Change Page Size in Latex

Goal: The output of the latex on my machine is alway A4, I want to change it to USletter format. There must be more than one way to do this. But I only find one. The solution was found here.

1. install the vmargin package.
2. In pdftex.cfg ($TEXBASE/texmf/pdftex/config/pdftex.cfg) remove or modify the lines:

page_width 210truemm
page_height 297truemm

So that they correspond to your desired default pagesize. An example entry for letter sized paper would read:

page_width 8.5truein
page_height 11.0truein

3. Additionally in the Vmargin style file ($TEXBASE/texmf/tex/latex/misc/Vmargin.sty) at or around line 225 you should change the following default settings so that they reflect the correct default paper size and margins:

\setpapersize{A4}
\setmarginsrb{35mm}{20mm}{25mm}{15mm}{12pt}{11mm}{0pt}{11mm}

Change it to :

\setpapersize{USletter}
\setmarginsrb{1in}{1in}{1in}{1in}{0pt}{0mm}{0pt}{0mm}

Will set up the default page layout to be the standard USLetter (8.5x11.0in) with 1 inch margins and no headers or footers.

It should be noted that for some reason calls to \setpapersize{} that are made within the document seem to be ignored by pdflatex. Even so, it is advised that you include a proper \setpagesize{} and \setmarginsrb{} call so that pagesize can be controlled when building documents with the standard latex package.