PDFs are firmly established as one of the most common file formats for sharing documents. One of the big reasons why it is such a universally popular option is that it is a smart and convenient way to preserve layout and formatting.
However, there will be occasions when a simple-looking PDF ends up being much larger than expected. This is frustrating as it makes it harder to email, upload, or store.
Why does this happen? There are actually some common reasons why this might happen. Let’s explore some causes and explanations as to why your PDF file is so large, and then provide some helpful tips and guidance on how to reduce PDF document size to where you want it to be.
It is possible that high-resolution images are embedded in the PDF
One of the most frequent culprits behind an unnecessarily bloated PDF file is down to the presence of high-resolution images.
It could be photos, scanned pages, or illustrations. These are all large image files that can very quickly cause your document to become oversized.
The good news is that it is easy to fix this issue without having too much technical know-how. What you need to do is compress the images before adding them to the PDF. You can do this using tools like TinyPNG or Photoshop, who will do all of the technical work for you. These tools reduce image resolution without losing too much quality.
It is also worth noting that using vector graphics where possible, such as SVGs, instead of raster images like JPEG or PNG can also help prevent the problem in the first place..
If the PDF file has already been created, use a PDF editor like Adobe Acrobat or Preview for Mac to compress the entire document.
Unoptimized scans are another common cause
What you can find is that scanned documents often save each page as a high-resolution image rather than actual text and formatting. This results in massive file sizes, especially for multipage documents.
To get around this problem, when scanning, choose a lower DPI (dots per inch). For standard text, 150-200 DPI is usually sufficient. You could also use OCR (Optical Character Recognition) tools during scanning.This is helpful as OCR converts scanned images into searchable and editable text, which significantly reduces the file size.
Bear in mind that many scanner apps and multifunction printers include “small file size” or “compact PDF” settings. Use these tools to avert the issue of a large file size in the first instance.
Custom fonts and embedded content can prove troublesome
Embedding custom fonts and non-standard elements like forms, multimedia, or JavaScript can soon increase a PDF’s size.
While font embedding is a good way to achieve a consistent appearance across devices, it can quickly add hidden bulk. To reduce your file size, you should aim to stick to standard system fonts such as Arial or Times New Roman, which don’t need to be embedded.
If you’re using a PDF creator or editor, look for an option to subset fonts. Using this option means only the characters used will be embedded. Also, avoid embedding unnecessary elements like videos, audio files, or interactive forms unless they are essential to the content.
Redundant metadata and hidden data can soon bloat the file size
PDFs have the ability to accumulate background data like version history, annotations, comments, and metadata. The problem with this is that they aren’t immediately visible but still contribute to the overall file size.
A good way of fixing this particular problem would be to use a PDF cleaner or editor to remove metadata and hidden elements. If you are using Adobe Acrobat, for instance, it has a feature under “Sanitize Document” or “Remove Hidden Information” that helps perform a cleanup of your file and reduce its size.
Another point to note is that flattening annotations and form fields that are no longer needed also reduces size. By saving a copy of the PDF using the “Save As” function, it can rewrite and clean the file. This helps to further minimize space usage.
You may not have applied compression or optimization
Sometimes, it can be the case that the file is overly large simply because no compression or optimization was applied during or after its creation.
Many users don’t realize that exporting to PDF doesn’t automatically optimize the file for sharing. There are several options available to fix this problem. You could use online compression tools like Smallpdf, ILovePDF, or PDFCompressor to shrink your file.
If you’re using Adobe Acrobat, for instance, the way to optimize your file would be to go to File > Save as Other > Reduced Size PDF. You could also use the PDF Optimizer for more control.
If you are using aMac, Preview’s Export option includes a “Reduce File Size” Quartz filter. Alternatively, in Microsoft Word, when saving as a PDF, select the “Minimum size (publishing online)” option to reduce the size.
Some tips to help keep PDF sizes manageable
A good way to prevent any of these issues occuring in the first place would be to remember some useful tips on keeping your PDF file sizes manageable.
A good starting point would be to avoid unnecessary pages or blank spaces, as they add bulk without value. You should also delete any content that doesn’t serve a purpose.
When merging PDFs, use tools that allow you to choose the output quality. If the document is long, consider breaking it into smaller parts. Lastly, instead of attaching large PDFs to emails, you could upload them to a cloud service and share a link.
As these workarounds and fixes demonstrate, a large PDF file doesn’t have to be a headache. By understanding what makes your PDF file so bulky, whether it’s things like massive images, unoptimized scans, or hidden content, you have the ability to take the right steps to slim it down.
Remember, with the right tools and practices, your PDFs will be easier to manage, share, and store, without sacrificing on quality.
