Mar 09

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.

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:

76 Responses to “How to reduce the size of a pdf document in OS X”

  1. amit says:

    Great tip – thanks

  2. Charlene says:

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

  3. Harry says:

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

  4. tim says:

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

    • renato says:

      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.

  5. R says:

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

  6. Henry. says:

    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.

  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 says:

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

  10. tet says:

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

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