List of average page number per journal There are lists of journals in various fields of science by impact factor, cites per document, total cites, etc. 

Does there exist something comparable if I want to know the average number of pages per article?
There is no certain rule of thumb for determining the number of pages in a journal article. If you are asking for a sheet with all the information about it, then I think nobody here is going to be able to help you out. If you need information on a specific journal, however, then you may look into the journal's "Author Information/Instruction" page or "Paper Submission Page".

However, you should also note that there are often three different types of paper welcomed by many journals:


Short paper (least number of pages) E.g. 8 pages for IEEE
Regular paper (more pages) e.g. typically 12 double column pages
Review papers (most pages). e.g. I don't know.


However, everything depends again on publishers, including whether it is a double column or a single column format. Typically single column formats have higher page numbers than the examples given above.