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I received a pdf of about 1Mb, with 6 pages. I opened each page, one at a time, in Illustrator, changed some text, then saved, so it saved back to the original PDF. After 6 pages of minor text changes, my PDF swelled to 23 Mb!

I have tried changing image compression to the minimum. Besides making the original, crisp images look terrible, it does little to the file size.

This makes no sense. I have tried saving without preserving editing capabilities, and all else I can find that might save bytes, including optimizing in Acrobat. The best I have been able to do is to get file size down to about 12 Mb with terrible image quality.

Addendum. I did not mark this as duplicate of another question because the edits I am making are so simple, there is no reason for increased file size, and the answers there do not help with my situation. The point one answer makes about the Audit feature, however, might prove helpful.

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  • Maybe try to decrase image resolution to 72 dpi ?
    – Marcin
    Feb 24, 2016 at 6:41
  • Is it embedding anything like fonts that you don't have or are the original pages images? If they are images then try OCR.
    – Paul
    Feb 24, 2016 at 8:48
  • have you tried opening in InDesign? There might be better options to optimize multipage PDFs than Illustrator..
    – Luciano
    Feb 24, 2016 at 9:04
  • Possible duplicate of How do I keep file sizes down when editing PDFs?
    – Luciano
    Feb 24, 2016 at 9:05
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    They've clearly already tried this, judging by what they say about "changing image compression to the minimum... making the original, crisp images look terrible". If raster image resolution was the problem, that wouldn't explain the increase in size from the original.
    – user56reinstatemonica8
    Feb 24, 2016 at 9:42

7 Answers 7

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When you Save a PDF with Illustrator, that is essentially an Illustrator document. It’s meant to be used as part of a PDF workflow, so it is saving as much information as it can.

If you want to make a shareable PDF with the smallest file size, choose File ▶ Print and print to PDF. That is a final PDF that is meant for distribution.

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I tried this using various settings for the PDF. From Preview (a mac PDF reader) I printed, then from the lower left menu selected Save As Adobe PDF. This presents options for the final PDF settings. Some of these (PDF/x 1b, e.g.) reduced to about half the original 23Mb. Selecting "Smallest Size" reduced way down to about 256kb, but hammered image quality. Just using the standard "Save as PDF...", which does not present PDF setting options, also just halved the file size. What seemed to work best for my purposes was saving as Adobe PDF and selecting "print quality" for the PDF setting. This reduced to 2.3Mb while preserving image quality (still way larger than the original's 1Mb with equal image quality). At least I can email this file.

I feel that this is not a particularly good answer, because it leaves open the question of what is in those extra 22Mb added by Illustrator. Another unanswered question is why using the Save as PDF... from Preview, with its PDF settings, creates files with different sizes than Acrobat does when using the same setting.

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  • Setting up my own pdf profile based on "[High Quality Print]" but increasing the downsampling on raster images to 500 for files larger than 750ppi produced very nice output with a relatively small file size.
    – geordie
    Jul 4, 2018 at 23:13
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Compatibility between different readers is one thing to try: maybe your new PDFs have broader compatibility than the original? This could cause ballooning file size if, for example, there's a complex effect like a gradient mesh that can be represented as one element in modern readers but needs to be broken into thousands of separate elements in older readers. I've had this problem when saving Gradient Mesh effects as EPS, never seen it for PDFs but it's possible.

If that's not it, Illustrator does sometimes bizarrely balloon file sizes. I've had PDFs that were stubbornly several megabytes in size even after deleting the entire contents of the PDF! I think Illustrator can sometimes find itself carrying dead weight that it's unaware of.

If all else fails, there are two brute force approaches to fixing bizarrely ballooned file sizes, which you could try individually or together:

  1. Create a new, blank document, with the same page settings, and copy and paste the contents over. Hopefully this will keep the artwork and leave behind the cruft.
  2. Place all the different PDFs into another application (ideally InDesign, one page per page, but you could maybe use Illustrator), then save as one PDF from there. The master application should apply its own PDF settings, hopefully cheerfully annoying all the cruft in the placed PDFs.

Assuming the problem is a load of dead weight behind the PDF, these could trick Adobe into ignoring that dead weight and just looking at the actual artwork.

Do these from the original, pre-inflation PDF, in case an earlier use of unticking the "Preserve editting capabilities" alongside generous compatibility settings or similar caused an effect to be broken into thousands of component parts irreversibly.

If even this doesn't work, chances are Illustrator is breaking something simple into something complicated the moment you first open the PDF. If you open then do nothing but save as .ai, is that huge too?

If the text edits aren't simple enough to do in something like Acrobat, you might be able to place the PDF in illustrator (therefore not converting it into editable Illustrator format, therefore not expanding whatever effect is causing the ballooning file size), then super-impose your new text over the top.

If super-imposing isn't possible, if you've got Acrobat or similar, you could delete the incorrect text elements completely in that, save, then place into Illustrator and add new text over the top in Illustrator.

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  • user568458, I tried inDesign, because I thought it would be able to handle multiple pages, unlike Illustrator. One guess is that since each of the 6 pages needs to be opened and saved individually, many of the bytes added by Illustrator are redundant. Unfortunately, inDesign will not open tis PDF.
    – stevero
    Feb 25, 2016 at 19:55
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    No, you don't open the PDF in InDesign, you build the new PDF by creating a blank document in InDesign then adding the PDFs from Illustrator or whatever with file > place
    – user56reinstatemonica8
    Mar 1, 2016 at 17:54
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I don't know why you are using Adobe Illustrator as a text editor instead of Adobe Acrobat. Adobe Acrobat PDF creator would be a better tool to use for that purpose. If you don't own Adobe Acrobat PDF creator, you can also try a different way of reducing the file size of the PDF using free software.

I can't do anything about the 12MB output file size, because my way of doing it results in an output file that is also about half the size of the original input file. However I can do something to improve the terrible image quality of the output file. I am using a free, open source cross-platform program called Ghostscript (Windows/Mac/Linux) in a Linux OS.

Open a Linux terminal and type: 

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

output.pdf and input.pdf are names that I am using to denote the input and output files, and they can be changed to different file names which contain no blank characters.

The images in the output file will look OK, but expect to lose some razzle dazzle sharpness in small details. There are several options to choose from in Ghostscript to produce output files of varying quality.

  • /screen – selects low-resolution output similar to the Acrobat Distiller "Screen Optimized" setting.
  • /ebook – selects medium-resolution output similar to the Acrobat Distiller "eBook" setting.
  • /printer – selects output similar to the Acrobat Distiller "Print Optimized" setting.
  • /prepress – selects output similar to Acrobat Distiller "Prepress Optimized" setting.
  • /default – selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.
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  • I use Illustrator because its editing tools are much easier to use, at least for me. I quite dislike editing with Acrobat. Since both are Adobe tools, I assumed either would be acceptable. Regardless of whether this assumption is reasonable (one could argue that this is not really what Illustrator or best at), a 23-fold increase in file size, without any increase in quality, quantity, features, etc, is certainly not reasonable.
    – stevero
    Feb 25, 2016 at 19:37
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    If Acrobat was as easy to use as Illustrator, then Adobe probably wouldn't have called their product Acrobat.
    – karel
    Feb 25, 2016 at 19:39
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Try File > Save As… > Reduced Size PDF (CS6), or on older versions of Acrobat it may be under the Document > Reduce File Size. Sometimes this works wonders, other times not so much.

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  • A thread in this link says Adobe Acrobat 9 has the Reduced Size feature that you mentioned, and that it is able to make smaller sized files than Optimized PDF does in Acrobat 10. Unfortunately I was not able to determine from reading the thread if the author was talking about the free Adobe Acrobat Reader or Adobe Acrobat Pro version. The most optimistic result to hope for is that the free Adobe Reader 9 has this feature and that it works better than Optimized PDF does.
    – karel
    Feb 25, 2016 at 19:44
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Save your file as PDF, then choose High quality Print and unmark everything (including and especially Preserve Illustrator editing Capabilities) except Optimize for Fast Web view.

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  • Please add an screenshot showing what you mean. Welcome to GD.SE!
    – Mensch
    May 16, 2016 at 22:18
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When you Save a PDF with Illustrator, that is essentially an Illustrator document. It’s meant to be used as part of a PDF workflow, so it is saving as much information as it can.

Precisely.

Uncheck "Preserve Illustrator Editing Capabilities" when saving as PDF, that should do the trick.

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  • As I said in my initial question, " I have tried saving without preserving editing capabilities". Perhaps this was not clear enough. The best answer is the one from @SimonWhite.
    – stevero
    Nov 28, 2017 at 23:51

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