I started to create a custom theme for beamer slides, and I want to change the default aspect ratio for this theme. Of course I can use \documentclass[aspectratio=169]{beamer} in every document, but I'd like to keep everything in *.sty files. In beamer.cls I found definitions of \beamer@paperwidth and \beamer@paperheight, but setting these lengths in bemerthemeMYTHEME.sty as follows has no effect on the result.


What would be a proper way to change the default aspect ratio in *.sty? Shell I use beamerouterthemeMYTHEME.sty or bemerthemeMYTHEME.sty for this?

  • 1
    Themes really should not be changing the aspect ratio: the two are separate concepts. Can you explain a bit more what you are doing: it sounds like you are making a custom class based on beamer more than a theme.
    – Joseph Wright
    May 3, 2013 at 10:06
  • @Papiro This is not a duplicate, IMO. Based on her/his post, zeliboba already knows how to set the aspect ratio. The question here is how to set the aspect ratio after \documentclass{...}.
    – jub0bs
    May 3, 2013 at 10:10
  • I try to translate corporate PowerPoint style to beamer, they use 16:9 aspect ratio, and I do not want to keep it as an option to \documentclass. Could you please elaborate a bit more on the "concepts"? For me it is just changing the defaults, you can do it with margins, why not with paper size?
    – zeliboba
    May 3, 2013 at 10:15
  • The problem is that a lot of the document settings derive from options passed to the class (such as aspectratio=169). You could probably adjust those settings after \documentclass{...} but you would probably have to rerun a lot of lines from the class file in order to get the desired result. I had a similar problem a while back: I wanted the output to look just as if I had loaded the smaller beamer class option while keeping all my tweaks in my .sty file. It turned out to be unwieldy and I ended up simply passing smaller as an option to the class: \documentclass[smaller]{beamer}.
    – jub0bs
    May 3, 2013 at 10:28
  • So you can do two things: 1) simply pass the class option in the \documentclass{...} command; 2) as Joseph Wright suggested, modify the beamer class file to create your own, which would set the aspect ratio to a different value by default.
    – jub0bs
    May 3, 2013 at 10:38

1 Answer 1


A wrapper class beamer16x9.cls can be easily written:


Then starting a document with


is equivalent to saying


The beamer16x9.cls file should be in one of the canonical places where TeX engines look for input.

  • That's great; much easier than my approach (I'll delete it). However, the difference between typing \documentclass[<options>]{beamer16x9} and typing \documentclass[aspectratio=169,<options>]{beamer} is marginal. I would personally just resign myself to doing the latter.
    – jub0bs
    May 3, 2013 at 11:05
  • @Jubobs With a custom class you might also make other changes, for example the theme-like stuff the OP asked about.
    – Joseph Wright
    May 3, 2013 at 11:15
  • Perfect! I was looking for something like this, thanks.
    – zeliboba
    May 3, 2013 at 12:41
  • Note: this topic may be useful to understand the details of class loading tex.stackexchange.com/questions/9908/…
    – zeliboba
    May 3, 2013 at 14:05

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