Type 1, TrueType and the other PDF font types carry a font program, with an outline for each character. A Type 3 font has none. In the standard’s words, “In Type 3 fonts, glyphs shall be defined by streams of PDF graphics operators.” Each character is a little drawing, which may be outlines, filled shapes or a bitmap. That freedom has costs: “However, Type 3 fonts have no hinting mechanism for improving output at small sizes or low resolutions.”

Who makes Type 3 fonts?

Two sources are well documented:

  • Matplotlib. Its default settings include pdf.fonttype: 3 (“Output Type 3 (Type3) or Type 42 (TrueType)”), so a chart saved as PDF with the defaults carries Type 3 text.
  • TeX with bitmap fonts. The TeX FAQ explains that most TeX systems configure dvips to use pk bitmap files, and that pdfTeX falls back to them when it has no alternative. On screen, in the FAQ’s words, such “characters show up in Readers display as blurred blobs which are often not even recognisable as the original letter”. The PDF standard ties such bitmap characters to Type 3 fonts: its section on image masks says that “an image mask, rather than an image, should almost always be used to paint glyph bitmaps”, for reasons it gives in the section on Type 3 fonts.

Where do you see a Type 3 font?

  • pdffonts lists it with Type 3 in the type column, possibly with no name. A minimal test file we wrote by hand on October 12, 2026, with one Type 3 font that draws two characters:
name                                 type              encoding         emb sub uni object ID
------------------------------------ ----------------- ---------------- --- --- --- ---------
[none]                               Type 3            Custom           yes no  no       5  0
  • Document Properties > Fonts in Acrobat and Reader lists each font of the file with its type.
  • Paper checkers. Some conferences reject them: the camera-ready instructions for ACM SIGOPS ATC 2026 say “papers should have Type 1 fonts (scalable), not Type 3 (bit-mapped)”.
  • PDF Textfix locks every line drawn in a Type 3 font. The lock gives the reason: “This text is drawn with a font made of pictures, so PDF Textfix cannot write new text in it.” The Issues pane lists those lines, and the manual’s list of locked lines explains each reason.

Why can’t you type new letters in a Type 3 font?

A Type 3 font holds only the drawings its producer put in it, and there is no font program to draw a letter it lacks. A letter it already holds could in principle be drawn again, but the names attached to the drawings need not say which character each shows, so even copying the text can fail. PDF Textfix does not edit Type 3 text; it leaves those lines unchanged when it saves your other edits. Text you cannot select or copy is covered in Can’t select or copy text in a PDF.

How do you get rid of Type 3 fonts?

At the source, by making the PDF again with outline fonts:

  • Matplotlib: set the font type to TrueType before saving the figure.
import matplotlib
matplotlib.rcParams["pdf.fonttype"] = 42
  • TeX: use the Type 1 versions of the fonts; the TeX FAQ gives dvips -Ppdf for the dvips route.
  • Other tools: look for an export option that embeds TrueType or Type 1 fonts, or that keeps text as text.

Regenerating the PDF is the dependable fix. Converting the drawings back into a real font after the fact is guesswork.

Questions about Type 3 fonts

How do I check a PDF for Type 3 fonts?

Run pdffonts file.pdf and read the type column, or open Document Properties > Fonts in Acrobat or Reader.

Are Type 3 fonts embedded?

Always, in the sense that their drawings live in the file; there is nothing outside the file to load. That is why pdffonts says yes under emb.

Can I download a Type 3 font?

No. A Type 3 font exists only inside its PDF. The fix is to export the document again with an outline font.