Because a jo is approximately 1.67 ken (=10/6 ken) (ken is a measure of length), one hojo is about the size of a four-and-a-half-mat Japanese room (being approximately 1.5 ken on a side).
1丈は約1.67間（＝10/6間）であるため、1方丈は四畳半程度（四畳半の1辺は約1.5間）の広さである。