\documentclass[]{article}

\usepackage{gcheck}
\usepackage{calc}
\usepackage{geometry}

% \geometry{compat2,a4paper,mag=1200,truedimen,margin=2cm,
%   twosideshift=10pt,headsep=7pt,headheight=14.5pt}
% The case above can be rewritten without 'compat2' as follows:
 \geometry{a4paper,mag=1200,truedimen,margin=2cm,
   twoside, left=2cm+10pt, right=2cm-10pt,
   includeheadfoot, headsep=7pt,headheight=14.5pt}

\geometry{dvips,showframe}

\begin{document}
\manyfoxes\manyfoxes\manyfoxes\manyfoxes
\manyfoxes\manyfoxes\manyfoxes\manyfoxes

\typeout{}
\dcheck\paperwidth{597.49146pt}
\dcheck\paperheight{845.03174pt}
\dcheck\textwidth{384.11221pt}
\dcheck\textheight{538.8947pt}
\dcheck\oddsidemargin{6.68088pt}
\dcheck\evensidemargin{-13.31912pt}
\dcheck\topmargin{-3.31912pt}
\dcheck\headheight{14.5pt}
\dcheck\headsep{7.0pt}
\dcheck\footskip{30pt}
\dcheck\marginparwidth{65.0pt}
\dcheck\marginparsep{11pt}
\dcheck\columnsep{10pt}
\dcheck\hoffset{0.01344pt}
\dcheck\voffset{0.01344pt}
\ccheck\mag{1200}
\checkresults
\typeout{}

\end{document}
