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12.6. What Western dates correspond to what Japanese dates?

Try the FAQ's western to Japanese year converter:

To convert a date from the Japanese era to a Western date, add the number in the `Add' column to the Japanese year. So, for example, Shōwa 25 is 1950.

Here is a table of recent eras. For a complete list, see 12.6.1. Complete list of Japanese eras.

The Japanese government started using the Gregorian calendar in Meiji 6. So the day before January 1 of Meiji 6 was not December 31 of Meiji 5, but December 2 of Meiji 5. The Japanese government started using the Gregorian calendar on 9th November 1872.

Luni-solar calendar

The Japanese traditional calendar was on a luni-solar principle, which was taught by China. In the Chinese lunar calendar, a year consisted of 12 months, or about 354 days, but it should have started about the same season every year. In order to satisfy the constraints, an extra month was inserted about every three years. Since the beginning of a month should have to meet to the new moon, and the season must not change drastically, the calendar became very complicated.

Old calendar in Japan

Ancient Japan imported the Chinese lunar calendar. I cannot find any reference on when it was imported, but I guess it may be before 7th century. In the older epoch, for example in the 3th century, Japan was said to count years by observing the seasons.

In 864, Japan adopted one of the Chinese calendars in which a year was defined as 365.2446 days. This calendar was used until 1699. Meanwhile in China, a more accurate calendar was invented, where a year was defined as 365.2425 days, just the same as the Gregorian calendar. Because of the error in the former calendar the season drifted slightly, so in 1700 Japan invented her own calendar based on her own astronomic observations. The principle, however, was the luni-solar one,the same as the Chinese one.

Solar calendar in Japan

In 1868, the Meiji Emperor took back the ruling power from the Tokugawa Shogun (the Meiji Restoration). Many regimes were reformed learning Western fashions. At the end of 1873, the government announced the adoption of the Gregorian calendar. It is said the true reason was from financial needs. The year was the first one where an extra month was inserted after the Meiji Restoration. Since the government paid salaries on a monthly basis to public servants (in the Tokugawa period the salary was paid on a yearly basis), the thirteenth salary should have been paid this year, but the government had no income for the payment. So, it adopted the solar calendar to terminate the year at the twelfth month.

Anyway, since that period, the Japanese official calendar has been the Gregorian, but some people still use the old calendar even now. It is not that the old calendar is rational. Since agriculture depends on the sun's movement, the solar calendar should be better than the luni-solar one. However, in the old calendar New Year and Summer Festival are at the non-busy seasons, but not in the Gregorian one. Many festivals, such as Peach, Iris, Star and Chrysanthemum, shift to improper seasons in the Gregorian calendar. For these reasons, the old calendar has not been thrown away.

Nengo

"Nengo" means the name of the era. In Western countries, the name of era is unique, i.e. Anno Domini. In old China (Korea and Japan), the name of era was changed for many reasons; enthronement, war, plague, eclipse etc. Japan did not adopt Chinese nengo, but invented her own ones. The usage of nengo was considered to be culturely loyal to the creator of the nengo. In this sense, Japan had not been the vassal of China culturally. The oldest nengo in Japan is Taika, which started from 645 A.D.

At the Meiji Revolution, the government determined that the "nengo" should be renewed on the day of the emperor's enthronement. Since then, only 4 nengo have existed; Meiji, Taisho, Showa and Heisei, which correspond to the emperors with these names (the current emperor is never called the Heisei Emperor, but will be called so after his death). For your information, Meiji 1, Taisho 1, Showa 1 and Heisei 1 correspond to 1868, 1912, 1926 and 1989, respectively. Please note that 1989 is Showa 64 before the enthronement (January 7) and Heisei 1 after it.

Imperial Calendar

There is another name of the era, the so-called Imperial Calendar. The Imperial Calendar is said to have started at the year of the enthronment of the first Emperor Jimmu. The year was defined as 660 B.C., thus the year in the Imperial Calendar can be calculated by adding 660 to the year of the Gregorian Calendar. It is not believed that the origin of the Imperial rule is so old. It might have started in the 4th century.

Eto

Twelve animals of Chinese New Year
Illustration credit: Márcia Novais
Used under a Creative Commons licence.

To explain "Eto", the Chinese zodiac, I must say that there are two sets of ordinal numbers used from long ago in China and East Asia. Years have been counted using a dyad made of numbers from the sets. One sequence consists of ten characters which are explained as elementals; elder wood, younger wood, e. fire, y. fire, e. earth, y. earth, e. metal, y. metal, e. water and y. water. The explanation was added afterwards and the original meaning was different. Another sequence consists of twelve characters which are explained as animals: rat, ox, tiger, rabbit, dragon, snake, horse, sheep, monkey, bird, dog, and wild pig. The original meaning had nothing to do with animals either.

Each year (and day) are named as the combination of two characters, each of which is taken from one of two sets. So, there are 60 combinations used to represent a year. See also 12.6.2. What is the Jikkan jūnishi?.

The usage of "eto" has long history. In ancient historical records, only eto was used to represent a year, so that historians may have to guess which year a record refers.

Eto is not used in the original form in contemporary Japan, only the animal part is used. For example, in the "dog" year, many New Year's greeting cards have pictures or drawings of dogs. Some people take the animals of their birth year into account in fortune telling.

Acknowledgements

Edited from posts by Funatsu Kunihiro and NAKANO Yasuaki. Thanks to Bart Mathias and muchan for filling in some of the names above.

Sub-pages

• 12.6.1. Complete list of Japanese eras
• 12.6.2. What is the Jikkan jūnishi?

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• Next article: 12.7. What are the old Japanese units like shaku?

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