I had always known that font size is related to height of the text: What is Font Size?

A font is often measured in pt (points). Points dictate the height of the lettering.

(In my mind, I always it was the height of the letter "M", probably because of "em" size, but it turns out "em" was defined against the width of the letter "M" in the obsolete alternative definition)

Anyways - trying not to make the same mistake as in SVG document units and font size in Inkscape? - I made a document in Inkscape 1.2, changed all units to pt, scale to 1.0; then added text with font size of 12pt, did "Resize to content", and saved:


So, the ultimate size of the document, which is == to the size of the text (the word "Hello"), is 27.3 pt width (makes sense, as this is not a monospaced font, it it to be expected some letters are shorter than "font size" 12 pt, so it is smaller than num_letters*12) ... and 9.24 pt height - which is smaller than font size (12pt), even though I have a capital letter "H" there?

So, what is the actual meaning of font size in Inkscape/SVG? Obviously it is not the height of "M" (nor the width, as it is approximately square). Is there any relation of font size to any visual aspect of any letter? (e.g. "font size specifies 75% of the height of capital letter "A"", or whatever)?

1 Answer 1


OK, I think I got it - "font size" is in fact Body height (typography) - Wikipedia:

Originally, in metal typesetting, the body height or the font (or point) size was defined by the height of the lead cuboid (metal sort) on which the actual font face is moulded.

So, if I type "Heppo" instead of "Hello", I can measure text size height of 11.448 pt in Inkscape - and if I type "Sphinx" (as in the Wikipedia page example), I finally measure text size height of 12.000 pt in Inkscape.

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    Thats what it should mean. But there are all kinds of reasons why it does not actually mean anything useful. Font designer is ultimately able to do whatever they want.
    – joojaa
    Commented Jul 6, 2023 at 15:42
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    Realize that many ascenders, and uppercase curved glyphs (Like S or O), are actually taller than glyphs such as an uppercase H or M. This is done intentionally in order to compensate for optical illusions.
    – Scott
    Commented Jul 6, 2023 at 19:15

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