I have a 72.9 MB PDF file that I need to shrink to 500 KB or below.

The file was a JPEG image that I had scanned and then converted to PDF.

  • 1
    it depends on what consumes the space...need a lot more information. compressing image space could help, but if you're trying a large file heap spray, that won't work. seriously need more info. Commented Mar 16, 2012 at 17:14
  • 1
    convert it to DjVu, instead trying to reduce to impossible sized PDF (according source)
    – zetah
    Commented Mar 16, 2012 at 17:22
  • 2
    It only seems to help filesize a little bit, but pdfopt has a simple syntax and improves loading and page-turning speed in the iPad era. :-) Commented May 31, 2012 at 0:53
  • 2
    PDF to PS is not effective in scanned PDF file, I try to convert 56 MB pdf into ps file but ps file convert into 1.3 GB and again ps2pdf is converted in 45 MB file
    – user124118
    Commented Jan 18, 2013 at 5:32
  • Please see this related Q&A for a number of GUI front ends to ghostscript that should make the process of reducing PDF filesizes easier. Commented Apr 11, 2013 at 21:58

25 Answers 25


Use the following Ghostscript command:

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

Summary of -dPDFSETTINGS:

  • -dPDFSETTINGS=/screen lower quality, smaller size. (72 dpi)
  • -dPDFSETTINGS=/ebook for better quality, but slightly larger pdfs. (150 dpi)
  • -dPDFSETTINGS=/prepress output similar to Acrobat Distiller "Prepress Optimized" setting (300 dpi)
  • -dPDFSETTINGS=/printer selects output similar to the Acrobat Distiller "Print Optimized" setting (300 dpi)
  • -dPDFSETTINGS=/default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file


Controls and features specific to PostScript and PDF input


Presets the "distiller parameters" to one of four predefined settings:

  • /screen selects low-resolution output similar to the Acrobat Distiller (up to version X) "Screen Optimized" setting.
  • /ebook selects medium-resolution output similar to the Acrobat Distiller (up to version X) "eBook" setting.
  • /printer selects output similar to the Acrobat Distiller "Print Optimized" (up to version X) setting.
  • /prepress selects output similar to Acrobat Distiller "Prepress Optimized" (up to version X) setting.
  • /default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.

The exact settings for each of these, including their DPI values, are shown in the dozens of options in this table.

  • 2
    One can also make a Nautilus script to access this function for every file.
    – Sina
    Commented May 7, 2013 at 15:51
  • 23
    This should be the accepted answer. ghostscript is the PDF, XPS and PS implementation for unices and can do basically everything delivering best quality...
    – dom0
    Commented Oct 2, 2013 at 17:27
  • 9
    @Sina: There is actually a Nautilus Script with a simple Zenity-based GUI that utilizes this gs command with all its quality-level options: launchpad.net/compress-pdf
    – Sadi
    Commented Oct 25, 2013 at 11:47
  • 56
    This is the right answer for this question (compressing a pdf that is mostly bitmap data). I found that the screen setting was too low quality for me, but ebook worked well, cutting a 33Mb scan-based PDF down to 3.6Mb, and keeping it very readable. Other options for the -dPDFSETTINGS option are listed here: milan.kupcevic.net/ghostscript-ps-pdf, and it might be a good idea to include them in this answer.
    – naught101
    Commented Dec 2, 2014 at 1:13
  • 4
    on 17.10 it made 42 mb pdf to 127 mb :( Commented Oct 23, 2017 at 3:24

My favorite way to do this is to convert the PDF to PostScript and back. It does not always work, though, but when it works the results are nice:

ps2pdf input.pdf output.pdf

This also directly works on PDFs, as suggested in the comments.

Some users also report more success when using the ebook settings as follows:

ps2pdf -dPDFSETTINGS=/ebook input.pdf output.pdf
  • 22
    Despite the fact that this one approach became my favorite solution to compress pdf files, it breaks up url links the document may have (which does not happen with @Michael D's approach). Apart from that, awesomeness is all I can think of running this snippet! (:
    – Rubens
    Commented Dec 6, 2013 at 11:01
  • 4
    This bypasses password protection...just sayin'
    – j-i-l
    Commented Jan 6, 2015 at 20:28
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    ps2pdf will take pdfs as inputs, so you can do this in one step: ps2pdf intput.pdf output.pdf
    – frabjous
    Commented Sep 1, 2016 at 19:19
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    @don.joey can't understand why, since just extends your answer. Main thing here: ps2pdf also use ghostscript, so you can use things like -dPDFSETTINGS=/ebook. Commented Mar 23, 2017 at 20:26
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    It didn’t work (84 MB→82 MB), but ps2pdf -dPDFSETTING=/ebook in.pdf out.pdf , as suggested by @PabloBianchi leads to 272 kB ! Thanks a lot ! Commented Mar 17, 2019 at 17:32

aking1012 is right. With more information regarding possible embedded images, hyperlinks etc.. it would be much more easier to answer this question!

Here are a couple of script and command-line solutions. Use as you see fit.

  • 28
    Thank you very much for your suggestions, the ghostscript shell worked wonders and shrank it down to 460KB :)
    – tamimym
    Commented Mar 16, 2012 at 19:56
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    I recommend you shrinkpdf.sh script, you can customize the code to use the ppi value you want (72 by default) and reach exactly the filesize you need to sacrifice the least quality. This made me able to upload a scanned document of 11 MB with a max. size of 3 MB without losing a lot of quality.
    – Severo Raz
    Commented Apr 9, 2016 at 22:18
  • 9
    shrinkpdf works great!
    – AmanicA
    Commented Feb 22, 2017 at 22:14
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    Where is the ghostscript shell that the OP is referring to askubuntu.com/questions/113544/…?
    – user13107
    Commented Mar 5, 2018 at 6:44
  • 1
    @user13107 It is this answer - askubuntu.com/a/256449/171427 Commented Nov 15, 2019 at 17:21

If you have a pdf with scanned images, you can use convert (ImageMagick) to create a pdf with jpeg compression (You can use this method on any pdf, but you'll loose all text informations).

For example:

convert -density 200x200 -quality 60 -compress jpeg input.pdf output.pdf

Adjust the parameters to your needs

  • -density: the pixel density in dpi (e.g. 100x100). Higher pixel densities increase quality and size
  • -quality: the compression ratio. For jpg it is between 1 to 100 with 100 the best quality, but lowest compression
  • -compress: the compression algorithm. jpeg compression might not be the best choice due to compression artifacts. You have the choice between BZip, Fax, Group4, JPEG, JPEG2000, Lossless, LZW, RLE or Zip as alternate compression methods (some only allow b/w images).

I was able to achieve great compression ratios for scanned/photographed documents (depending on the settings). Depending on the document source, you might want to reduce the color depth (-depth argument).

  • 4
    For a scanned document where the text is what you are interested in rather then the images and preserving depth isn't an issue, jpeg compression is not a good idea because the artifacts tend to be extremely noticeable. If you use pdfimages input.pdf pages to extract pbm files, then you can do something like: for page in *.pbm; do convert $page -compress Group4 -type bilevel TIFF:- | convert - output.pdf. Any OCR will be lost so I usually then do pdfsandwich output.pdf, which seems to reduce file size even further.
    – Brian Z
    Commented May 4, 2015 at 11:57
  • 1
    @BrianZ sure jpeg compression isn't always the best choice, but for me it was the best approach for mixed type documents. I added some informations about other compression methods to the answer.
    – someonr
    Commented May 6, 2015 at 23:43
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    This method ultimately uses gs behind the scenes.
    – alfC
    Commented Jun 12, 2015 at 4:55
  • 2
    I had to use double dash for the options to run the command --density --quality --compress vs -density -quality -compress.
    – Rotareti
    Commented Nov 10, 2016 at 18:22
  • 2
    If image qaulity is not the highest concern (and you just want to get that dang email attachment small enough to be sent) one might add -resize 50% too, change percentage depending on how much DPI was used while scanning
    – chrki
    Commented Jan 11, 2017 at 0:45

I needed to downsize a PDF that contained full color scans of a document. Each of my pages was a full color image as far as the file was concerned. They were images of pages containing text and images, but they were created by scanning to an image.

I used a combination of the below ghostscript command and one from another thread.

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dDownsampleColorImages=true \
-dColorImageResolution=150 -dNOPAUSE  -dBATCH -sOutputFile=output.pdf input.pdf

This reduced the image resolution to 150dpi, cutting my file size in half. Looking at the document, there was almost no noticeable loss of image quality. The text is still perfectly readable on my 2012 Nexus7.

  • 7
    +1 for down sampling images but keeping text as vectors. Made a huge difference in side without making my text pixelated. Commented Dec 8, 2014 at 8:34
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    Fantastic that one can tune the resolution with this command - this gave me better results than just using dPDFSETTINGS=\screen
    – exchange
    Commented May 13, 2019 at 10:04
  • See also: stackoverflow.com/questions/9497120/…
    – sanmai
    Commented Aug 12, 2020 at 8:44
  • 1
    +1 for the option that allows you to specify the exact resolution. Useful when you have a scanned pdf (all raster) and want to reduce the size keeping the file still readable. Commented Nov 18, 2021 at 9:14

Here is a script for rewriting scanned pdfs:


gs  -q -dNOPAUSE -dBATCH -dSAFER \
    -sDEVICE=pdfwrite \
    -dCompatibilityLevel=1.3 \
    -dPDFSETTINGS=/screen \
    -dEmbedAllFonts=true \
    -dSubsetFonts=true \
    -dColorImageDownsampleType=/Bicubic \
    -dColorImageResolution=72 \
    -dGrayImageDownsampleType=/Bicubic \
    -dGrayImageResolution=72 \
    -dMonoImageDownsampleType=/Bicubic \
    -dMonoImageResolution=72 \
    -sOutputFile=out.pdf \

You could customise it a bit to make it more reusable but if you only have one pdf, you could just replace $1 with your pdf filename and bung it in a terminal.

  • 1
    Works a treat, thanks Oli. You've answered pretty much everything I've asked on here so far :-D
    – Rob Cowell
    Commented Sep 1, 2010 at 8:15
  • This is a good answer but in my case at least it takes a lot of time to convert a somewhat large (>10Mb) PDF file (more than a minute).
    – Gabriel
    Commented Jun 12, 2013 at 19:20
  • 1
    I'm not sure what happens, but a 30 MB PDF results a 68 MB file. Instead of reducing, it enlarges. Same output if using directly ps2pdf as stated in next answer. Commented Jun 23, 2013 at 18:08
  • 1
    @EdVillegas The only thing I can think of (to explain that sort of increase) is that the images are of a lower resolution than the ones being generated (72dpi). Or somehow embedding the fonts is sucking in all the fonts.
    – Oli
    Commented Jun 25, 2013 at 7:31
  • 1
    use pdfimages -list file.pdf to see the native images resolution.
    – vstepaniuk
    Commented May 21, 2020 at 10:53
  1. I use LibreOffice Draw to open the pdf.
  2. I then "export as pdf"
  3. And set "jpeg compression quality" to 50% and "image resolution" to 150 dpi

This will have a good result.

  • 4
    Worst possible solution to the problem! It totally messed my file up!
    – user783132
    Commented Jan 15, 2018 at 16:31
  • 4
    For my this solutions is the best, it is only necessary to configure it depends on what one wants to do. Working for my with this settings "jpeg compression quality" to 83% and "image resolution" to 150 dpi Commented Jun 3, 2020 at 14:39
  • This worked for me
    – Raj
    Commented Nov 12, 2021 at 6:50
  • I'd rather set 300 DPI and 50% compression, but it depends on the content of the pdf.
    – france1
    Commented Jan 24, 2023 at 20:35

I usually use ps2pdf to do this (easier syntax), something like this:

ps2pdf -dPDFSETTINGS=/ebook BiggerPdf SmallerPDF

I use the following python script to reduce the size of all the pdf files in a dir in a production server (8.04). So it should work.


import os

for fich in os.listdir('.'):
        if fich[-3:]=="pdf":
                os.system("ps2pdf -dPDFSETTINGS=/ebook %s reduc/%s" % (fich,fich))
  • Thanks for the alternative solution. I tried Oli's first and it gave me the result I needed, but I will keep this one for future reference too.
    – Rob Cowell
    Commented Sep 1, 2010 at 8:17
  • 3
    -dPDFSETTINGS=/printer option do 50% resize. ebook do 90% resize.
    – neouyghur
    Commented Apr 13, 2018 at 6:08
  • Thank you! I could reduce a PDF from 67.7 MB to 18.4 MB with the first syntax.
    – Vitor
    Commented May 15 at 14:46

Best for me was

convert -compress Zip -density 150x150 input.pdf output.pdf

Other ways:

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

### pdf2ps && ps2pdf
pdf2ps input.pdf output.ps && ps2pdf output.ps output.pdf

### Webservice


  • 1
    Great solution. Easy to remember and it brought my pdf from 32 to 3.5 MB without sensible loss in readability. Commented Mar 17, 2018 at 9:57
  • I liked the second way pdf2ps input.pdf temp.ps && ps2pdf14 temp.ps output.pdf && rm temp.ps
    – McPeppr
    Commented Nov 6, 2018 at 21:16

For my other, pdfsizeopt-based answer, see here.

Referencing this answer and this answer, and after trying a bunch of the answers here, and doing a bunch of research and experimenting, I've come up with the following. Note that I've removed the -dCompatibilityLevel=1.4 part of the command used in some other answers here (including the most-upvoted answer) because this table indicates that 1.5 or 1.7 are automatically used for this setting today (27 Dec. 2020), and there's no need to override those values.

Use Ghostscript (gs) to compress input.pdf into output.pdf

3 Main levels of compression:
Note: you may also add -dQUIET to suppress all output to stdout. See: https://ghostscript.readthedocs.io/en/latest/Use.html.

  1. Low compression: 300 dpi (large file size)
    gs -sDEVICE=pdfwrite -dPDFSETTINGS=/printer -dNOPAUSE -dBATCH \
    -sOutputFile=output.pdf input.pdf
  2. [BEST in my testing] Medium compression (recommended): 150 dpi (medium file size)
    gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook   -dNOPAUSE -dBATCH \
    -sOutputFile=output.pdf input.pdf
  3. High compression: 72 dpi (small file size--may produce grainy or unreadable results in some cases, so try it and give it a shot)
    gs -sDEVICE=pdfwrite -dPDFSETTINGS=/screen  -dNOPAUSE -dBATCH \
    -sOutputFile=output.pdf input.pdf

You can also add time in front of the command to see how long it takes (this works with any Linux command). Sample output:

$ time gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -sOutputFile=out.pdf in.pdf
GPL Ghostscript 9.50 (2019-10-15)
Copyright (C) 2019 Artifex Software, Inc.  All rights reserved.
This software is supplied under the GNU AGPLv3 and comes with NO WARRANTY:
see the file COPYING for details.
Processing pages 1 through 15.
Page 1
Loading NimbusSans-Regular font from /usr/share/ghostscript/9.50/Resource/Font/NimbusSans-Regular... 5205104 3852122 2872760 1487237 3 done.
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15

real    0m1.326s
user    0m1.142s
sys     0m0.048s

If you add -dQUIET to the command, none of the Ghostscript output is shown, and you get this (when using time in front):

$ time gs -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -dQUIET -sOutputFile=out.pdf in.pdf

real    0m1.018s
user    0m0.976s
sys     0m0.040s

You can also use ps2pdf, which is a wrapper around gs, and produces very similar, but not exactly identical, results. I prefer to just use gs directly, as shown above, however.

  1. Low compression: 300 dpi (large file size)
    ps2pdf -dPDFSETTINGS=/printer input.pdf output.pdf
  2. Medium compression (recommended): 150 dpi (medium file size)
    ps2pdf -dPDFSETTINGS=/ebook   input.pdf output.pdf
  3. High compression: 72 dpi (small file size--may produce grainy or unreadable results in some cases, so try it and give it a shot)
    ps2pdf -dPDFSETTINGS=/screen  input.pdf output.pdf

PDF Compression Tests

Testing the gs commands above on output from my pdf2searchablepdf script here, I see the following:

  1. Low compression: has no significant effect since my script already produces 300 dpi output PDFs. So, a 3.8 MB 3 pg input PDF results in an output PDF of ~3.8MB.
  2. [BEST] Medium compression: compresses the file nicely! A 3.8 MB 3 pg input PDF results in an output PDF of ~0.95MB.
  3. High compression: may be too much. A 3.8 MB 3 pg input PDF results in an output PDF of ~0.37MB, BUT in my particular test is completely unreadable, since the input PDF was already of somewhat poor resolution to begin with. If you begin with a high quality/high resolution input PDF, you may have much better, readable results.

Ghostscript (gs) Documentation:

For all -d ("define") PDFSETTINGS available, see here: https://ghostscript.readthedocs.io/en/latest/VectorDevices.html#controls-and-features-specific-to-postscript-and-pdf-input. I have quoted that section below, except that I've added the DPI values for each setting in bold, as taken from this table here. You can refer to that table to see the dozens of lower-level settings chosen by gs for each PDFSETTINGS option.

Controls and features specific to PostScript and PDF input


Presets the "distiller parameters" to one of four predefined settings:

  • /screen (72 dpi) selects low-resolution output similar to the Acrobat Distiller (up to version X) "Screen Optimized" setting.
  • /ebook (150 dpi) selects medium-resolution output similar to the Acrobat Distiller (up to version X) "eBook" setting.
  • /printer (300 dpi) selects output similar to the Acrobat Distiller "Print Optimized" (up to version X) setting.
  • /prepress (300 dpi) selects output similar to Acrobat Distiller "Prepress Optimized" (up to version X) setting.
  • /default (72 dpi) selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.

You can also see definitions for various options on this page: https://ghostscript.readthedocs.io/en/latest/Use.html:

Disables the prompt and pause at the end of each page. Normally one should use this (along with -dBATCH) when producing output on a printer or to a file; it also may be desirable for applications where another program is "driving" Ghostscript.

Causes Ghostscript to exit after processing all files named on the command line, rather than going into an interactive loop reading PostScript commands. Equivalent to putting -c quit at the end of the command line.

Suppresses routine information comments on standard output. This is currently necessary when redirecting device output to standard output.


I strongly recommend pdfsizeopt.

It is much more efficient in terms of size reduction than any of the previous CLI and GUI software that I have tried (including convert, gs, pdftk, etc.) — although possibly slower with pngout activated —, and does not have some of their issues (no heavily pixelated/degraded images, no loss of metadata such as table of contents, etc.).

Now, if you need to attain a certain size whatever the consequences (inc. degrading images to a point of unreadability), it might not be the tool you need, but as an always-working go-to solution, to reduce unnecessary big sizes in PDFs without loosing in readability, information and acceptable image quality, I think it is the best option. (Note: I tend to use it after having first done a vectorization-OCR in Adobe Acrobat [the function used to be called "CleanScan"], which can have a dramatical size impact on some scanned text documents.)

I recommend the generic Unix install:

  1. Install all required dependencies:
  2. Download and install the executable:
    curl -L -o pdfsizeopt.single https://raw.githubusercontent.com/pts/pdfsizeopt/master/pdfsizeopt.single
    chmod +x pdfsizeopt.single
    cp pdfsizeopt.single /usr/local/bin/pdfsizeopt


pdfsizeopt original.pdf [compressed.pdf]

Note: for Mac users finding this post (or Linuxbrew users), there is a Homebrew install formula:

brew install --HEAD pts/utils/pdfsizeopt
  • 2
    what MARVELOUS GEM of a software! Thank you very much for reccomending this :-)
    – luca76
    Commented Nov 13, 2019 at 13:39
  • No luck. Running pdfsizeopt on a 3.8 MB 3pg 300 DPI output PDF file from my pdf2searchablepdf script, the size remained 3.8 MB (it got smaller by a few KB is all). Commented Dec 27, 2020 at 3:51
  • 1
    @GabrielStaples: pdfsizeopt will not always reduce filesize significantly. If that is what I'm after (strongest reduction), I use other software (e.g., PDF Squeezer) that reduces image quality more drastically. pdfsizeopt is my default CLI solution for batch PDF resizing.
    – iNyar
    Commented Mar 4, 2021 at 18:33
  • 1
    For anyone struggling to install the jbig2, pngout, and sam2p dependencies, I've detailed full installation instructions for those in my answer here. Commented May 2, 2023 at 23:27

I just encountered this problem myself. If using simple scan, select text mode for low resolution scans and you won't need to worry about the command line stuff. Just saying.

  • 1
    This is the single answer in this thread that solved my problem. I downplayed Simplescan, but it really was the answer for me, instead of fighting against Xsane in what seemed to be an endless agony.
    – versvs
    Commented Aug 31, 2015 at 16:03

Control the compression quality:

INPUT=$1; shift
OUTPUT=$1; shift

# Image Compression Quality
# Quality HSamples VSamples QFactor
# Minimum [2 1 1 2] [2 1 1 2] 2.40
# Low     [2 1 1 2] [2 1 1 2] 1.30
# Medium  [2 1 1 2] [2 1 1 2] 0.76
# High    [1 1 1 1] [1 1 1 1] 0.40
# Maximum [1 1 1 1] [1 1 1 1] 0.15 

${GS_BIN} -dBATCH -dSAFER -DNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=${OUTPUT} -c "<< /ColorImageDict << /QFactor ${QFACTOR} /Blend 1 /HSample [1 1 1 1] /VSample [1 1 1 1] >> >> setdistillerparams" -f ${INPUT}
  • ...so both INPUT and OUTPUT are the same argument? You might want to add usage guidelines. Commented Apr 2, 2016 at 11:46
  • 2
    Note the shift. First parameter is input file, second is the output file and rest of the parameters will be passed to gs as is. Commented May 13, 2016 at 12:53
  • I think you want /HSamples and /VSamples, not /HSample and /VSample. See e.g. ps2pdf docs or the PostScript language reference manual. Also perhaps worth noting that the allowed QFactor range is 0 to 1,000,000 and lower values produce higher quality.
    – Pont
    Commented Aug 2, 2017 at 8:31

For me the gs screen option was too bad, and the ebook one too big.

My original document contained text as colour and black and white images (depending on the page).

The best solution I did come up has been:

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dDownsampleColorImages=true -dDownsampleGrayImages=true -dDownsampleMonoImages=true -dColorImageResolution=130 -dGrayImageResolution=130 -dMonoImageResolution=130 -r130 -dNOPAUSE  -dBATCH -sOutputFile=output_lr.pdf input.pdf

Note that the compression level is not linear.. if I was specifying 135 it didn't compressed, I did find 130 to be (in my case) the maximum resolution that achieves a compression.

  • 1
    The fact that specifying a target resolution of 135 didn’t reduce the file size is likely because of the ColorImageDownsampleThreshold option (and the other two for gray and monochrome), which defaults to 1.5 and tells ghostscript not to reduce the resolution of images whose resolution is not at least 1.5 times the target resolution. Your PDF probably contained images at 200 dpi, for which a target resolution of 135 dpi is a 1.48x decrease, but 130 dpi a 1.54x decrease. That’s probably because Commented May 26, 2023 at 6:47

Since this link was first for me when I searched in Google, I thought I'd add one more possibility. None of the above solutions was working for me on a pdf exported from Inkscape (15 mb), but I was at last able to shrink it down to 1 mb by opening it in GIMP, and exporting as pdf again.

Another option that came close (but text was a little fuzzy) was ImageMagick's convert utility:

convert -compress Zip input.pdf output.pdf
  • 1
    I guess this is what you meant by "a little fuzzy", but just to clarify, convert -compress Zip appeared to rasterise all vectors.
    – Sparhawk
    Commented Feb 22, 2015 at 3:39

I was facing the same problem, and was glad to find this thread. Specifically I had a pdf generated from scanned images, and needed to reduce its byte size by a factor of 6.

Unfortunately, none of the solutions above worked :(. Then I realized that somewhere in the scanner->jpeg->pdf process the size of the page had gotten bloated by a factor of aprx 4. The documents I scanned were all Letter sized, but the pdf had size of

identify -verbose doc_orig.pdf | grep "Print size"
 Print size: 35.4167x48.7222

I got the desired results finally with a "convert" command that did both resizing as well as compression steps in one:

convert -density 135x135 -quality 70 -compress jpeg -resize 22.588% doc_orig.pdf doc_lowres.pdf

Note that doc_orig had density of 72x72 dpi.

  • Your answer is a life saver, Kalpit. I was faced with the same problem, and nothing else was even making a dent in the file size. By resizing my pages, I went from 40MB to 2MB. Hurray! Commented Sep 12, 2020 at 15:38

In the end I wrote my own bash script to solve this, it uses mogrify, convert and gs to extract pdf pages as png, resize them, convert them to 1-bit bmp and then rebuild them as pdf. File size reduction can be over 90%. Available at http://www.timedicer.co.uk/programs/help/pdf-compress.sh.php.


If converting to djvu would also be ok and if no colors are involved, you could try the following:

Convert the pdf to jpg files using pdfimages -j

If you get pbm files instead, you should do the intermediate step:

for FILENAME in $(ls *.pbm); do convert $FILENAME ${FILENAME%.*}.jpg ;done

The convert command is from the imagemagick package.

Then use scantailor to make tif's out of it.

In a last step you go to scantailors out direcory (where the tif's are located) and apply djvubind to that directory.

This should reduce the filesize drastically without big quality loss of the text. If you want finer control over the ocr-backend, you may try djvubind --no-ocr and use ocrodjvu to add the ocr layer afterwards.

If you have color's in your document things get a bit more complicated. Instead of djvubind you could use didjvu and in scantailor you have to change to mixed mode and select sometimes color-images manually.


load image or even pdf file into inkscape.

From inkscape: Save in vector format (as the native .svg).

Import vector files into scribus, edit layout and export/save as .pdf from there


You can try this :

$ time pdftk myFile.pdf output myFile__SMALLER.pdf compress
GC Warning: Repeated allocation of very large block (appr. size 16764928):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 8384512):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 11837440):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 8384512):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 33525760):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 7254016):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 34041856):
    May lead to memory leak and poor performance.
GC Warning: Repeated allocation of very large block (appr. size 33525760):
    May lead to memory leak and poor performance.

real    0m23.677s
user    0m23.142s
sys     0m0.540s
$ du myFile*.pdf
108M    myFile.pdf
74M     myFile__SMALLER.pdf

It is faster than gs but compresses upto 30% in this case for a 107.5MiB input file.

  • No luck for me. On Ubuntu 20.04 on a searchable output PDF file from my pdf2searchablepdf program, the output file was identical in size to the input file. Commented Dec 24, 2020 at 11:20

I use this zsh function for compressing scanned documents:

pdf-compress-gray () {
    local input="${1}"
    local out="${2:-${input:r}_cg.pdf}"
    local dpi="${pdf_compress_gray_dpi:-90}"

    gs -q -dNOPAUSE -dBATCH -dSAFER -sProcessColorModel=DeviceGray -sColorConversionStrategy=Gray -dDownsampleColorImages=true -dOverrideICC -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dColorImageDownsampleType=/Bicubic -dColorImageResolution=$dpi -dGrayImageDownsampleType=/Bicubic -dGrayImageResolution=$dpi -dMonoImageDownsampleType=/Bicubic -dMonoImageResolution=$dpi -sOutputFile="$out" "$input"


[pdf_compress_gray_dpi=100] pdf-compress-gray input.pdf [output.pdf]

I normally simply use

gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -dPDFSETTINGS=/printer \
   -sOutputFile=output.pdf input.pdf

I went through many questions one how to reduce the size of a pdf on AskUbuntu, Stack Overflow and Unix & Linux SE and I wondered what all those options proposed in the answers meant.

Some are Interaction-related parameters:


Some are Device and output selection parameters:


Some are Common controls and features specific to device PDFWRITE:


This important one presets the "Distiller Parameters", Adobe's documented parameters for controlling the conversion into PDF, to one of four predefined settings (screen, ebook, printer, prepress)


All the ones below are automatically preset according to -dPDFSETTINGS, as per this table. A command suggest by Kurt Pfeifle can be used to check these values. You can fine tune them if you want:


pdfsizeopt full installation instructions

For my other, gs-based answer, see here.

For anyone trying to follow @iNyar's answer to install and try out the pdfsizeopt tool, installing the dependencies is tricky. If you run the tool without installing all dependencies, pdfsizeopt won't run. Here are the errors I got when trying to run it without jbig2, pngout, and sam2p installed:

$ ./pdfsizeopt in.pdf out.pdf
info: This is pdfsizeopt ZIP rUNKNOWN size=69856.
info: prepending to PATH: /home/gabriel/GS/Jobs/Edge Autonomy/Onboarding [29 May 2023 start date!]
error: image optimizer not found on PATH: jbig2
error: image optimizer not found on PATH: pngout
error: image optimizer not found on PATH: sam2p
error: image optimizer not found on PATH: sam2p
fatal: not all image optimizers found (see above), ignore with --do-require-image-optimizers=no

So, the solution is to install the jbig2, pngout, and sam2p dependencies manually. Here are the full installation instructions, therefore, for pdfsizeopt:

Tested in Linux Ubuntu 20.04.

# ================================================
# 1. Install `pdfsizeopt` dependencies
# ================================================

# --------------------
# jbig2:
# - https://github.com/agl/jbig2enc
# --------------------

# install dependencies
sudo apt update 
sudo apt install libleptonica-dev

git clone https://github.com/agl/jbig2enc.git
cd jbig2enc
time make  
sudo make install 
# ensure it is installed
jbig2 --version

# --------------------
# pngout
# - http://advsys.net/ken/utils.htm#pngout
#   - http://www.jonof.id.au/kenutils.html
# --------------------

# download it
wget https://www.jonof.id.au/files/kenutils/pngout-20200115-linux-static.tar.gz
# extract it
tar -xf pngout-20200115-linux-static.tar.gz
cd pngout-20200115-linux-static
# install it
sudo cp -i amd64/pngout-static /usr/local/bin/pngout
# ensure it's installed

# --------------------
# sam2p
# - https://github.com/pts/sam2p
# --------------------

# install dependencies
sudo apt install libgif-dev

# go here and find the latest release:
# https://github.com/pts/sam2p/releases
# Use the correct URL from there in the following commands.

# download it
wget https://github.com/pts/sam2p/releases/download/v0.49.4/sam2p-0.49.4.tar.gz
# extract it
tar -xf sam2p-0.49.4.tar.gz
cd sam2p-0.49.4
time make
sudo make install 
# ensure it's installed by checking its version
sam2p --version

# ================================================
# 2. Install `pdfsizeopt`
# ================================================

curl -L -o pdfsizeopt https://raw.githubusercontent.com/pts/pdfsizeopt/master/pdfsizeopt.single
chmod +x pdfsizeopt
sudo cp -i pdfsizeopt /usr/local/bin/pdfsizeopt

Now use it:

# 1. Check the help menu to ensure it's installed
pdfsizeopt --help 2>&1 | less -RFX

# 2. Use it to optimize in.pdf into out.pdf
pdfsizeopt in.pdf out.pdf

Example run and output:

$ pdfsizeopt in.pdf out.pdf
info: This is pdfsizeopt ZIP rUNKNOWN size=69734.
info: prepending to PATH: /home/gabriel/Downloads/Install_Files/pdfsizeopt/pdfsizeopt/pdfsizeopt_libexec
info: loading PDF from: in.pdf
info: loaded PDF of 1955931 bytes
info: separated to 18 objs + xref + trailer
info: parsed 18 objs
info: found 0 Type1 fonts loaded
info: found 0 Type1C fonts loaded
info: optimized 6 streams, kept 6 zip
info: compressed 0 streams, kept 0 of them uncompressed
info: saving PDF with 18 objs to: out.pdf
info: generated object stream of 523 bytes in 9 objects (21%)
info: generated 1953795 bytes (100%)

Result of running pdfsizeopt above: no change. in.pdf is 2.0 MB, and out.pdf is 2.0 MB. Then again, gs, as described in my other answer, didn't work on this particular PDF either. I don't know why.
Note: for anyone who wants to experiment with this, here is how I created the PDF I'm experimenting on:

  1. Take 3 photos with your phone (Google Pixel 5 in my case). Let Google Photos upload them to the cloud.
  2. Download them into a directory.
  3. Run pdf2searchablepdf -c "path/to/dir" on that dir with the 3 images, to perform OCR on them and combine them into a single PDF. You'll see that
    1. My "compressed" PDF output, using gs under-the-hood, did nothing.
    2. All files are the same size, even though one should be large, medium, small, etc.
  4. Try to compress them with pdfsizeopt and it does nothing for me on these PDFs as well.


  1. @iNyar's answer

  2. ChatGpt helped me a ton to figure out how to install a lot of this mess, in particular calling sudo apt install libgif-dev prior to running time make to build sam2p, else I'd get this error:

    g++ -s -O2 -DHAVE_CONFIG2_H   -fsigned-char -fno-rtti -fno-exceptions -ansi -pedantic -Wall -W -Wextra -c gensi.cpp
    g++ -s   sam2p_main.o appliers.o crc32.o in_ps.o in_tga.o in_pnm.o in_bmp.o in_gif.o in_lbm.o in_xpm.o mapping.o in_pcx.o in_jai.o in_png.o in_jpeg.o in_tiff.o rule.o minips.o encoder.o pts_lzw.o pts_fax.o pts_defl.o error.o image.o gensio.o snprintf.o gensi.o -o sam2p
    /usr/bin/ld: appliers.o: in function `out_gif89a_work(GenBuffer::Writable&, Rule::OutputRule*, Image::SampledInfo*)':
    appliers.cpp:(.text+0x2025): undefined reference to `out_gif_write(GenBuffer::Writable&, Image::Indexed*)'
    collect2: error: ld returned 1 exit status
    make: *** [Makedep:66: sam2p] Error 1

    All words and commands in this answer are my own, however, and I tested everything in this answer personally.


Super simple PDF compress tool: GitHub page.

Installation on Ubuntu:

sudo add-apt-repository ppa:jfswitz/released

sudo apt-get update

sudo apt-get install pdf-compressor

It uses ghostscript.

  • 1
    This is a GUI tool, no?
    – HappyFace
    Commented Sep 22, 2020 at 13:19

I used below commands but it didnt compress my pdf file substantially. Some times some of the portion was blackened after compression.

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

  2. "ps2pdf -dPDFSETTINGS=/ebook %s %s" % (input_file_path, out_file_path)

After too much wandering over the web I just couldn't find the right compression library. I came across pdfcompressor.com. This is just awesome website. It compresses the pdf by 95% ( 15Mb of files). So I used selenium and Tor to automate the compression. Checkout my Github Repository. [GITHUB] (https://github.com/gugli28/PdfCompressor)

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