6 Ways to Reduce PDF File Size on Mac without Losing Quality

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Megan Charles
February 01, 2024 Preview 226.7K Preview 1
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PDF file usually comes with lots of graphics and images, which may make PDF file size quite large. While, large PDFs often bring troubles when we sending PDFs by email but with a size limit, or the large file eat up too much space on our Mac. In this case, reducing PDF file size on Mac while without losing quality becomes a crucial thing.

To reduce PDF file size on Mac, we can use Preview, free online sites, free PDF Compressor, and paid software. Here in this article we will introduce and compare all the available choice. We know, most of you are worried that reducing the size of the PDF will also reduce the image quality, which makes the PDF unreadable. So we will also introduce specialized software that can compress PDF without reducing the image quality.

 

How we tested the PDF Compressor tools

To help you find which available options works best at reducing PDF file size, we tested 6 PDF compressor tools using three different PDF files each with different size and content. You’ll see how all the tools perform in each scenario — and find out the strengths and weaknesses of each one.

① Number 1 test PDF: A 4.6 MB sized PDF that have 543 pages and are mostly text based, have no images.

② Number 2 test PDF: A 3.6 MB sized PDF that have 60 pages and its content both have images and text.

③ Number 3 test PDF: A 55.1 MB sized PDF that have 23 pages and it's content are mostly images.

 

The Best---Reduce PDF Size on Mac without Losing Quality

If you work with PDF on a regular basis, or your PDF contain personal or company information, and you prefer to choose an specialized software to do the compressing. We recommend you have a try with Cisdem PDF Compressor for Mac.

Cisdem PDF Compressor is a lightweight and easy-to-use PDF compression software. It supports compress multiple PDFs at once on your Mac, with 3 preset PDF compession and 1 custom mode you can reducing the PDF file size by more than half without reducing image quality. 

Also, as it is a offline PDF compressor there is no need to worry about information leakage.

What You Can Expect from Cisdem PDF Compressor?

Tools to compress a PDF file on Mac are plentiful enough, and choosing the best is really not easy. While, the reasons why Cisdem PDF Compressor comes as the best choice is not only due to its high quality compression, but also for a set of benefits it offers to users.

  • Reduce PDF file size without losing quality​---If you have higher requirement on shrinking PDF files on Mac, PDF Compressor Mac allows you to shrink PDF files in 4 modes, Small File Size, Medium File Size and Large File Size, even you can customize the quality by manually inputting the parameters. That's to say, if you choose Small Size Compression, a PDF file in 4.77MB also can be compressed to 45KB in good quality. And no matter how large your PDF is, this Mac program can still offer a way to reduce the PDF file size on Mac below 100kb.
  • Batch compress PDFs---If you need to deal with many PDF files, this program makes it amazingly simple to reduce the size of one or multiple PDF files, which allow Mac users to import up to 50 PDF files at one time. cisdem compressor1
  • Reduce PDF size fast---The compressor processes compression extremely fast, within seconds, you will get files with reduced size. In my test, I compressed a 500-page PDF within 1 minute
  • Compress protected PDF on Mac---Once you have input the correct password within this program, the compressor will continue to reduce your PDF file.cisdem compressor2

Follow the steps to reduce PDF file size on Mac without losing quality

  1. Download Free Trial of Cisdem PDF Compressor.
    Free Download
  2. Drag and drop PDF files into the program or click on the “Add Files” button on the top left corner. You can load batches of PDF files and compress them all at once.batch compress
  3. If you need to reduce the file size of a password protected PDF, you can also use this program. 
    For open password protected PDF the program will recognize and show a lock icon on the PDF and a red lock in the right. Just click on the red lock and enter your password.
    If the PDF has only permission password, the program can reduce the file size without the need to enter a password. 

cisdem compressor2

Click the settings button on the right of the PDF file and choose a compression mode (4 modes available). 

  • See from the screenshot, you know that there are three preset compression modes. The smaller the file size, the lower the image quality will be, so if you want to compress PDF file size without reducing the image quality, select "Large File Size" or "Medium File Size" mode.
  • You can also choose Custom and move the slider to customize the compression level. 
  • If you want to apply the same mode to all added PDFs, check "Apply to all".
  • After completing the settings, click OK. 

    4. Click “Compress” to start shrinking.

Also, you can check the tutorial video of reducing PDF file size on Mac:

Test Result of Reducing PDF Size with Cisdem

Time takes for compression:

① Number 1 test PDF: All the 3 modes take less than 10 seconds.

② Number 2 test PDF: All the 3 modes take less than 10 seconds.

③ Number 3 test PDF: All the 3 modes take less than 20 seconds.

 

②File size after compression:

Number 1 test PDF:

Small File Size Mode: 4.6MB - 3.9MB

Medium File Size Mode: 4.6MB - 3.9MB

Large File Size Mode: 4.6MB - 3.9MB

Number 2 test PDF:

Small File Size Mode: 3.6MB - 962.67KB

Medium File Size Mode: 3.6MB - 1.47MB

Large File Size Mode: 3.6MB - 3.31MB

Number 3 test PDF:

Small File Size Mode: 55.1MB - 6.03MB

Medium File Size Mode: 55.1MB - 15.2MB

Large File Size Mode: 55.1MB - 40.91MB

 

③Quality after compression:

① Number 1 test PDF: All 3 modes gives the same results, nearly no image quality loss.

② Number 2 test PDF: The quality of text stay the same in 3 modes. For images "Large File Size" and "Medium File Size" modes gives almost the same results as the original quality, the picture quality of small size mode is obviously reduced.

③Number 3 test PDF: The "Large File Size" and "Medium File Size" modes gives almost the same results as the original quality, the picture quality of small size mode is obviously reduced.

Picture quality comparison of the 3 modes

See none of them showed any difference in quality from the original quality.

 

Adobe---Use Adobe to Reduce PDF Size on Mac with Good Quality

We all know, Adobe is leading in offering solutions to manage PDFs, its PDF editor, the Adobe Acrobat series is super powerful to handle all kinds of PDF files, including reducing PDF on mac with good quality.

First, Can Adobe Reader Reduce PDF File Size on Mac?

One of my friends once asked me if Adobe Reader can reduce pdf file size on Mac, the answer is NO.

Adobe Reader is a free PDF viewer open to everyone from Adobe, it allows users to view, highlight, add notes, print, fill and sign PDF. But if you need advanced features, such as editing, creating, exporting, compressing, etc., you will have to subscribe its Acrobat version.

Now, Use Adobe Acrobat Pro to Reduce PDF File Size on Mac with Good Quality

  1. Open the PDF you want to reduce with Adobe Acrobat DC.
  2. Go to Tools > Optimize PDF, choose Reduce File Size to shrink PDF on Mac.adobe acrobat dc reduce pdf
  3. Choose “Reduce File Size” in the toolbar (you can also start advanced optimization or optimizing scanned pages according to your needs.)reduce file size mac adobe1

  4. Then set the Acrobat version compatibility, you can apply it to multiple files.reduce file size mac adobe2

  5. Press OK to save the smaller PDF file.

Test Result of Reducing PDF Size with Adobe Acrobat

①Time takes for compression:

Number 1 test PDF: All the 3 modes take less than 30 seconds.

Number 2 test PDF: According to the modes you choose it takes between 20 seconds to 1 minutes.

Number 3 test PDF: All the 3 modes take less than 30 seconds.

 

②File size after compression:

Number 1 test PDF:

Adobe High Compression Mode: 4.6MB - 3.9MB

Adobe Medium Compression Mode: 4.6MB - 3.9MB

Adobe Low Compression Mode: 4.6MB - 3.9MB

Number 2 test PDF:

Adobe High Compression Mode: 3.6MB - 1.1MB

Adobe Medium Compression Mode: 3.6MB - 2.46MB

Adobe Low Compression Mode: 3.6MB - 3.38MB

Number 3 test PDF:

Adobe High Compression Mode: 55.1MB - 11.9MB

Adobe Medium Compression Mode: 55.1MB - 16.38MB

Adobe Low Compression Mode: 55.1MB - 17.9MB

 

③Quality after compression

Number 1 test PDF: All 3 modes gives the same results, nearly no quality loss.

Number 2 test PDF: The quality of text stay the same in 3 modes. For images you'll see image quality degree in "High Compression" and "Medium Compression" modes. While for the Low Compression mode it gives the same quality of the original PDF.

Number 3 test PDF: You'll see image quality degree greatly in High Compression mode, the Medium Compression mode gives almost the same quality as Low Compression.

 

Free---Reduce PDF File Size on Mac Free

A Mac is designed to boost productivity both in life and work, so it is quite reasonable that some powerful applications comes with MacOS for totally free. Among these apps, there are 2 Mac tools can reduce PDF file size on Mac for free. One is Preview, while the other one is Colorsync.

#1 Reduce PDF File Size on Mac Free with Preview

Preview is the free Mac program developed to view and manage PDFs or images. With 3 steps, Preview can get your PDF file size reduced.

  • Step 1. Open PDF with Preview
  • Step 2. Go to File > Export > Quartz, choose “Reduce File Size”
  • Step 3. Click “Save”.compress pdf mac preview

Test Result of Reducing PDF Size with Preview

①Time takes for compression:

Number 1 test PDF: 25 seconds.

Number 2 test PDF: 13 seconds.

Number 3 test PDF: 37 seconds.

 

②File size after compression:

Number 1 test PDF: 4.6MB - 10.3MB

Number 2 test PDF: 3.6MB - 3.2MB

Number 3 test PDF: 55.1MB - 63.6MB

You see, In our test, the largest downside of using preview to compress PDF on Mac is, it will always increase the size of PDF file, instead of compress it.

 

③Quality after compression:

What surprise us is that although it increased the size of the PDF file, but it also lowered the quality of the output PDF file.

Disadvantages:

  • File quality is lost to some extent
  • Doesn't work on PDFs with complicate elements (images, texts, tables, etc.)
  • Cannot batch reduce pdf file size on Mac 
     

#2 Compress PDF on Mac Free with ColorSync

Another Mac tool to compress PDF is ColorSync, it is a color management system, helping users to modify an image by adding effect, tweaking color space, adjusting colors or brightness, etc.

  • Step 1. Go to Finder > Application folder, and open ColorSync Utility
  • Step 2. Go to File > Open, you will navigated top open PDF with ColorSync.
  • Step 3. In the Filter menu, choose “Reduce File Size”, then click “Apply”.colorsync-open
  • Step 4. Go to File > Save as > Save.colorsync reduce

Test Result of Reducing PDF Size with ColorSync

In our test, it gives almost the same result as preview.

Disadvantages:

  • File quality can be easily sacrificed
  • Doesn't work on PDFs with complicate elements(images, texts, tables, etc.)
  • Doesn't support batch compressing

If these 2 solutions don't help, have a try on the best PDF Compressor for Mac.

 

Online---Compress PDF on Mac Online without Losing Quality

Most online PDF compressors are free, which makes them the most affordable way to compress PDF on Mac. However, in the case of large PDF files, you need to upload and download them, so it may take a long time to process. Also, there are many sites online that claim to be able to compress PDFs, but you should be careful as some sites have a lot of advertisements but are not very effective. If the site is suspicious, you may be worried about information being leaked.

If you want to reduce PDF file size on Mac without losing quality online, you’d better use following 2 online tools.

#1 PDFCompressor

After testing all the online PDF compressors ranked in the top 2 pages of Google results, PDFCompressor finally comes as my favorite online choice. It can compress a PDF file as small as possible, also reduce the file size without losing original quality. Even, it supports to reduce a single or multiple PDFs in batch.

In my test of compressing a 4.4MB-PDF file, PDFCompressor helps to reduce the file size to 635kb, while the quality is not lost, such as its layout, image resolution are not sacrificed.

Follow the steps to reduce PDF file size on mac online

  • Step 1. Go to PDFCompressor.
  • Step 2. Drag and drop single or multiple PDF files into the working area. Once the files are uploaded, the compression starts.pdfcompressor
  • Step 3. Click “Download” or “Download All” to get the reduced PDF file online.

Cons:

  • Potential risk of information leakage
  • Internet connection and file size will greatly impact the compressing
  • The conversion quality will greatly depend on the file itself, it maybe unstable

Test Result of Reducing PDF Size with PDFCompressor

①Time takes for compression:

Number 1 test PDF: 25 seconds.

Number 2 test PDF: 13 seconds.

Number 3 test PDF: 37 seconds.

 

②File size after compression:

Number 1 test PDF: 4.6MB - 3.9MB

Number 2 test PDF: 3.6MB - 1.8MB

Number 3 test PDF: 55.1MB - 28.7MB

 

③Quality after compression:

Reducing the file size also reduces the image quality. This is what this online site will show you, you will see files which are largely text will keep the quality but for files with a lot of images the quality will also reduced, and some even unusable.

#2 Smallpdf

When it comes to online PDF compressor, the most popular is Smallpdf.com. It is the platform enjoys large popularity to provide various online PDF services. You can upload single PDF for compression from local, GoogleDrive or Dropbox. 

However, Smallpdf also has some shortcomings. For example, you need to bear the advertisements on the screen, and you cannot compress PDF files in batch. Also, a defaulted mode is set for users. For instance, a PDF file in 1.77MB will be compressed to 716.27KB.

Follow the steps to compress PDF on Mac Online

  • Step 1. Go to Smallpdf.com to visit this site and choose Compress PDF tool.reduce file size mac online1
  • Step 2. Drag and drop your PDF file to Smallpdf. 
    There are 3 ways for you to add PDF file, you can click “Choose File” to add, or just add by drag-n-drop, or you can add from Google Drive, Dropbox. 
  • Step 3. Then click “Download File Now” to download your compressed PDF file, or you can choose to save in your Google Drive or Dropbox.reduce file size mac online2

Cons:

  • Batch compressing is not free
  • Potential risk of information leakage since your file is uploaded to the server for processing
  • Internet connection and file size will greatly impact the compressing 

 

Test Result of Reducing PDF Size with Smallpdf Online

①Time takes for compression:

Number 1 test PDF: In our test this online sites shows that the first PDF is already pretty compressed. 

Number 2 test PDF: 19 seconds.

Number 3 test PDF: 59 seconds.

 

②File size after compression:

Number 1 test PDF: Failed

Number 2 test PDF: 3.6MB - 1.5MB

Number 3 test PDF: 55.1MB - 14.9MB

 

③Quality after compression:

The online site don't support compressing PDF files that are mainly text and the output quality is merely satisfactory, with some images turn out blurred. 

As there are lots of online free PDF compressors available, you may want to try others for a wiser decision. No need to do this yourself, we have done a review of several top online pdf compressor for your consideration.

 

Extended: How to Reduce PDF Size on Mac Using Command Line

An extended way to reduce PDF file size on Mac is using command line. Here we need to use Ghostscript, a standalone command line application and interpreter for the PostScript language and PDF documents. Ghostscript’s standpoints include file compression, file conversion with OCR technology, color management, printing, etc. Now, follow our steps and try this way if you are not new to the command line.

  1. First, use brew to install Ghostscript program on your Mac:
    brew install ghostscript
  2. Now, you can compress the PDF file using the following command line:
    ghostscript -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile="output.pdf" input.pdfreduce file size mac command1
  3. Pay attention that you need to replace “input.pdf” with the PDF file that you need to reduce size, and replace “output.pdf” with the path to the output folder on your computer.reduce file size mac command2
  4. Then you can find the compressed PDF file in the output folder you set up. (We tested a 60MB PDF file with both text and images and input it to the program. As the output file shows, it reduced to 3.28MB)

 

Small Tips to Compress PDF on Mac

If you are not intended to reduce pdf file size with a software or online service, here are some small tips to compress pdf for you.

  1. Keep the image smaller: Very often, it is the images taking too much space. So, when you are working on PDFs, try to include an image in JPG format, which is in relatively smaller size.
  2. Delete unnecessary pages or images: Directly remove some pages or images (even multimedia objects) that are not necessary in your file. 
  3. Convert PDF to other formats: This really works when you are working on PDF image files or scanned PDF. I did this for several times, when I exported PDF in editable Word, or other formats, I did get a smaller PDF file.

 

Final Words

If you only need to compress 1 or 2 PDFs, I recommend using the standard Mac app or a free online site, especially if your file is small. If you often need to work with PDFs, or if you want to compress PDF company documents or PDFs with personal information, we recommend using specialized software. 

If you don't mind the high cost, the best option is to use Adobe Acrobat, but if you want a more efficient way to reduce PDF files on your Mac and want a convenient and affordable option, Cisdem PDF Compressor is recommended.

Free Download macOS 10.11 or later Free Download Windows 11/10/8/7

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Megan Charles
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Megan has an impressive deal of experience with Mac software and has the ability to explain tech stuff in a simplified, straightforward and easy to understand way.

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  • Henry B

    I also got huge frustration from large size PDFs, I tried to compress in Adobe, but still too large to be viewed by our office software. Until I tried your method 2 and 3, and I personally recommend method 2, though you have to pay for it, it saves work.

    7 years ago commonReply

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