Cho (a unit of length in old Japanese system of weights and measures) (町 (単位))
Cho is a unit of length (distance) or area in old Japanese system of weights and measures.
Unit of Length
In this case, cho (町) is also written as 丁 in Chinese characters. In Jorisei (system of land subdivision in ancient Japan), 6 shaku (unit of distance approximately equal to 30.3 centimeters) was 1 bu (歩; a unit of land measurement) and 60 bu made up 1 cho: However, at Taiko kenchi (the land survey by Hideyoshi TOYOTOMI), 1 cho became 60 ken (unit of distance, approximately 1.818 meters) with 1 ken being 6 shaku and 3 sun (a unit of distance, approximately 3.03 centimeters) but later with 1 ken equals to 6 shaku. In 1891 after Japan signed the treaty of the meter, 1.2 kilometers was defined as 11 cho based on meters. That means that 1 cho is approximately 109.09 meters, and 1 kilometer consists of approximately 9.1 cho.
Unit of Area
To distinguish it from cho as a unit of length, it is sometimes called 'chobu.'
A 10th of 1 cho is called tan using two different kanji or Chinese characters, '反' or '段.'
In Jorisei, an area of a square with sides of 1 cho was considered as 1 cho (chobu) (As 1 cho was 60 bu, the area was 3600 bu). At Taiko kenchi 1 cho was changed to 3000 bu (tsubo; a unit of land measurement; 3.31 square meters). In 1891 after Japan signed the treaty of the meter, 120 hectares was defined as 121 cho. This means that 1 cho is approximately 0.9917 hectares (9917 square meters) and 1 square meter is approximately 100.83 cho. As 1 cho is very close to 1 hectare, Japan's transfer to the metric system in terms of areas went smoothly.