Why are computer users so inefficient

Why are PDFs generated from MS Word so large?

I made a simple MS Word document containing just this sentence:

This is a small document.

Nothing else. Then I saved this document as a DOCX and as a PDF. Here are the file sizes:

DOCX: 12 kB
PDF: 89 kB

That difference is technical huge and bothers me a lot when mainly using text documents Dozens of KB start in DOCX to create PDFs with a Size by hundreds of KB too create. What is so inefficient about PDF format? Or is just Word using a terrible output algorithm?

By the way, the PDF output settings have been set so that the smallest possible file is created:


If you open the PDF in Notepad ++ you will find:

and this object is referenced here at the end of the / FontFile2 instruction:

The fonts used by the Word document are embedded in the PDF file so that the PDF file is self-contained.

I used this slide deck to decipher the PDF instructions.

If you want to prevent the fonts from being embedded in the PDF file, make sure that one of the 14 standard fonts available in PDF viewers is used in your Word document (source Wikipedia).

  • Times New Roman> Times (v3) (regular, italic, bold and bold italic)
  • Courier New> Courier (regular, oblique, bold and bold oblique)
  • Arial> Helvetica (v3) (regular, oblique, bold and bold oblique)
  • Symbol> symbol
  • Wingdings> Zapf Dingbats

This has happened to me many times in Microsoft Word when trying to export a simple manuscript as a PDF. A 5 to 8-page Word document that is approximately 50 KB in size will become a PDF file over 10 MB that is far too large to email anyone.

Rene's answer is on the right track - the problem is fonts are embedded in the document - but using any of the standard fonts won't necessarily solve the problem.

All of my documents were in Times New Roman and were in bold and italics. At least I thought. It turns out that in my default template I use the automatic kerning activated (for obvious reasons). When exporting to PDF, Word actually embed each of these ligatures as a separate font object in the document, making it incredibly bloated.

The update is easy, you just have to remember to do it every time:

  1. Select all of the text in the document.
  2. Format → Font → Advanced
  3. Disable "Kerning for fonts"

Interestingly, you can leave ligatures, contextual alternatives, and other advanced typography features enabled. They have no noticeable impact on the size of the resulting PDF file.

Re-export the document as PDF and it will be approximately 100KB in size. Unfortunately the kerning is below average so I wouldn't recommend printing, but it works fine for emailing a document.

A less technical answer might be for PDF files to use vectors (i.e. math equations) to describe everything you see. All curves and lines are defined by mathematical equations. As a result, there is a lot of information to have on hand, especially if your documents contain images.

This has the advantage that you can theoretically zoom infinitely close without losing resolution or detail, since the lines and curves have no width and can therefore be scaled with your zoom.

Just like the recent change to the Google font reduced the logo size from ~ 14KB to ~ 300KB, simpler fonts are likely to help reduce the file size.

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