%% xdpyinfo|grep dots
resolution: 129x129 dots per inch

However, I don't like it. A DPI of 96 looks natural to me and a DPI of 129 makes the "standard" font sizes too large. *shrugs*

Thanks for the comment.

echo "sqrt(WidthInPixels^2+heightInPixels^2)/DiagonalViewingArea" | bc

which results in 86 DPI for my 19" lcd with a resolution of 1280x1024

just wanted to point this out because many people simply use 96 DPI because it's so common.

have a look at http://www.raydreams.com/docs/dpi.html for more infos

I couldn't find it in the menu, so thanks for letting me know! I will add an update to my post.

@dav_it: Glad I could help!

It's Xfce. It's easy to use. Users shouldn't have to touch text config files to get good fonts.

In fact, there's a handy graphical control for DPI built right into Xfce; it was added to the UI-settings-manager one or two versions ago.

Menu --> Settings --> User Interface Preferences
Click the Font DPI dropdown, and select your desired DPI (96 is common; it's what I use on my systems).

Make sure to Save session for future logins when you logout, and your DPI is preserved. Never do it the Xubuntu way, I'd say.

Presto. No muss, no fuss. No editing nasty text files; it's much easier to make the changes where you should -- with the provided graphical tool.