# [EXT] Points, pitch and lines per inch

Philip Taylor P.Taylor at Rhul.Ac.Uk
Sun Feb 9 23:07:38 CET 2020

```Djones9976 via texhax wrote:

> I specified arial 12pt in the preamble of my document.   But how can I
> control the pitch (i.e. characters per inch)

The concept of "pitch" doesn't really exist for proportional fonts (of
which Arial is one instance), as in a proportional font 5 "m"s might
occupy much the same space as 10 "i"s.

> and lines per inch in the document; or how can I tell what the pdf is
> being printed in?

The vertical interline interval (called the "leading" in TeX) is in
normal circumstances controlled by a TeX variable \baselineskip, so you
could add some debugging code to tell you the current value of
\baselineskip — however, if any lines are excessively tall and/or deep,
TeX may ignore \baselineskip and honour some other parameters, into
which I will not go here ...

LaTeX (which is what I assume you are using) does not expect you to
modify \baselineskip directly (it provides, I believe, alternative
control sequences which you /are/ expected to use), but that does not
prevent you from interrogating \baselineskip if you need to know the
intended leading, from which you can then compute the intended lines per
inch.  It will /probably/ be of the order of 14.4pt for a 12pt font
(i.e., roughly five lines per inch) but that statement comes with no
guarantees ...

Philip Taylor
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