screen physical size, DPI, font size - how does it work?

Alexej Davidov alexej.davidov at
Sun Oct 7 12:18:31 PDT 2007

On Sun, 07 Oct 2007 16:15:02 +0100
Ross Burton <ross at> wrote:

> On Sun, 2007-10-07 at 14:37 +0200, Alexej Davidov wrote:
> > The other thing is: if I set the resolution to the theoretically
> > correct value, which is 125x125 dpi in my case (1400x1025 at
> > 285x215mm), all the fonts are far to big. 
> The fonts are not too big, they are the correct size.  You are
> specifying sizes in points, so by changing the relation between pixels
> and inches, the size of the fonts obviously changes.
You're right. Guess I was just so used of setting font sizes in the
range 12-14, that I couldn't believe they were so big.

> You can verify this by setting the screen font size to something like
> 18pt, printing out some text at 18pt, and then compare them.  For
> typical setups like a monitor on a desk, set the correct DPI and then
> set the font size to the right size.
Printing and comparing doesn't really work. But I guess that's a
problem of font substitution for the printer. Not only are the heights
slightly different, also kerning, etc. But I don't believe in WYSIWYG

> My laptop's screen is 246x185mm at 1024x786 which works out to 105dpi,
> and my preferred widget font size is 7.5pt.
The default settings for GTK, QT, TK, IceWM, xterm, etc. are all much
bigger. More like 12-14pt. Is this, because everybody has set a too low
dpi value anyway and thus the default font setting are so big to
compensate for this?

> Ross

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