Metric compatible fonts (typically open-source) copy certain metrics from a (typically copyrighted) "source font". "Advance width" at least, and maybe other metrics (I have seen discussions of copying kerning data). Why is this not copyright infringement? Presumably the designer of a metric compatible font is not printing the source font and measuring it. They are using the exact metrics to achieve exactly the same horizontal spacing.

Why does the creation of a metric compatible font not constitute copyright infringement?


1 Answer 1


It is important to distinguish between

  • a typeface, which describes the visual appearance,
  • a font, which may be interpreted as a computer program implementing a typeface, and
  • the name of the font.

These aspects may be subject to different immaterial rights.

  • The name may be subject to trademarks.
  • The font may be copyrighted.
  • The typeface may be protected by copyrights or design patents, highly dependent on the kind of typeface and on the relevant jurisdiction.

A copyright for typefaces is not generally desirable, because this copyright would extend to all documents set in that typeface. Therefore, the U.S. doesn't acknowledge copyright for typefaces. Germany distinguishes between artistic typefaces (eligible for copyright) and utility typefaces (not eligible).

If a typeface is not protected, it is possible to create a new font under a different name that implements the same typeface. This is an extremely common practice. E.g. the popular Helvetica font was cloned multiple times. Arial is heavily based on Helvetica but differs in a few details. Arial was in turn cloned as Liberation Sans. The TeX Gyre Heros font is closely based on Helvetica.

  • Thank you @Amon ... however I am not clear on the distinction between: (A) copying a font's data that represents the shape of the letter "a" (presumably a copyright infringement), and (B) copying the font's data that defines the "advance width" (and maybe side-bearings, and maybe kerning) for "a" (and all the characters) which seems not to be infringement.
    – Clint Goss
    Jan 27, 2018 at 12:04
  • 2
    @ClintGoss I don't really know. But it would seem that while the design of a letter has some creative aspects, the metrics are more technical than creative and therefore don't qualify for copyright. If they are protected by immaterial rights (IP), then by design patterns and not by copyright.
    – amon
    Jan 27, 2018 at 12:27
  • Here is a Moscow Times article that describes a case of metric-compatible font issues involved in USA-Russia relations.
    – Clint Goss
    Feb 2, 2018 at 15:57

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