PDF Compression: The Complete Guide

Learn How to and Why You Should Compress PDF Files


When Adobe developed Portable Document Format (PDF) in the early 90s, a lot of document sharing issues that drove organizations crazy virtually disappeared. Since files saved as “.pdf” maintain their formatting regardless of the operating system or computer type, sending and receiving documents became exponentially easier.

If transferring and storing PDFs is something you do often, you’re probably familiar with file compression. It’s a great way to speed up the transfer process and when dealing with large amounts of data, compressed PDFs take up a lot less space.

While the mechanics behind it can seem complicated, it’s actually quite simple to understand when broken down. Lucky for you, this post is going to help give you a more solid understanding of what happens when you compress PDF files and why it’s so beneficial.

What is a PDF?

Portable Document Format files, or PDFs, are a type of file format that looks and functions the same way across all operating systems, regardless of how many times they’re transferred or what hardware is being used. With the ability to contain images, text, links, videos, and a wide assortment of other data types, PDF files are great for sharing and storing documents on servers accessible by many people.

PDF files are great for businesses because they can easily be password protected to ensure that only authorized users have access to view or make edits. This creates another layer of security without having to implement additional software.

Another highly advantageous feature of PDF files is the ability to digitally sign documents. Instead of printing, signing, and scanning to capture a signature, it’s possible to electronically sign documents while simultaneously preventing users from changing the content.

What is PDF Compression?

While PDF files are relatively small, they’re still able to be compressed to take up even less space; this is great when dealing with large quantities of files that need to be stored or shared.

PDF Compression Image

In order to maintain the file’s quality and structure, the preferred method of compression is something called “lossless compression”. This ensures the PDF doesn’t lose any information when it’s reduced in size.

So how does a document shrink without suffering from a loss of data?

It all has to do with managing redundancy. Most files contain several duplicates of the same information that can be eliminated without harming the original content.

Here’s an example: Say you have a PDF with an image that contains only 3 colors. These colors are made up of thousands of pixels, side by side, to show a solid, colored surface area. In its original format, the PDF counts each of these pixels individually - red pixel 1, red pixel 2, red pixel 3 – until it accounts for every single one. When compressed, the PDF looks at all of these red pixels as a single element instead of separating them. So say there are 360 red pixels; it would code this as “360 red” to make it a single block of data. It does this using something called run-length encoding (RLE), which is a type of compression algorithm that takes a string of repeating data and reduces the number of bytes it takes up.

Why Bother Compressing PDFs?

Reducing the size of a PDF without damaging the content sounds nice and all, but why bother doing it if these files are usually small to begin with? Wouldn’t it be faster to just keep the files as they are?

Believe it or not, there are some huge benefits to compressing PDFs. If you or your company value organization and efficient methods of handling large quantities of data, compression is a must.


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The main benefits can be broken down into three categories – speed, storage, and security:

  • Transfer speed – If you send and receive a lot of PDFs as email attachments, you know that it can slow down your servers. A great way to cut down on this heavy traffic is by sending smaller files, and compression is a simple way to handle this.

    Not only will it take less time to share files, but it allows you to create a zipped folder containing multiple PDFs that can be sent at the same time. All the recipient has to do is extract the folder, and they’re left with all of the files in their original format.

  • Storage efficiency – Say you have hundreds, maybe even thousands, of PDFs you need to archive. Sure a single document doesn’t take up much space, but they definitely add up when in bulk. With compression, you can drastically cut down the amount of server space you need to house all of your files.

    If you place all of your PDFs in a single zipped folder and store it on your server, it will take up exponentially less space than if they were kept in their original, uncompressed format.

  • Security – Compressing a PDF file allows you to add password-protection to sensitive documents. WinZip features AES encryption, which makes it easy to not only set passwords for files but control what gets encrypted and who has access to view and edit.

How to Compress/Decompress PDF Files

You should have a pretty good understanding of what PDF compression is and why it’s beneficial, but how is it done?

Using WinZip, the process couldn’t be easier. Here’s the fastest way to compress a file:

  1. Locate the file(s) you want to Zip

  2. Right-click to open the WinZip submenu where you are given 2 options

    • Add to Zip file: This allows you to create your own Zip file name, compression type, method of encryption, etc.
    • Add to [filename].zip(x): This option creates the Zip file using the default compression method.
  3. That’s it; your Zip file is now created

Compressing a file is no good if you can’t decompress it, so let’s look at how that’s done:

  1. Locate and open the zipped folder that contains your PDF(s)

  2. If it’s a single file, simply drag it from the zipped folder to a new location

  3. If you’re dealing with multiple PDFs, right-click the folder and select “Extract All”

That’s really all there is to it. Simple, right?

Watermarking PDF

PDF Compression Image

Sometimes you want to add a bit more protection to your documents to keep others from taking credit for your work. What better way to do this than with a watermark?

WinZip makes the process of adding watermarks to your PDF files quick and easy; let’s go over how it’s done:

  1. Open your PDF document in WinZip and select the “Watermark” option on the Action pane

  2. Click “Options”

  3. Choose “Watermark settings”. You’re given the ability to customize how your watermark should appear – everything from font, to opacity, to placement

  4. Set your settings the way you like, then click “Save”

It only takes 4 steps to add another level of security to your PDF files.

A Simple Tool with Incredible Value

PDF compression isn’t as complex as it seems. It’s simply taking existing data, cutting out unnecessary information, and reformatting it to a more manageable size. The content remains the same, but transferring and storing is much more efficient.

If you’re someone who enjoys the many features and benefits of PDF files, utilizing compression only makes it that much better. If you want to learn more about compression and how it functions with PDF files, check out WinZip for more information.


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