1. What Does the Phrase "Three Mon of Profit" Really Mean?
The phrase "three mon of profit" is often written with characters that mean "profit," but it actually refers to a spiritual or practical benefit, not just financial gain, according to educational materials from the Financial Education Center. [3] The value of 1 mon is estimated at 10 to 30 yen in modern terms. If you simply multiply by three, it is 30 to 90 yen, with 100 yen often used as a round figure for easy understanding. [3]
It is interesting that the value of 1 mon is given as a range of 10 to 30 yen, which is a three-fold difference. There is no single exact number because the exchange rates and types of money in Edo Japan changed over time. To understand why the numbers move so much, we must look at how people counted gold, silver, and copper coins.
2. How Did Edo People Use Gold, Silver, and Copper Money?
In the Edo period, there were three types of currency: gold, silver, and copper (called "mon"). Each had a different way of showing value. Gold coins, known as koban, were counted by number; one koban was counted as 1 ryō. Silver was measured by weight in units called monme (1 monme is 3.75 grams). Copper coins were counted individually, with 1 coin equaling 1 mon. [3]
The official exchange rate set by the government during the mid-to-late Edo period was: 1 ryō of gold = 60 monme of silver = 4,000 mon of copper. However, when people actually exchanged money, they used the market rates at that specific time. [3] Historical records from the Currency Museum show calculations using 1 ryō = 6,500 mon in the late Edo period, which differs from the official rate. [1]
This means that even the question "how many mon is 1 ryō?" changes depending on when you look at it. For ordinary people, the copper coin was the main currency in their wallets.
3. Which Coins Did Common People Carry in Their Wallets?
The main copper coin used by common people was the Kan'ei Tsuho. It was cast from 1636 to 1860 and remained in circulation until the early Meiji period. [5] There were different types: copper 1-mon coins, iron 1-mon coins, brass 4-mon coins, and iron 4-mon coins. These were produced in various locations across Japan. [5]
The Kan'ei Tsuho is said to have played a major role in the nationwide circulation of copper coins. [5] According to educational materials, the appearance of these unified copper coins helped form the shape of the three-currency system, described as "gold use in eastern Japan, silver use in western Japan, and copper coins for common people." [3] Because small copper coins worked everywhere, people could buy everyday items with ease.
To convert 1 mon into today’s money, we need to choose a "yardstick" or comparison item. Is it rice? Soba noodles? Or wages?
4. Why Is 1 Ryō Worth Either 40,000 Yen or 410,000 Yen Today?
If we measure 1 ryō by the price of rice, the Currency Museum uses a calculation based on the 18th century where 1 koku (about 150 kg) of rice equaled 1 ryō. If 5 kg of rice costs about 2,700 yen today (based on 2024 statistics), then 1 ryō would be worth about 81,000 yen. [1] However, other educational materials state that looking at rice prices in the mid-Edo period makes 1 ryō worth about 40,000 yen. [3] Even using the same item (rice), the value differs depending on the time period and source.
If we measure by soba noodles, a bowl of soba cost 16 mon in the mid-to-late Edo period. Using a rate of 1 ryō = 6,500 mon, you could buy about 406 bowls with 1 ryō. [1] Other materials estimate that looking at soba prices makes 1 ryō worth between 120,000 and 130,000 yen in the mid-Edo period. [3]
If we measure by wages, there is a record from the late 18th century where 1 ryō could hire 23 carpenters for one day. Today, a carpenter’s daily wage is about 18,000 yen (based on 2024 Ministry of Health, Labour and Welfare statistics). Multiplying this by 23 gives about 414,000 yen. [1]
The Currency Museum notes that the modern value of 1 ryō varies greatly depending on what you compare it to, and even the same item had different prices at different times in Edo Japan. [1] So, 40,000 yen and 410,000 yen are not one being wrong; they just use different yardsticks.
5. Is "50 Ryō" in Rakugo Stories Worth 2 Million or 6 Million Yen?
In rakugo (traditional comic storytelling), a large sum of money is often referred to as "50 ryō." According to educational materials, this amount is equivalent to two units of kirimochi (a type of rice cake used as a unit of currency). If you calculate 1 ryō as 40,000 yen, then 50 ryō is 2 million yen. If you calculate 1 ryō as 120,000 yen, it becomes 6 million yen. [3] The imagined value of the same story changes based on which yardstick the listener uses.
The "thousand-ryō box," a famous symbol of great wealth, also has a wide range. The modern value of the money inside is said to be anywhere from several million yen to around several hundred million yen. [3] This huge difference is not just about the yardstick; it also relates to the fact that the Edo period lasted for about 265 years, during which prices changed significantly.
6. How Did Prices Change During the 265 Years of the Edo Period?
The Edo period was long, lasting about 265 years, and prices fluctuated throughout that time. [3] For example, in autumn 1866 (Keio era), 1 koku of rice was valued at 585 monme of silver. Ten years earlier, in 1856 (Ansei era), the figure was 102 monme of silver. This is a difference of about six times. [4]
Meiji University Museum materials state that if you look at gold 1 ryō through the lens of rice prices, it might be worth about 10,000 yen in some contexts. However, they also note that because the value of money and goods differs between then and now, an exact conversion is not possible. [4] This 10,000 yen figure is very different from the Currency Museum’s 80,000 yen or the Financial Education Center’s 40,000 yen. Because the time periods and standards used are different, we cannot decide which single number is "correct."
Therefore, the answer to "how much is 1 mon today?" depends on what yardstick you use and which year in Edo history you are measuring. This is why it has a range of 10 to 30 yen.
7. How Can You Investigate Edo-Period Prices Yourself?
If you want to try this yourself, pick a food item you eat today and find its current price. Then, look at the Edo-period prices for that same item (the Currency Museum has examples for soba and sake). [1] Calculate how much 1 ryō would be worth if you used that food as your yardstick. If your answer for soba is different from your answer for sake, you have confirmed that the value changes depending on the comparison.
You can also read official information. The Bank of Japan Institute for Monetary and Economic Studies Currency Museum publishes materials showing the assumptions behind their calculations of Edo-period money. Pay attention to how they state their premises, not just the final numbers.