[Tex/LaTex] How to get a specific font size in baposter

Question

I am trying to create a poster with font size of 12pt. What should be the value of fontscale?

\documentclass[landscape,paperwidth=22in,paperheight=28in,fontscale=?]{baposter}

Answer 1

0.83. I think.

What baposter seems to do is to set the paper width to paperwidth x fontscale, as supplied in the class options, and similar for the height. It then scales the page up again (with help from pgfpages) to the defined paper size. As the base class is article, which uses 10pt as the default, you need 10pt/12pt ≈ 0.83 for fontscale.

\documentclass[paperwidth=22in,paperheight=28in,fontscale=0.833]{baposter}
\begin{document}
Foobar
\end{document}

Here is an attempt at a comparison with article. The different Foobars are from screenshots at the same magnification.