeow!

  4. tim

    When it reduced the size it inverted the colors of the pictures to be blacks and greens like an x-ray. Any thoughts?

    1. renato

      It works.


      I know people must come across problems when they try to reduce a huge PDF file down to a small file size. In my case, I was getting inverted colours from a file generated from Indesign. So I thought I might share this free alternative to all those programs out there, and if you don’t want to fork out huge amount of money for Acrobat Professional.

      This is going to be a solution for the Mac.
      Go to your Finder
      Click on Applications
      Click on your Utilities Folder
      Click on ColorSync
      Once its open, switch to the “Filters” panel (which will list all of the filters you currently have available)
      In the lower left, click on the “+” button which will create a new filter
      Name the filter whatever you want and press return.
      To the right of the filter’s name, choose the down arrow and a menu will pop up.
      From that pop-up menu, choose “Add Image Effects Component”, and from that menu choose “Image Compression”.
      Adjust the image compression Mode to JPEG.
      Adjust the image compression quality however you’d prefer.
      To the right of the filter’s name, choose the down arrow and a menu will pop up.
      From that pop-up menu, choose “Add Color Management Component”, and from that menu pick “Convert to Profile”.
      Pick sRGB IEC61966-2.1 | CMYK data | All objects
      The next time you use Preview to “Save As…”, you’ll have a new option under Quartz filters.
      The colours are not inverted and the file size has compressed.

      1. Tanya

        Brilliant! Thank you! :)

      2. Christina

        I would go for “brilliant”!
        The file was downsized to 20%, while the pictures remained clear.

      3. Toby

        Really helpful comment. Managed to retain the original quality and shrink the file down to 30% of the original size! Thank you!

  5. Alas, it didn’t work for me, either. Just left the file as it was- 4.5 mb

  6. Henry.

    You can reduce file size by using preview.
    1. Open PDF file
    2. Click “File” and then “Save As”
    3. Under “Quartz Filter” drop down list, select “Reduce File Size”
    4. Rename and save the file. [In case you do not like the quality.]

    Basically, reduce file size will degrade your photo quality. Pls use it wisely.

    1. Hugh1700

      Henry – this worked great for me. Thanks!

    2. shar

      great to know, that worked very well for me. thanks very much

      1. DS

        Thanks Henry, Works great!
        Reduced a file from 15.5MB to 238 KB, and the pictures look the same.

  7. Hi,
    you can duplicate the “reduce file size” filter and change the settings and save it with a new name. Then you can use the new filter in “Preview” to save PDFs with a smaler file size (choose “Quartz Filter” while saving in Preview).

    With LION you have to move the filters from


    to /Library/PDF Services/

    < 10.7 you can leave them in your path, Preview can use them directly.

    Have fun!

  8. when I reduce my pdf it changes all the colours into deep greens and blacks and I cannot make out any of the images? any one else have this problem?

  9. Suzy

    Thank you so much for the great tip. Worked like a gem!

  10. tet

    Thank you for this, you saved my life :) really helpful!

  11. Arne

    Tnx al lot file size went from 104 Mb to 376 Kb

  12. charlie

    Hi, thanks for this. it worked very well. Except when I went to open my PDF and save as to apply the filter. I opened the file on my desktop and my new filter wasnt appearing. Turns out I had to open the PDF from colour utility itself and then apply filter. Im not sure if this is common knowledge but I couldn’t understand why the new filter wasn’t showing under ‘export’. I have a brand new pro, not sure if something has changed recently.

    Anyway great work! Saved my day

  13. Daggor

    This worked well – reducing in Acrobat gave me a 10.7mb file. This reduced it to 3mb!!!

  14. Akonde

    It works but there was a drop in pix quality. How do I get back the pix quality?

  15. Juliette

    Thank you so much for this tip – it worked a treat – something I will not forget.


  16. Samantha

    It made my PDF document all pixley

    1. Yes that’s correct – reduced file size means less quality.

  17. hydra

    worked like a charm on OS X mountain line. reduced from 17MB file to like 300KB. :)

  18. JC

    This tip worked for me, thanks!

  19. Sudhakar

    Unbelievable.. colorsync utility reduced my pdf (containing images) size from 780MB to 4MB and not much loss in quality either. Awesome.

  20. MR

    When I reduced my pdfs it changed all the colours into green and black (negative images?) Any one else have this problem? How did you solve it?

  21. CJ

    If it is a written Doc PDF that you need to reduce change open with Preview, Click Save As, Under Quartz Filter select Black and White.

    This reduced my file size from 10.3MB to 2.5MB without losing the quality of the document itself.

  22. PG

    This was amazing. It reduced my 21.4 MB PDF file to 559 KB and it looks just the same. Thank you.

  23. Spencer


    Thanks! My file went from almost 8MB to 330K and looks great!


  24. Bradley

    Thank you, Great tip. Worked really well!!

  25. Kenn Hong

    If I want to save to RGB format how? I try all the filter, all is CMYK mode… HELP!!!

  26. C. Hawkins

    Easy Fix! Reduced my 90.1 MB PDF to 800 KB. Thanks a bunch!

  27. Also have a look at – it’s a great little tool that does good compression but maintains the quality.

    1. Eyrekr

      This website works for me!My file size reduced from 5.6MB to 1.1MB. However, I don’t know the reason why my file size doesn’t change after using Colorsync… Thanks anyway!! :)

    2. Obie

      fantastic stuff Matt!

  28. Biraj Naidoo

    Thanks for the great tip! Much appreciated.

  29. Mary Ann

    This information helped me immensely. Every file comes in as number 1. Is there a way to change that?

  30. Carol Bartles

    This recommendation is incredible. Thank you, Thank you so much.

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