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.

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:

84 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!

  11. Arne says:

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

  12. charlie says:

    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 says:

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

  14. Akonde says:

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

  15. Juliette says:

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


  16. Samantha says:

    It made my PDF document all pixley

  17. hydra says:

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

  18. JC says:

    This tip worked for me, thanks!

  19. Sudhakar says:

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

  20. MR says:

    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 says:

    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 says:

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

  23. Spencer says:


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


  24. Bradley says:

    Thank you, Great tip. Worked really well!!

  25. Kenn Hong says:

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

  26. C. Hawkins says:

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

  27. Matt says:

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

  28. Biraj Naidoo says:

    Thanks for the great tip! Much appreciated.

  29. Mary Ann says:

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

  30. Carol Bartles says:

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

  31. Lama says:

    Great tip! this worked reduced my file from 7.8M to 1.1MB! So helpful

  32. Diane says:

    Thanks SO much!!!

  33. Jessica says:

    AMAZING! They’re a bit grainy but it worked. I needed to upload copies of my transcripts for a job posting, but the PDFs were too big. I’m a wiz with the fancier versions of Adobe you see in offices, but this was so helpful!

  34. Brook says:

    Awesome! My printer wouldn’t print my 4.5 mb pdf file but I was able to reduce it to 200 kb and it printed just fine! Thanks a lot.

  35. may says:

    Amazing! Thanks a bunch!
    Just a note that if you had anything highlighted on the PDF through Preview, they disappear after the file reduction!!

  36. anne says:

    Worked for me, thanks so much!!

  37. SK says:

    I needed to compress my file for a resume upload and this took my pdf from 3.3 MB to 410 KB. Thank you, thank you!

  38. Rod says:

    So how do you remove pages from a PDF? Sometimes I get manuals that are for several different versions of the same product. More often, I get manuals half of which are in Spanish, which I cannot read, and sometimes several different languages, only 2 of which I can read.

    I don’t want to waste the disk space and the extra time it takes to open a PDF that is at least twice as large as it needs to be.

  39. Fabio Buhr says:

    Thank you so much for this, very helpful and uses ready to use resources!

  40. Edgard Ade says:

    Original file: 315KB
    ‘Reduced’ file through ColorSync: 324KB.

    Not working for me on Yosemite.

  41. Toby Adobe says:

    This seems to work well.

    But I don’t understand why Acrobat bloats the files in the first place. I converted a 12.1 MB file to pdf format on a PC using Acrobat and got a 227 KB file. I did the same thing on a Mac using the trial version of Acrobat XI and got a 61 MB file. Using your method resulted in a 337 KB file.

    Needless to say, I’m not going to purchase Acrobat XI.


    • Wayne says:

      The larger the file the better the quality of the pictures. If you are going to print the file, which is what Acrobat was originally for, then the files should be big to get the best quality. So making a file smaller is for when you want someone else to view the file, but not print it. Adobe Acrobat Professional does have the ability to make the file smaller – just select ‘Save As… Reduced Size PDF’ from the menu.

      • Toby Adobe says:

        The Adobe folks got back to me. I originally created the pdf using “Create pdf from File” from the “File” menu in Acrobat, which increased the file size by a factor of 5 to 61 MB. They suggested you’re supposed to “Save as Adobe pdf” from the “Print” options within MS Word (“File” pull down menu). Doing so produced a 209 KB pdf file.

        I may yet purchase Acrobat for some of its other features though because of your method it’s not quite so essential. Thanks for your help.

  42. Pat says:

    So funny … you buy a Mac for thousands of Dollars or Euros … it makes PDFs of ridiculous size. All people not singing the praise of an OS that creates PDFs as a built-in feature notice that there is a flaw. You then find a work-around to reduce those bloated PDFs to acceptable size and all Mac users think this is a gift from heaven.

    WAKE UP, you Mac folks!

    How about you find a way to make your silly Mac OS produce reasonably sized PDFs in the first place? THAT would be the fix for the actual problem.

    Sorry, really no offense intended. I really appreciate this hint. Just would like people to realise that fixing the root cause would be even more helpful.

    • Wayne says:

      Pat, it’s important to be able to have large size pdf files as when pdf files are used for printing they need to be large. When you make them smaller it compresses the images so you do lose some quality. So yes, it’s handy to have them small, but it’s not desirable to have all pdfs small.

  43. MatW says:

    Thanks a LOT !! That works !

  44. neil cliff says:

    It’s really far simpler than that!

    Select document to be compressed. Then
    File-Export-Quartz Filter-(scroll down)-Reduce File Size-Save

    Make sure you title “Reduced File” and select where you want to save it to. Typically a 10:1 compression.

  45. mark says:

    one of the simplest , most straightforward and effective computer tips I’ve found.

    Thanks very much

  46. Jeremy says:

    This is amazing.. :) Just keep on clicking reduce file size and apply over and over again until you get your desired file size and save :P such a life saver :)

  47. milzo says:

    I have a Mac and these methods didn’t work, they made the pdf too blurry so I couldn’t read the writing! On another forum I found this site worked perfectly!
    Was free to use, reduced my file size from 3.5MB to 864kb

  48. Moinul says:

    Excellent, fantastic, marvelous…..

  49. Glenda says:

    Thank you so much. Worked perfectly.

  50. Margaret says:

    This is a great help thanks – I am quite a novice at this so when following your instructions the file size wouldn’t reduce, I tried applying a color filter to my pdfs. This worked very well, but the file size stubbornly won’t reduce. I did complete the application by clicking apply. Any ideas, please?

  51. Sergio says:


    It could help but there is no graduation in the compression.

    I have a PDF too big to be submitted to a website, and the “reduce file size” makes the file unreadable (no longer possible to read the text on the scanned image included in the PDF – the quality is too too low).
    It is not really helpfull.

  52. Wilfred says:

    Thanks, worked a treat!

  53. John says:

    Works a treat and FREE….Brilliant!!!!


  54. JOHN says:

    what a joke – the filter doesn’t recognize any selection, let alone “reduce file size” selection. Mac, in so many ways, is crap. such a simple, everyday thing that mac can’t even accomplish

  55. Scott says:

    I don’t know about older versions, but Preview 8 has an Export command in the File menu that gives you direct access to exactly the same filters that ColorSync uses to “reduce file size” of PDFs. Tested; it does exactly the same stuff. In my experience, the reduction filter doesn’t work very often and I’ve had it increase PDF file size more often than reduce it! Worth a try; I mean, it’s super easy. Another thing to try is to use the Print command and pick PDF. Again, I’ve had this increase the size, but one thing it does well: it gets rid of all versions that are saved into PDFs via Preview if you have Mac versioning turned on (so as you can Revert to… in the File menu if you save a mistake). Just print it to a different name if you want to keep all the version history of the original. I’m still looking for a free method to optimize PDFs on a Mac…

  56. Shira says:

    Thank you very much, this worked perfectly!

  57. Thierry says:

    This does not work with PDF containing high quality pictures. PDFOptim on App Store does the trick for 3$. Tried it and am very happy so far.

    @John, Windows 10 cannot handle it either, when trying to do anything with a PDF, the filesize doubles!!

  58. Richwoods says:


    Pages has an ‘Export To’ option under the ‘File’ menu which allows a new document to be created in PDF, Word, Plain Text, ePublisher or Pages ’09 format.

    This option allows you to select the quality, and hence size, of the exported document as ‘Good’, ‘Better’ or ‘Best’.

    I have just tested it on a 5.9 MB pages document of 9 pages including 65 jpg images, 83 pieces of separate text and 9 banner heading images. The size reductions and quality results were as follows:-

    • Good setting – 1.4 MB file – despite the name, image quality is very poor with quite bad blurring, text still okay but a little pixelated – not worth using this setting unless you are desperate.
    • Better setting – 2.5 MB file – image quality really quite good in general, a little bit of the jaggies appears on diagonal straight edges but not significant, text quite okay. Looks like a good compromise if your are looking to email PDFs.
    • Best setting – 5.0 MB file (not much of a reduction from 5.9) – image quality excellent, text good. This is the one to use if the larger file size is not a problem.

    This method has certainly helped me with this particular file, a furniture catalogue, hope it may be helpful to others.

    Running on iMac Retina 5K, 27-inch, Late 2014
    OS X El Capitan version 10.11.4 (15E65)
    3.5 GHz Intel Core i5
    16 GB 1600 MHz DDR3
    AMD Radeon R9 M290X 2048 MB

  59. Madusha says:

    Thank you.

  60. johan says:

    I battled with a multi page scan PDF that was too big for some users (18Mb) and eventually found a crowd called that uploaded it, I picked the mid-size compression and it came back about 10% of original size but still perfect quality for most users.

    they do a few other PDF things as well but I only tried the file size reduction

  61. Elisabeth says:

    I tried the reduce file size and it did help, but not much. It took a 1.8MB file down to 1.5MB. Is there a way to get them smaller?

    Also, I combine PDF’s in preview regularly and only occasionally have the bloat problem. Has anyone discovered the specific steps to avoid bloat as it doesn’t do it consistently?

    Thanks for the advice. Very helpful.

  62. Karambir says:

    A somewhat less complicated scenario is to choose “Live Update from Filter Inspector” in the ColorSync Utility. This provides a user interface where filters can be copied, modified, and renamed without having to disable security via csrutil.

  63. Tamsin Clarke says:

    I found that the compression in Preview doesn’t work well for scanned documents with text and/or figures as it indeed compresses the image too much and the text/figures become blurred. What worked for me was opening the scanned document in Preview, whether it was jpeg or pdf, then going to File/Take Screenshot/Selection, selecting the page, taking a screenshot, then again going to File and selecting Export as PDF for the screenshot document. That then brought my scanned documents down from around 10MB each to around 350KB and the figures were still clear and readable.

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