I use beamerposter with pdfLateX. I normally make the poster for A0 page size but need to reduce the size of (scale) the poster to a specific width to fit a smaller size frame used for showing posters in our department. I realize I could design the poster for a smaller size but still I need to switch between size. So, is there a simple way to scale the entire poster with its content already when compiling it?
As posters are typically printed only once or twice, I would not bother too much about configuring the final page format in the LaTeX source. Instead just post-process the resulting PDF to fit the required paper format.
Many printing systems provide a "scale" or "auto-scale" option to fit some given content to the selected page size. If you have to to specify it manually, you give a scale factor of 1/√2 (0.707) to go down one A paper format.
If you actually do need a pdf of the requested size (because somebody else is going to print it), either "print to PDF" or employ the