Geometry settings for default document layout?

Question

How can I obtain the corresponding settings for the geometry package so that the document looks just like the standard article or report?

Assume that I have a document in the default style, and I would like to modify only some of the layout options; for example, I might want to change the headheight and leave everything else the same.

Try for example the following two option settings for geometry, the first of which shows the default layout, and then how everything changes even if I just wanted to change one of the settings.

\documentclass{article}
\usepackage[showframe,pass]{geometry}
%\usepackage[showframe,headheight=1.5cm]{geometry}
\begin{document}
Hello World
\end{document}

There is a related question (from which I learned about the pass option), but note that the following

\usepackage[showframe,pass,headheight=1.5cm]{geometry}

doesn’t work.

Answer 1

You can compile your document with \usepackage[pass]{geometry}, which will write in the .log file a transcript; here's the result (with A4 paper):

*geometry* driver: auto-detecting
*geometry* detected driver: dvips
*geometry* verbose mode - [ preamble ] result:
* pass: disregarded the geometry package!
* \paperwidth=597.50787pt
* \paperheight=845.04684pt
* \textwidth=345.0pt
* \textheight=598.0pt
* \oddsidemargin=53.0pt
* \evensidemargin=54.0pt
* \topmargin=17.0pt
* \headheight=12.0pt
* \headsep=25.0pt
* \topskip=10.0pt
* \footskip=30.0pt
* \marginparwidth=57.0pt
* \marginparsep=11.0pt
* \columnsep=10.0pt
* \skip\footins=9.0pt plus 4.0pt minus 2.0pt
* \hoffset=0.0pt
* \voffset=0.0pt
* \mag=1000
* \@twocolumnfalse
* \@twosidefalse
* \@mparswitchfalse
* \@reversemarginfalse
* (1in=72.27pt=25.4mm, 1cm=28.453pt)

Since we are in a oneside context, all that should be needed is

\geometry{a4paper,textwidth=345pt,textheight=598pt}

But you can always check against the old transcript.