How to Reduce the File Size of PDF Documents

How to Reduce the File Size of PDF? Considering PDF documents are well-known for their small file sizes, you may be surprised if your PDF documents turn out quite large. It should be noted that the file size of any given document can vary based on several factors such as its length and the type of content that it contains – but generally there are ways that you can reduce the file size of PDFs.

Compress, Downsample, and Flatten Images

In most PDF files, images are what contributes the most to its file size – so it makes sense that it is a good place to start to optimize your PDF. In particular you will want to compress the images in your PDF and downsample them.

Essentially compression will reduce the file size by getting rid of some of its data and storing the rest more efficiently. The good news is that PDF is a format that supports various options when compressing images and you can choose to use:

  • JPEG 2000 for photos or color images (generally better than JPEG).
  • JBIG2 for monochrome photos and images.
  • ZIP for illustrations, patterns, or any images with areas of solid and flat color.

On top of compressing your images, you can downsample and flatten them as well. Downsampling will reduce the resolution of images, while flattening will merge any transparencies that are on top of images to create a single image instead.

Optimize Embedded Fonts

To ensure that your PDF document looks identical on any device or platform, the fonts that are used are normally embedded as part of the document. Unfortunately that means if you use too many fonts – it could contribute significantly to the file size.

As a rule you should always only embed the specific subset of fonts that you’re using – rather than the entire font itself. On top of that you can opt to not embed certain fonts if you don’t mind an alternative being used in its place when it is viewed.

Discard Unnecessary Elements

While many people avoid it if possible, discarding unnecessary elements is a very effective way to reduce the file size of PDF documents. Forms, JavaScript, embedded page thumbnails, user data, metadata, file attachment, embedded settings, and a wide range of other elements all contribute to the file size.

If you go down this route, you should element which elements are necessary and which ones aren’t needed. In some cases there may be certain elements that are obsolete or unrequired based on how you’re using the document. But in others removing certain elements may affect the document adversely.


Sometimes in addition to compressing and optimizing your PDF documents in this way it may make sense to split them up into smaller documents. Any basic PDF editor can do that, and for example you could try Movavi PDF Editor for Mac (

All said and done however you should now know exactly how you can reduce the file size of any PDF documents. Nowadays there are automated tools that could handle some of the items listed above automatically, which may be worth considering as well.

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