% Graph paper A4 21 x 29.7 cm
\documentclass{article}
\usepackage[a4paper, portrait, hmargin=2cm, vmargin=2cm]{geometry}
\usepackage{tikz}
\def\width{16cm}
\def\height{25cm}
\thispagestyle{empty}

\begin{document}
\begin{center}
\begin{tikzpicture}
  \draw[step=2mm, line width=0.1mm, black!30!white] (0,0) grid (\width,\height);
  \draw[step=1cm, line width=0.2mm, black] (0,0) grid (\width,\height);
  \draw[step=5cm, line width=0.35mm, black] (0,0) grid (\width,\height);
\end{tikzpicture}
\end{center}
\end{document}