Edo bakufu, by reducing the length and the width by 1 bu while increasing the depth by 2 bu, wanted to trick the people into believing that the volume did not change, and the bakufu tried to conceal that the volume of the masu in real increased by about 3.7 percents, a theory says.
一説には、縦横が1分減り、深さが2分増えたのだから体積は変わらないと思わせて、実は体積が約3.7％増えているという策略であるとも言われる。