https://en.wikipedia.org/wiki/European_comics
European comics are comics produced in Europe. The comic album is a very common printed medium. The typical album is printed in large format, generally with high quality paper and colouring, commonly 24x32 cm, has around 48–60 pages, but examples with more than 100 pages are common. While sometimes referred to as graphic novels, this term is rarely used in Europe, and is not always applicable as albums often consist of separate short stories, placing them somewhere halfway between a comic book and a graphic novel. The European comic genres vary from the humorous adventure vein, such as The Adventures of Tintin and Asterix, to more adult subjects like Tex Willer, Diabolik, and Thorga
The European, American, and Japanese comics traditions have followed different paths. Europeans have seen their tradition as beginning with the Swiss Rodolphe Töpffer from as early as 1827 and Americans have seen the origin of theirs in Richard F. Outcault's 1890s newspaper strip The Yellow Kid, though many Americans have come to recognize Töpffer's precedence. Japan has a long history of satirical cartoons and comics leading up to the World War II era.
https://makingcomics.spiltink.org/pgtemplates/
European comics typically come hard bound, and 21×30 cm. That’s 21 : 29
Most Belgian and European comics/BD are published in this format. It’s widely used around Quebec as well. And it provides for a bit more variety of page layout I think. it’s not quite as tall as the american comics dimensions, but often printed larger so really think of it as wider. Makes for great cinematic panels. and diversity in page flow. ED: It’s been a while since i made that but as I recall I found the measurements looking up online and cross checking against BD that I own, if you’re publishing with a printer used to the format check with them for their pref, but otherwise think it’s still fairly accurate? FYI for this and all the others outside of the US standard for which I own preprinted examples, I extrapolated the bleed and safe areas based on general printing averages. Bleed is always an additional 0.125″, or .25″ in total page width. And safe is about the same inside the crop line really but 1 cm or .5″ is typically about comic page margins but your millage may vary. I like using a wider margin myself.
