The Japanese (Shakkanhō) Area equation converts area in Japanese units to modern (Western) area such as meters2 based on conversion conventions in place since 1891.
The base unit of area in the Shakkanhō system is the Tsubo. The Tsubo and its denominations are equivalent to the following metric measurements:
The equation also includes the Bu (歩) which is used for agricultural measurements and is equivalent to 1 Tsubo.
Other Japanese units of measurement, such as those used for volume, may share the same names as the units used for area. Furthermore, since the Japanese language contains many homonyms some units for measuring length, volume, weight and mass, are romanized in the same manner as those above, but use different kanji (Chinese characters) to distinguish between them. One example is the Shaku, which when used to measure length is written with the character 尺.