Reducing PDF File Sizes

On a client’s site, we recently found a link to a PDF. The PDF was 40 MB, which is huge.

Using common software, WebSanity was able to reduce it to 385 KB. Yes, KB. That’s .09625% of the original size!

Most of the time, if you have PDFs over a few MBs, something is probably wrong, so you should try to reduce them.


Here are some recommendations, both free:

Mac OS X

On a Mac you just use Preview, which comes with your computer1.

  1. Open the PDF in Preview.
  2. Go to File > Duplicate.
  3. Once the duplicate is created, go to File > Save.
  4. For Quartz Filter, select Reduce File Size (if you don’t see Quartz Filter, press the little triangle to the right of the file name).
  5. Figure out where to save the PDF. If you’re uploading it to your website, just save it on your Desktop & then delete it when it’s uploaded.
  6. Press Save.


There are lots of websites out there that will let you upload a PDF & get back one that is smaller. The problem is that most of these sites limit how big your PDF can be. With that caveat in mind, you might find one of these sites useful:

  1. If you use a Mac, you really don’t need Adobe Reader, unless you need to fill out forms. Preview, which is free & comes with every Mac, is powerful and works great for reading PDFs (& a whole lot more, actually!).