Originally Posted by JSWolf
72 point on a computer monitor is different then 72 point on an eink screen.
The desk-top publishing point is 1/72 of an inch, and so a 24pt font is therefore 1/3 of an inch high on the grid used to define the font (which is larger than all actual characters). Fonts are always eventually mapped to bitmaps, and then the number of pixels per inch come into play. If there is a mismatch between the actual number of pixels per inch on the screen and the assumed number of pixels per inch in the font bitmap, then the on-screen size will be different than expected.
So far as I can tell, the largest font size on the Cybook is a DTP 24pt (i.e. the same size as 24pt would appear in a printed Word document). I don't know what the Cybook calls this size.