How To Optimize PDF Files For Smaller Size And Faster Loading


Have you ever found yourself frustrated and swearing at PDF files as you watch the download progress bar move toward the end at a snail’s pace? Surely, there is always a chance the slow download is caused by a poor internet connection, but the truth is that PDF files can be too big even for the fastest internet plans and the most reliable networks.

Luckily, you can take some steps to boost the loading speed of your PDF files without the need to fix network connections.

Understanding PDF and why the size matters

‘Why are my PDFs so large?’ — that’s the question you should start with. While the format allows us to stuff a file with all kinds of content, from simple text to interactive elements, this versatility often makes the document grow in size to tens or even hundreds of megabytes. The result?

Understanding PDF and why the size matters
  • Heavy files equal slow upload and download speeds when sharing PDFs online, which leads to poor user experience, larger bandwidth consumption, and failed downloads. 
  • Since messaging apps, email services, government websites, and many other online platforms limit the maximum size of uploaded files and attachments, you will need to find workarounds instead of simply tapping the Send button.
  • Large documents clutter up storage space on devices, which can affect their performance, and deprive you of free space on cloud storage platforms, making you pay for additional capacities.    

These are enough reasons to start wondering how to reduce the PDF file size, but before jumping into action, we need to figure out what makes it expand and see where the quality may be undermined. Here are some factors to consider:

Number of pages

Each page in a PDF file has its unique structure and content, and a greater number of pages means more information to be stored in the file, resulting in its increased size.

Image quantity and quality

PDF files containing images are generally heavier than those without them. High-resolution images contribute to file size the most, while color imagery takes up more space compared to monochrome or grayscale pictures.


Fonts can be subset and embedded into a PDF. If the document contains non-standard, embedded fonts, it needs to store information about each character of these fonts, making the size skyrocket. 

Additional elements

Bookmarks, links, annotations, tables, charts, meta-data, multimedia, and other elements inserted into the document can inflate its size, although the impact depends on the specific format. 

Method used to create the file

A document scanned to PDF is typically much larger than a file converted via a text processor because of the high standard resolution settings specified in modern scanners. 

Now when we have discovered where our areas for improvement are, we can better understand how to reduce PDF file size without losing quality.

What you can do to make your PDF shrink

Quality is a loose concept, so requirements for PDF file optimization will depend on specific goals. For example, if you're simply looking to save storage space, you don't need to save interactive forms or include color photos in your CV.

What you can do to make your PDF shrink

But if you are a digital artist who uploads a PDF with detailed pictures to impress potential clients, it’s quite a different story. In this case, you would want to optimize PDF files and hit the best balance between retaining the initial quality and cutting the loading speed.

Still, you should be ready to prioritize since a would-be client can lose patience, abort the download, and never see your content if the file is too heavy to open in seconds. 

So, here is a general plan, which can be adapted to your needs:

Start with an audit

There are digital tools with an auditing feature that shows how much space all the images, fonts, structure info, and other elements take within a PDF. They will help spotlight the heaviest parts of initial documents and asses changes after you optimize PDF files to find the most efficient options. 

Get rid of bells and whistles

Some videos, audio files, charts, and pictures serve as eye candy but add little value to a document. With the help of a good PDF editor, you can remove oversized files repeating text content, duplicates, metadata, unnecessary pages, annotations, and everything not required for understanding the document. As an alternative, you can provide links to multimedia files. 

Compress images

When you are through with excess images, you can reduce the size of what is left using an image editor with a built-in compression tool or specialized image compressors and optimizers.

Compress images

Image compression can be used both when creating a PDF and editing it, but for the best result, you will need to get a grasp on some technical details, such as image formats, lossy/lossless methods, niche-specific resolutions, and compression levels.

Revise fonts

Less is more here, so it’s better to avoid using multiple fonts in a PDF or at least replace embedded fonts with some of the standard options like Times New Roman, Courier, or Helvetica. Besides, some PDF editors have the power to remove fonts that are duplicated or not used in a document.

Split or merge files

Both splitting and merging don’t affect the quality of a PDF file since the content remains unchanged, but it leaves you either with several smaller documents or a single file instead of a bunch of documents too bulky to download. With an advanced PDF compressor and merger, you will be able to reorder pages, remove unwanted elements, inspect the target document with a preview tool, and more.   

Compress a PDF

PDF compression doesn’t always boil down to optimizing images within a file. Quite a number of compression algorithms can be used to manipulate different content types, remove hidden data, adjust font settings, flatten layers, and more.

Compress a PDF

Some of them offer completely automated processing, while others provide users with an extensive list of settings to choose from. Apart from online services and downloadable software, there are mobile apps allowing you to compress PDF on iPhone and Android devices.

Bottom line

By going through trial and error, every user can eventually arrive at a perfect way of PDF file optimization and ensure that the size of their documents doesn’t have to work against their workflows and creative processes. With so many helpful digital tools at hand, finding a balance between the quality and loading speed of PDFs is only a matter of willingness.

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