During World War II, the average Japanese soldier was considerably smaller than the average American Marine. Japanese soldiers averaged about 5 feet 3.5 inches in height and 115-120 pounds in weight, while American Marines averaged around 5 feet 7 inches in height and 140-150 pounds in weight, according to Quora. This difference in size likely impacted various aspects of combat, such as carrying capacity and hand-to-hand combat effectiveness.