[Tex/LaTex] Arithmetic in arguments to the geometry package

Question

I'd like to use the geometry package to auto-crop the output of my LaTeX (so that it looks bigger on-screen as I'm editing). I have found a way to remove the margins completely and brutally:

\geometry{paperwidth=\textwidth,  paperheight = \textheight, margin=0cm}

However, I'd like to be somewhat more gentle. I tried the following, but it does not work:

\geometry{paperwidth=\textwidth + 1cm,  paperheight = \textheight+1cm, margin=1cm}

The reason is that arithmetic does not work inside these arguments. (LaTeX doesn't seem smart enough to do the addition).

What is the correct way to achieve this effect?

Answer 1

It works if you load the calc package.

\documentclass{article}

\usepackage{calc}

\usepackage{geometry}

\geometry{paperwidth=\textwidth+1cm,paperheight=\textheight+1cm, margin=1cm}

\usepackage{lipsum}

\begin{document}

\lipsum[1]

\end{document}