From the time of Taiko kenchi through the Edo period, the economic value of all kinds of land such as rice (or vegetable) field and residential area, was converted into the productivity of rice, and the productivity, whose unit was koku, was calculated by multiplying the land size by a fixed figure called kokumori (land's productivity per 'tan' [a Japanese area unit]).
太閤検地以後江戸時代を通じて、田畑や屋敷などの土地の価値に至るまで、面積に石盛という一定の計数をかけて米の生産力に換算して石単位で表示するようになった。