Compress PDF files


  1. Posts : 621
    Windows 10 Pro 19042 x64
       #1

    Compress PDF files


    Hello,
    Have lot of pdf files on my disk, I have read about software to compress these files.
    1. Is there some program (free if possible) to do it ?
    2. Is the compression effective (in percent), so to start installing the program ?
    3. After compression, are the files still readable ?
    Answers will be appreciated
    Thanks
    Motim
      My Computer


  2. Posts : 73
    win 10
       #2

    Its possible to compress pdf's I assumed PDF' files are designed to use the least amount of space possible there are lots of "FREE" services online most are average. personally i wouldn't use them, all tho i have used some to convert files
      My Computer


  3. Posts : 1,621
    Windows 10 Home
       #3

    Google may be our friend:
    Can PDF files be compressed? - Google Search
    I'm not sure which of the URLs in that search will be useful to you.
      My Computer


  4. Posts : 31,468
    10 Home x64 (22H2) (10 Pro on 2nd pc)
       #4

    Motim said:
    Have lot of pdf files on my disk, I have read about software to compress these files.
    1. Is there some program (free if possible) to do it ?
    2. Is the compression effective (in percent), so to start installing the program ?
    3. After compression, are the files still readable ?
    Do you want to compress without loosing any quality, or would you accept a lower quality and/or resolution?

    Images in pdfs can be saved in a lossless form or use jpeg compression, for jpegs the level of compression can be increased at the cost of some loss of quality. The image resolution could also be reduced to save space. Any compression software would likely use these techniques to reduce the size of the file. Whether you notice the difference would depend on how heavily the compression was applied.

    For compression that leaves the original file untouched there are two options in Windows itself - ntfs file compression or 'send to a compressed (zipped) folder'. If you have Libre Office or similar you already have software that can open a pdf for editing and export it in a lower quality form.

    As an experiment I downloaded an illustrated manual in pdf form. The original file size was 17.2MB.

    ntfs compression:
    Right-click on file, select properties, click the 'Advanced...' button and tick 'compress contents to save disk space'.
    After compression File Explorer still shows the original file size, but its Properties shows 'size on disk: 16.4MB'. The data in the file is unaltered and the file can be opened as normal.

    Send to zipped folder:
    The zip folder produced was 14.7MB. Windows can open a zipped folder like any other folder so you can still easily read the pdf in its original form.

    Reduced resolution and increased compression with Libre Office:
    Opened in Libre Office Writer and exported to pdf, image resolution reduced from 300dpi to 150dpi, jpeg compression quality lowered to 33%. The exported pdf was 5.32MB. The loss of image quality was unnoticeable but some formatting changes were introduced, particularly in the alignment of the table of chapters. Such problems may be found in other pdf compression software, so beware.
      My Computers


  5. Posts : 621
    Windows 10 Pro 19042 x64
    Thread Starter
       #5

    Hello,
    Thanks for the answer.
    I tried the "ntfs compression" technique, the pdf file was almost not changed in size, I will try to 'zip' all pdf files and see what I get.
    2. For the first time I got in my mail a private message from the forum, it was very strange for me. After solving the message, my answer to this is thanks for the message, but I say thanks-no.
    THanks.
    Motim
      My Computer


  6. Posts : 31,468
    10 Home x64 (22H2) (10 Pro on 2nd pc)
       #6

    Motim said:
    I tried the "ntfs compression" technique, the pdf file was almost not changed in size,
    File Explorer will still show the original size of the file. To see how much it has shrunk, right-click on it and select 'Properties'. This shows two sizes, the important one is the 'Size on disk' which should now be smaller that the file size. How much smaller depends on how easy it is to compress that pdf, some will compress more than others.
      My Computers


  7. Posts : 2,068
    Windows 10 Pro
       #7

    PDF's are usually in a compressed format to start with. I don't think most are going to compress well, if at all.
      My Computers


  8. Posts : 13,896
    Win10 Version 22H2 Pro and Home, Win11 Pro and Home
       #8

    Even though a compressed file into a .zip format will not show much shrinkage it is important to me as some forums or sites allow only certain formats and .zip is pretty much universal, useful to meet those requirements.
      My Computers


 

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