How to Shrink PDF File Size in 6 Methods [Windows & Mac & Mobile]

Esther Joan
Nov 08, 2023

Are you wondering how to shrink PDF file size? To reduce the size of a PDF file, you can use PDF optimization tools or settings in PDF editing software to compress images, subset fonts, remove unnecessary elements, and lower the resolution of images while maintaining acceptable quality. Additionally, you can consider using online PDF compression tools that can automatically reduce the file size without compromising the document's readability. This article introduces several offline & online tools for you to apply.

how to shrink PDF file size


Part 1. What Causes PDF Files to Become Large?

Before searching for how to shrink the file size of a PDF, you should know what causes PDF files to become so large. The size of a PDF file can grow rapidly due to several factors. Here are some common reasons for the increase in PDF file size:

  • Images: Images with a large number of pixels or high-quality settings can make the PDF larger. (Therefore, if you grayscale the images of a PDF file or simply remove these images, you can significantly reduce the size of the PDF.)
  • Fonts: Embedded fonts can also increase the file size, especially if you have many different fonts or include complete font sets. This is often necessary to ensure the correct display of text in the document, but it can increase file size.
  • Multimedia: If your PDF contains embedded multimedia elements like videos or sound, this can significantly increase the file size.
  • Annotations: Adding a large number of annotations, comments, or markups to a PDF can also make it larger.
  • PDF Version: The version of the PDF format you use can affect file size. Newer versions of PDFs may include additional features or metadata that older versions don't have, resulting in larger files.
  • OCR: Running OCR (Optical Character Recognition) on scanned documents can add text data to the file, increasing its size.
  • ...

Extra Tip: How to Determine the Exact Space That Elements Occupy in a PDF?

To achieve that, you'll need to use a specialized tool that provides a detailed analysis of the PDF file. Adobe Acrobat Pro, for example, offers such functionality. Here's how you can do it:

  1. Launch Adobe Acrobat and open the PDF file you want to analyze.
  2. Click on the options "File" > "Save As Other" > "Optimized PDF".
  3. In the dialog box, click the "Audit space usage" button and you'll see a summary of the current file sizes.

click the audit space usage option

Part 2. How to Shrink the Size of a PDF File [Offline]

In this part, you'll learn about how to shrink the size of PDF files on different devices - including Windows, Mac, and even a mobile phone. Read on.

Method 1. How to Shrink a PDF File Size With PDF Compressor [Windows]

PDF Compressor for Windows is a compact and thoughtfully designed PDF compression software that empowers users to control the compression details (such as DPI) for further compression while preserving the quality of your PDFs. It excels at shrinking the size of large PDF files (≥30MB) down to a smaller range (usually between 1~3MB), leading to a compression ratio of 10%.

Key Features

  • A user-friendly slider for compression level adjustment.
  • Rapid compression performance.
  • Compress hundreds of PDF files at the same time.
  • Compression of secured (locked) PDF files.
  • ...

How to Use

01Download, install, and open the PDF Compressor application. Then directly drag & drop your PDFs into the window of the application (or simply hit the "Add"/"Add Folder" option to get your files into the application).

best pdf compressor offline

02Set the compression details and hit the "Start" option to start the compression. When the compression is done, the tool will open the output folder automatically.

choose pdf type

You may also need:

Email Optimization: How to Compress a PDF for Email Effectively

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Method 2. How to Shrink File Size Of PDF With Preview [Mac]

Preview is a built-in application on Mac computers offering a wide range of capabilities beyond basic file viewing, making it a valuable tool for various tasks - including reducing the file size of a PDF.

To shrink the file size of a PDF using Preview on a Mac, follow these steps:

Step 1. Locate the PDF file you want to reduce in size and open it with Preview.

shrink PDF file size with preview

Step 2. Click on "File" in the top menu bar and select "Export" from the drop-down menu.

Step 3. Choose a location to save the compressed PDF. Next to the "Format" drop-down menu, choose "PDF". Below the "Quartz Filter" option, select "Reduce File Size".

reduce file size

Step 4. Click the "Save" button to save the compressed PDF with a smaller file size.

Note: Preview will optimize the PDF file with the "Reduce File Size" filter, which often results in a significant reduction in file size. The quality of the images may be slightly affected, so review the compressed PDF to ensure it meets your quality standards.

Method 3. How to Shrink PDF Files Size with Adobe Acrobat

Shrinking the size of PDF files using Adobe Acrobat is a valuable process for optimizing document storage and sharing. Adobe Acrobat, a widely used PDF management tool, provides a straightforward and effective method to reduce the file size of PDFs.

On Computer

To shrink PDF file size using Adobe Acrobat, follow these steps:

Step 1. Launch Adobe Acrobat Pro and open the PDF file you want to reduce in size.

open pdf with adobe acrobat

Step 2. Click on "File" > "Save As Other" > "Optimized PDF."

click the save as other option

Step 3. In the "Optimize PDF" dialog box, you'll find various options to customize the compression settings. Choose a preset or customize settings manually based on your needs. You can adjust image quality, resolution, and font embedding options.

adobe acrobat pdf optimizer

Step 4. After configuring the settings, click "OK" to initiate the optimization process. Adobe Acrobat will compress the PDF according to your chosen settings.

Step 5. Choose a location to save the optimized PDF and click "Save" to save the compressed PDF file. Then review the compressed PDF to ensure that it meets your quality standards.

save the compressed pdf

On Your Mobile

To shrink PDF file size using Adobe Acrobat on your phone, follow these steps:

Step 1. Download Adobe Acrobat Reader from the Google Play Store on your phone and open the PDF to shrink the file size in the app.

Step 2. Tap the 3-dot icon on the right side of the menu and choose the "Compress PDF" option.

how to shrink a PDF file size on your phone

Step 3. Choose the compression level you prefer and tap the "Compress" button.

compress pdf

Part 3. How to Shrink the File Size of a PDF [Online]

You can also use an online compressor to shrink PDF file size. We're introducing 3 tools in this part. Keep reading.

Tool 1. tools.pdf24.org

The website tools.pdf24.org provides a range of online PDF utilities and has no file size/amount limit. Its user-friendly and intuitive interface allows for effortless reduction of PDF file sizes. Below are the steps to achieve this:

Step 1. Visit tools.pdf24.org and locate the PDF compressor tool. Directly drag & drop your files to the window or click the "Choose files" button to upload your PDFs.

how to shrink file size of PDF online

Step 2. Customize your compression preferences and click the "Compress" button. Afterward, click the "Download" option to download the compressed PDF.

customize your compression preferences

Tool 2. www.ilovepdf.com

www.ilovepdf.com stands as one of the most popular online PDF compressors. This platform serves as a comprehensive hub for various online PDF functions, enabling you to arrange, enhance, and transform your PDF documents. You can compress PDFs in bulk for free on this site.

To shrink the file size of PDFs on www.ilovepdf.com, follow the steps:

Step 1. Visit www.ilovepdf.com and locate the PDF compressor tool. Click the "Select PDF files" button to upload your PDF files.

shrink file size PDF online

Step 2. Choose the compression level and click the "Compress PDF" option.

customize your compression preferences

Step 3. When the files get compressed, the site will automatically start downloading the compressed files to your computer.

Also read:

[Solved] How to Merge PDF Files in Google Drive & Using Alternatives

PDF Size Reducer iLovePDF - Empowering You to Control Your File Sizes

Tool 3. pdfcompressor.com

pdfcompressor.com is a website that allows you to compress PDFs in bulk (≤ 20 files). You can also conveniently use the website to convert or edit your PDF files.

This is how you shrink the file size with this website:

Step 1. Visit pdfcompressor.com and click the "UPLOAD FILES" option to upload your files. The compression will soon start automatically.

how to shrink the size of a PDF file online

Step 2. When the compression is finished, click the "DOWNLOAD ALL" option to start the downloading process.

customize your compression preferences

Ending Part

Shrinking the size of a PDF file is a straightforward process that offers various methods and tools to suit your specific needs. Whether you prefer to work offline using PDF optimization tools or take advantage of online compression services, there are numerous options available to help you reduce your PDF file size while maintaining the document's readability and quality. With the information provided in this article, you now have the knowledge and resources to effectively manage and optimize your PDF files, making them more manageable and easier to share or store.

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