\geometry{paperwidth=10mm, paperheight=5mm} % works wrong, and creates multiple pages

[wshppi]

I figured out that small paper height < 6mm cause multiple output pages.

Please try the following example and compare
\geometry{paperwidth=10mm, paperheight=6mm} % works
and
\geometry{paperwidth=10mm, paperheight=5mm} % works wrong, and creates multiple pages

\documentclass[10pt]{article}
\usepackage{geometry}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

\geometry{paperwidth=10mm, paperheight=6mm} % works
% \geometry{paperwidth=10mm, paperheight=5mm} % works wrong, and creates multiple pages

\begin{document}
\noindent\tiny Hello
\end{document}

[davidcarlisle]

This is not really related to the geometry package, you get essentially the same from

\documentclass[10pt]{article}

\setlength\textheight{9.5pt}
\begin{document}
\noindent\tiny Hello
\end{document}

The default value of \topskip (the position of the first line) is 10pt so if you set \textheight to less than that then the page constraints are not achievable and it is impossible to place any text on the page without an overfull box.

[wshppi]

Thank you David, for pointing me to the TeX output log file.
I tried to use very small paper size in the millimeter range for creating very small lables.
Now I will go other ways, e.g. using the textpos package.

Thanks,
Werner Simbuerger

[davidcarlisle]

@wshppi the standalone package may be what you want here it makes the page clipped to the size of the content you provide