Kokudaka (The Figure Of Land Productivity) (石高)
Kokudaka refers to the figure of land productivity shown with koku (a unit), which was used in the early modern ages of Japan. Taxation on land was implemented according to kokudaka from the time of Taiko kenchi (the land survey by Hideyoshi TOYOTOMI) until the land-tax reform in the Meiji period. And so, kokudaka also showed the income of daimyo (Japanese territorial lords) and that of hatamoto (direct retainers of bakufu [Japanese feudal government headed by a shogun]).
Summary
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]). This was called kokudaka system, and the output of crops other than rice and seafood was converted into the output of rice of the same economic value as those products. Kokudaka was used to show the income of samurai including daimyo gained from their territory, and to show the retainers' salary given from the lord as well. Kokudaka system is sometimes called 'hyakusho takashoji' (system to measure the property of a farmer with kokudaka) when mentioned for the farmer, or called 'kokudaka chigyo system' (system to measure the annual stipend of a samurai with kokudaka) when mentioned for samurai (especially daimyo). Kokudaka system lasted until the land-tax reform in the Meiji period.
1 koku was equal to the amount of rice consumed by an adult man in a year, so if 1 koku of rice is equated with the reward for a soldier, the kokudaka multiplied by the rate of nengu (land-tax) implies the number of soldiers fed. In other words, kokudaka showed not only the financial power but also the troop strength of Sengoku daimyo (Japanese territorial lord in the Sengoku period). The order of military service issued by bakufu in the Edo period enforced daimyo to mobilize about 200 people (including noncombatants) for every 10,000 koku of omote-daka (kokudaka officially recognized by the Edo bakufu).
Kokudaka of daimyo
The following is only the figure officially recognized by the Edo bakufu (omote-daka) of local domains, and their uchi-daka (real figure of rice harvest) was quite different from their omote-daka in many cases. For details, please refer to the article of Uchi-daka.
The figure as of the last days of the Tokugawa shogunate
The special status family: The Tokugawa Shogun family in control of the Edo bakufu
4 million koku of tenryo (bakufu-owned land), including Hida Province and Kai Province. (This figure does not include 3 million koku of kokudaka, gained from the fiefs of hatamoto, including kotai-yoriai (the hatamoto which had alternate-year residence in Edo).
The first rank: The Maeda clan in Kaga Domain
It ruled three provinces such as Kaga Province, Noto Province, and most of Etchu Province.
It was based at Kanazawa-jo Castle in Kaga Province (today's Kanazawa City);
The kokudaka was 1.025 million koku.
The second rank: The Shimazu clan in Satsuma Domain
It ruled Satsuma Province, Osumi Province, a part of Hyuga Province, and Nansei Islands. It was based at Kagoshima-jo Castle in Satsuma Province (today's Kagoshima City). The kokudaka was 0.77 million koku.
The third rank: The Date clan in Sendai Domain
It ruled a part of Mutsu Province. It was based at Sendai-jo Castle in Mutsu Province (today's Sendai City). The kokudaka was 0.625 million koku.
The fourth rank: The Owari Tokugawa family in Owari Domain
It ruled Owari Province, Mino Province and a part of Shinano Province. It was based at Nagoya-jo Castle in Owari Province (today's Nagoya City). The kokudaka was 0.62 million stones.
The fifth rank: The Kishu Tokugawa family in Kishu Domain
It ruled Kii Province, the southern part of Ise Province, and a part of Yamato Province. It was based at Wakayama-jo Castle in Kii Province (in today's Wakayama City). The kokudaka was 0.555 million koku.
The sixth rank: The Hosokawa clan in Kumamoto Domain
It ruled most of Higo Province. The kokudaka was 0.54 million koku.
The seventh rank: Fukuoka Domain
0.47 million koku
The eighth rank: Hiroshima Domain
0.43 million koku
The ninth rank: Choshu Domain
0.37 million koku
The 10th rank: Saga Domain
0.36 million koku
The 11th rank: Hikone Domain
0.35 million koku
The 12th rank: Mito Domain
0.35 million koku