I have a couple of bitmapped fonts in the form of *.dfont files. I would like to find out the "native" size(s) for these fonts. By "native" I mean the sizes (in points) of the bitmaps themselves, without any scaling.

I thought that Font Book's ⓘ tab would provide this information, but it doesn't (or it is wrong: the only size information it gives is, invariably, "18pt", which I can see is obviously wrong).

Is there some other way?

  • Technically theres is no native size for a bitmap. But i suppose there was one they designed it for. – joojaa Apr 29 '15 at 11:59
  • I think it might help demonstrate the problem if you screenshot a couple of letters at fairly large scale. – e100 May 1 '15 at 8:01
  • And also specifically why you need the info – e100 May 1 '15 at 8:07
  • We need to know more about the font. Is this a bitmap format or is the font designed to look like a bitmap. – DA01 May 1 '15 at 14:07
  • @DA01: it's definitely a bitmapped font, not a font designed to look like one. – kjo May 1 '15 at 14:36

You could try out Fondu, a command-line tool for converting bitmap .dfont files into the BDF format.

If the conversion is successful, these files can be opened with a text editor and they contain metrics information about each glyph. See the linked Wikipedia page for more details.


I don't have any bitmap fonts to try this but if you open the .dfont file in FontForge (https://fontforge.github.io/en-US/downloads/mac/) it should provide info on the pixel size it is.


I don't think there's really any such thing as a native size in points for a bitmapped font. After all they are comprised of pixels. And even a modern vector font's stated size in points is rather an arbitrary measure.

However, old bitmap Mac system fonts for example assumed 1 point:1 pixel equivalence on screen (72 ppi). So Geneva might have had 9pt, 12pt and 24pt versions. But these are probably better thought of as 9px, 12px and 24px.

Especially as when printing, a higher resolution version could be substituted for the one you specified. So you'd specify 12pt, but the 24pt version would be used to give double the output resolution.

Anyway, going back to the question, you might be able to get a close answer in pixels by counting the number of pixels between ascenders and descenders. Which is not quite the same thing as a font's size. But I think then converting it to points would be an anachronism.

  • I'm fine with counting pixels, but how? There's a Catch-22 for me here, because in order to get a meaningful pixel count, I need to display the font in its "native" size (i.e. without any rescaling). Or else, have some app that will display enlarged versions of the font as it is defined in the dfont file. I'd hoped that FontBook would be such app, but apparently not. My question boils down to what app would show me the font in a way that I can "count pixels" (without any scaling to interfere with getting a true count). – kjo May 1 '15 at 3:10
  • Can't you just set a giant 'A' in Photoshop and count the jaggies on the diagonals? Sure they might get smoothed but if you set it large enough they should still be obvious – e100 May 1 '15 at 7:54
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    The problem with the smoothing is not that it's hard to count the pixel, but rather that, when the letter is smoothed (because it is not in one of the font's native sizes) the number of pixels one counts tells one nothing about what the native sizes are. In other words, in order to use pixel counting as a way to determine a font's native sizes one needs to already know those sizes to begin with, so in the end the pixel-counting method is of no help. – kjo May 1 '15 at 11:17
  • Sorry, don't follow. I think you really need to add a screenshot to your Q – e100 May 1 '15 at 11:23
  • @e100 just like hinting, a bitmap would be designed at a specific size. – DA01 May 1 '15 at 14:09

Modern fonts are usually made up of vector information.More specifically points in space that are connected by lines. They don't have a size. The difference between bitmapped fonts and outline fonts is that the first are composed of several images for each font size. So you have no base font size. A text on a image is not a font, since it cannot be infinitely scaled, and so has a size. My guess is you want to find out the scaling factor with the help of a font editing application. For that you need Fontographer or Glyph or any app with the ability to edit and create fonts. You can read the base size of your outline font from there.

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    No bitmap fonts really do exist. they have no vector. So no not ALL fonts. – joojaa Apr 29 '15 at 11:59
  • Are you sure you're not referring to bitmaps used as fonts ? there is a world of a difference. – lorddarq Apr 29 '15 at 12:06
  • No bitmap font formats do exist, they are a bit before your time. Not common to see them anymore. – joojaa Apr 29 '15 at 12:08
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    True, but I find it hard to believe that he really ment those old types of fonts. That's why I think it was worth clearing up what he understood by "bitmapped font". :) Go through his question again and see why my red flag was raised. – lorddarq Apr 29 '15 at 12:14
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    Also, if he's referring to THOSE old types of bitmapped fonts, then I don't think it's possible, unless he can deflate the dfont file and access all the bundled font sizes. As far as I recall, bitmapped fonts have to have a separate image for each font size. Which also goes to show that there is no "original" or "base" font size. – lorddarq Apr 29 '15 at 12:35

As other's have stated, fonts are bitmaps to begin with. They are vectors. So there is no truly native size.

However, most digital fonts can come with something that is called 'manual hinting'. This means someone went in and made on-screen bitmap copies of each glyph by hand.

So there may be one or more font sizes with this font than will have 'native hinting' for that size.

The catch is that the software has to obey it and there's less of a guarantee today that that will happen. Many operating systems and web browsers can apply their own font smoothing and this is often better (or at least as good) as the old-school hinting files. Some have to apply their own smoothing as they are on high density screens. Of course, as you're probably finding out, a bit-map looking font is something you don't want font smoothing applied to.

If this is a bit-map looking file, then you're probably just best setting it in a few common sizes and see which one looks best. The one that looks best is likely the size(s) that had manual hinting files created. Try 8, 10, 11, 12, 16, 18, 24 pt sizes.

  • The question seems to be about genuinely bitmapped fonts, not hinted vector fonts – e100 May 1 '15 at 7:58
  • @e100 possibly. We'd need the OP to clarify – DA01 May 1 '15 at 14:04

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