Ōban is the ukiyo-e print format measuring approximately 38 by 26 centimeters.
The ōban, meaning “large format,” became the standard size for many full-sheet ukiyo-e prints. Its proportions gave artists enough space for actor portraits, beautiful women, landscapes, and narrative scenes while remaining convenient for commercial production and display. Exact measurements vary because paper was trimmed and publishers used slightly different dimensions.
The format should not be confused with chūban, a smaller medium-sized sheet, or hosoban, a narrow format often associated with actor prints. Ukiyo-e sizes are usually described by Japanese format names rather than by a single rigid international measurement, so catalogues may list slightly different dimensions for apparently identical formats.