Lettering Has to Fit the Drawing
A comic page is a tightly arranged picture, not a blank sheet of text. Letterers place words inside speech balloons, where each line must fit the balloon’s shape without covering a face, gesture, or important detail. Uppercase letters share a consistent body height, so lines can be packed into a neat block with predictable spacing. That makes it easier to shape dialogue around the art.
Lowercase letters vary more: some rise above the main line, while others—such as g and p—drop below it. Those extensions can make neighboring lines feel crowded, especially when lettering is small. All caps avoid those descenders and give the letterer a simpler pattern to space.
A Practical Convention, Not a Rule
Comic lettering is often drawn or carefully arranged rather than set like ordinary book text. The letterer must balance clarity with the limited room in each balloon, and consistent uppercase forms help keep that work orderly. The convention also holds up when a page is reduced for printing: the words remain a compact, even texture within the artwork.
It is not the only workable choice. Some comics use lowercase or mixed-case lettering for a different visual feel, and digital tools make it easier to adjust type and spacing. But all caps remain a practical fit for a medium where every line has to share space with the picture.
