Shakkanho (Traditional Japanese Units)
Shakkanho is Japan’s traditional system of weights and measures, based on the shaku for length and the kan for mass. Although Japan adopted the metric system, several shakkanho units — especially the tsubo and the go — remain in everyday use.
Convert
Main units and metric equivalents
The system covers length, area, volume and mass. One shaku is defined as exactly 10/33 of a metre, and one go is the everyday measure for rice and sake.
| Unit | Kanji | Metric equivalent |
|---|---|---|
| Length | ||
| sun | 寸 | 0.030303 m |
| shaku | 尺 | 0.30303 m |
| ken | 間 | 1.8182 m |
| chō | 町 | 109.09 m |
| ri | 里 | 3927 m |
| Area | ||
| tsubo | 坪 | 3.3058 m² |
| Mass | ||
| momme | 匁 | 3.75 g |
| kan | 貫 | 3.75 kg |
| Volume | ||
| gō | 合 | 0.18039 L |
| shō | 升 | 1.8039 L |
| to | 斗 | 18.039 L |
| koku | 石 | 180.39 L |
History
Shakkanho derives from ancient Chinese measures introduced via Korea, and was standardised under the ritsuryō system. After the Meiji era Japan progressively adopted the metric system, and shakkanho was officially superseded for trade in 1959, though it survives by custom.
Modern use
The tsubo (about 3.31 m²) is still standard in real estate and construction, and the jō (tatami mat) sizes rooms. The go (about 180 mL) and shō measure rice and sake, and the koku historically rated a domain’s rice yield.
Frequently asked questions
Is shakkanho still used in Japan?
Officially it was replaced by the metric system in 1959, but the tsubo (area), jō (tatami), go and shō (rice and sake) are still in everyday use.
How big is one tsubo?
One tsubo is about 3.31 m², roughly the area of two tatami mats. It is the standard unit for land and floor area in Japan.
What is a koku?
A koku is about 180 litres, the amount of rice once considered enough to feed one person for a year. It was used to rate the wealth of feudal domains.