The size most stock templates assume
Eleven by seventeen inches is the familiar American tabloid, the same footprint as two letter sheets side by side. That matters practically: it is the size the majority of newspaper templates in Canva, Adobe Express and stock template libraries are built to, so if you are starting from a downloaded layout it is more likely to fit here than anywhere else.
It is also the size most people picture when they think of a smaller newspaper, so it carries the visual cue you probably want without the handling difficulties of a full broadsheet. The printable area comes to 10 by 16 inches once the half inch margin is taken off each edge.
Check the template rather than trusting it
Being the common size does not mean every template matching the description is correct. Template libraries are full of layouts described as tabloid that are actually built to some other proportion, and a few are built with bleed baked in, which is exactly what MakeMyNewspaper will not accept. Before you spend hours on a layout, open the document settings and confirm the page is genuinely 11 by 17 with no bleed set.
If it is not, change it before you start rather than after. Resizing a finished layout reflows text, moves every image and generally costs more time than starting again at the right size.
Comfortable for real newspaper layouts
Ten inches of printable width across five columns gives lines of about two inches, which is close to the classic newspaper measure and reads well at nine or ten point. Six columns tightens it further if you want more words on the page. This is the size where standard newspaper design conventions work without adaptation, which is not true of the near square 11 by 12 or the very tall broadsheet.