# How do you effectively debug overfull \hbox warnings?

I still haven't found out how to effectively solve Overfull \hbox (0.80913pt too wide) has occurred while \output is active warnings.

For instance, this piece of latex generates such a warning and I am stumped why:

\newcommand\Header{%
\noindent\makebox[\textwidth][l]{
\parbox{0.5\textwidth}{\contactinfo}
\parbox{0.5\textwidth}{%
\hfill\includegraphics[height=25pt]{logo}}}\par\vskip1ex%
\par\ColTopRule\par}


\contactinfo is defined as follows:

\newcommand\contactinfo{\fontsize{8pt}{8}\selectfont\headerfnt Streetname 12324 \\ PostalCode City \\ +31655555555555}


Error:

*geometry detected driver: pdftex*
<logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]
[1] <logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]
[2] <logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]
[3] <logo.eps>
Overfull \hbox (0.80913pt too wide) has occurred while \output is active
[]


Expected output is:

Streetname 12324                                       here comes
PostalCode City                                          the logo
+31655555555555                                     right aligned
-----------------------------------------------------------------


I mean, both boxes have a length of 0.5\textwidth, the text is obviously smaller than this, as is the logo. How come it still generates such a warning? And how can I found out why?

-
You need to escape spaces with %. E.g. \noindent\makebox[\textwidth][l]{% – Marco Daniel Apr 13 '12 at 11:50
did that: \newcommand\Header{% \noindent\makebox[\textwidth][l]{ \parbox{0.5\textwidth}{\contactinfo} \parbox{0.5\textwidth}{% \hfill\includegraphics[height=25pt]{logo}}}\par\vskip1ex% \par\ColTopRule\par} error remains – grrrbytes Apr 13 '12 at 11:54
hard to see in the comment formatting but you still have a space before each of the \parbox commands in that comment – David Carlisle Apr 13 '12 at 11:58
weird, I removed all spaces. To no avail – grrrbytes Apr 13 '12 at 12:01
\makebox[\textwidth]{...} doesn't care if you put something larger than \textwidth in it. So I doubt that the problem is from the content. I guess that you either have a additional space at the place where you use your \Header command or a non-zero \parfillskip value. Make a complete example. – Ulrike Fischer Apr 13 '12 at 12:37

## 1 Answer

To answer the general question about how to debug the box warnings add

\showboxdepth=\maxdimen
\showboxbreadth=\maxdimen


or if that is too much information

\showboxdepth=5
\showboxbreadth=5


and then whenever TeX is showing box information in the log it will show you a representation of the contents of the box.

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Could you please tell where should I add the above commands? – Shray Sharan Aug 19 '15 at 14:39
@ShraySharan anywhere before the offending code, the preamble of the document for example. – David Carlisle Aug 19 '15 at 20:40
Overfull \hbox (4.0pt too wide) has occurred while \output is active [] \hbox(0.0+0.0)x430.0074, glue set - 1.0 .\glue 3.0 plus 1.5 minus 1.0 .\glue 3.0 plus 1.5 minus 1.0 .\vbox(0.0+0.0)x430.0074 ..\hbox(0.0+0.0)x430.0074 ...\hbox(0.0+0.0)x0.0, glue set - 430.00739fil ....\vbox(0.0+0.0)x430.0074 .....\hbox(0.0+0.0)x430.0074, glue set 215.0037fil [] ....\glue 0.0 plus 1.0fil minus 1.0fil – Shray Sharan Aug 20 '15 at 14:28
I have messages as in the above comment in the log file. I dont understand their meaning. Also when I click on the warning, it doesn't redirect me the line of code that has the warning.. Could you please help me out on this? – Shray Sharan Aug 20 '15 at 14:29
@ShraySharan you have something (most likely in the page head) that is 4pt wider than the page. – David Carlisle Aug 20 '15 at 15:55