Yes. That is, for a given x-height, the width of an 'M' half of what it "should" be for that x-height. According to this:
replyhttps://en.wikipedia.org/wiki/Em_(typography)
it seems the width of an M should be exactly equal to the x-height in points (IIUC).
> However, as a very rough guideline, an "average" font might have [...] an x-height of 48% of the em
replyI guess I somehow skipped that, sorry T_T
replyBut let's look at the font used here on HN. Sure, it's monospace, but it's not particularly thin. Mx ... the x-height is pretty close the em-width. So that quote should probably read "for our idea of typical serif fonts".