Length is shorter than shoulder length, but no longer than the knee. zettai ryouiki:
"Zettai Ryouiki" ("Absolute Territory" in English) describes the area of uncovered thigh between the skirt and the stockings. The presence of zettai ryouiki requires socks that go above the knees. The golden ratio for the ultimate zettai ryouiki is 4:1:2.5 (length of skirt : zettai ryouiki : length of socks above knee) and the acceptable margin for error is ±25％. school uniform:
Japan introduced school uniforms in the late 19th century. Today, school uniforms are almost universal in the Japanese public and private school systems. They are also used in some women's colleges. The Japanese word for uniform is seifuku (制服). In the majority of elementary schools, students are not required to wear a uniform to school. Where uniforms are required, many boys wear white shirts, short pants, and caps. Young boys often dress more formally in their class pictures than they do other days of the school year. Girls' uniforms might include a gray pleated skirt and white blouse. Occasionally the sailor outfit is used for girls. The uniform codes may vary by season to work with the environment and occasion. It is common for both boys and girls to wear brightly colored caps to prevent traffic accidents. Also, it is normal for uniforms to be worn outside of school areas. This is going out of fashion and many students are wearing casual dress. The Japanese junior- and senior-high-school uniform traditionally consists of a military style uniform for boys and a sailor outfit for girls. These uniforms are based on Meiji era formal military dress, themselves modeled on European-style naval uniforms. The sailor outfit replace the undivided hakama (andon bakama 行灯袴) designed by Utako Shimoda between 1920–30. While this style of uniform is still in use, many schools have moved to more Western-pattern parochial school uniform styles. These uniforms consist of a white shirt, tie, blazer with school crest, and tailored trousers (often not of the same color as the blazer) for boys and a white blouse, tie, blazer with school crest, and tartan culottes or skirt for girls.