Tsubo (written 坪) is a Japanese unit of area. Conversion conventions in place since 1891 state that 1 Tsubo is equivalent to 400/121 meters2 equating to 3.306m2. In terms of Japanese measurements, 1 Tsubo is twice the size of 1 Jō, it is equivalent to one square ken or 36 square shaku (units of length). It is the base unit of area measurement.