How much is one koku worth?

One koku was approximately 180 litres (about 150 kg) of rice — theoretically enough to feed one adult for one year. In Edo economic terms, one koku of rice was roughly equivalent to one ryo of gold, though the exchange rate fluctuated. A low-ranking samurai might receive 20-50 koku annually; senior retainers earned hundreds or thousands.

Why were domains measured in koku?

Rice production was the economic foundation of feudal Japan. A domain's koku rating measured its agricultural output — which directly determined how many soldiers it could field, how many retainers it could pay, and what military obligations it owed the shogunate. Measuring domains in koku provided a universal standard for the entire feudal hierarchy.

Koku: Japan's Feudal Unit of Rice and Power

The koku (石) was the unit that measured feudal Japan. Land, rank, salary, military obligation — everything was expressed in rice.

What a Koku Was

One koku was approximately 180 litres of dry rice — about 150 kilograms. The standard calculation held that one koku would feed one adult for one year. This made it both a measure of volume and a shorthand for economic subsistence. [history]

The koku system was standardised across Japan by Toyotomi Hideyoshi’s taiko kenchi (太閤検地) — the great land survey he conducted from 1582 to 1598. Survey teams measured agricultural land throughout Japan, assessed its productive capacity, and assigned standardised koku values. The resulting kokudaka (石高) ratings became the economic foundation of the Edo period’s entire feudal hierarchy. [history]

How Domains Were Rated

A lord’s power was expressed in koku:

A daimyo was defined as holding a domain assessed at 10,000 koku or more
The Tokugawa shogunate’s direct holdings were assessed at approximately 4 million koku — by far the largest in Japan
Major outside lords (tozama daimyo) like the Maeda of Kaga held over 1 million koku
Small daimyo might hold exactly 10,000 koku — just enough to qualify [history]

The koku rating determined military obligation. The shogunate could calculate how many soldiers each domain owed for national campaigns based on its rice assessment. The system made military capacity visible and standardised across Japan.

Samurai Salaries

Samurai were paid in koku — either as actual rice delivered to their warehouses, or in a cash equivalent based on the prevailing rice price. [history]

Typical ranges in the Edo period:

Low-ranking samurai (gokenin, minor retainers): 20-50 koku
Middle-ranking retainers: 100-500 koku
Senior retainers and senior officials: 1,000+ koku
Hatamoto (direct Tokugawa retainers with audience rights): typically 100-10,000 koku

The gap between a 20-koku foot soldier and a 5,000-koku senior retainer was enormous — both were technically “samurai,” but their lives bore little resemblance to each other.

The Problem in the Edo Period

As Japan’s money economy developed in the Edo period, the koku system created structural problems. Samurai were paid in rice, but lived in cities where they needed to buy things with coin. They sold their rice stipends to merchants — often at disadvantageous rates — and accumulated debt. [history]

The great merchants of Osaka and Edo grew rich managing this conversion. Many samurai families fell into chronic debt to merchant houses. The fixed koku stipend became a poverty trap as prices rose and the rice economy increasingly gave way to commerce.

This structural tension was one of several pressures that made the Edo social system increasingly unworkable by the 18th and 19th centuries — and contributed to the conditions that made Meiji modernisation possible.