Calendars: Japanese Emperor Date

The traditional Japanese calendar consists of eras based on the reigning emperors. The imperial date format is required for some government documents and applications. For example, until Jan 1, 2002, the Japanese patent office used emperor dates.

This page gives you the Unicode character values, emperor era names and the layout information you need to produce a Japanese emperor date and to convert from a western calendar.

Imperial dates are formatted with the name of the era followed by year, month, and day.
The Japanese characters for year (, U+5E74), month (, U+6708) and day (, U+65E5) are used as separators. Today's date, "2003-01-24" (ISO 8601 yyyy-mm-dd) might therefore be written in Japanese western style as "2003年1月24日", and in Japanese imperial style as "平成15年1月24日".
The year 2003 is the 15th year of the era Heisei (平成), which began in 1989 as year 1.

Note: "U+hhhh" is notation for Unicode scalar value (i.e. code point) using hexadecimal digits. You can represent a character in HTML using the Unicode scalar value by writing it as &#xhhhh;.

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Also see: 六曜 ROKUYO – Lucky And Unlucky Days in Japan

Example Dates

Date StyleDate Example
AmericanJanuary 13, 2003
ISO 86012003-01-13
Japanese, western digits2003年1月13日
Emperor, western digits平成15年1月13日
Emperor, Kanji digits平成十五年一月十三日

Japanese Emperor Era (Nengo 年号)

Unicode Values EdictStart DateEnd Date
Akihito HEISEI 平成 or ㍻U+5E73, U+6210 or U+337B GENGOU O ARATAMERU SEIREI
(Government ordinance to change the name of era) issued on January 7th, 1989.
There is no overlap on dates between SHOWA and HEISEI.
Hirohito SHOWA 昭和 or ㍼U+662D, U+548C or U+337C SHOWA KAIGEN NO SHOUSHO
(Imperial edict to change the name of era SHOWA) issued on December 25th, 1926.

The language used in the edict is ambiguous whether December 25th is included or excluded in SHOWA. The word "IGO" can be interpreted as "after" or "from", so it is unclear whether SHOWA starts after December 25th or on December 25th. It is clear December 25th, TAISHOU 15 does exist.

Yoshihito TAISHOU 大正 or ㍽U+5927, U+6B63 or U+337D TAISHOU KAIGEN NO SHOUSHO
(Imperial edict to change the name of era to TAISHOU) issued on July 30th, 1912.

The language used in the edict (like SHOWA) is ambiguous whether TAISHOU starts after July 30th or on July 30th. It's clear July 30th, MEIJI 45 does exist.

Mutsuhito MEIJI 明治 or ㍾U+660E, U+6CBB or U+337E MEIJI KAIGEN NO FUKOKU
(Declaration of changing the name of era to MEIJI) issued on September 8th, 1868.
The declarations up to the MEIJI era, specify the name of the year, and there is no concept to start one era on a particular date of the year. So the first year of the MEIJI era entirely over-laps with the last year of KEIO (or KEIO 4).
  KEIO       1868

Note: The first year of each era is always referred as GANNEN, meaning the first year of era. For example, the first year of HEISEI is called HEISEI GANNEN, instead of HEISEI 1. The year number 1 is never used to indicate the first year of era.

According to Japanese legend, Emperor Akihito, is Japan's 125th imperial sovereign in an unbroken line from Emperor Jimmu, who ascended the throne in about 660 B.C. Japan's is the world's oldest existing hereditary monarchy.

Month Names
(Actually just numbers 1-12 followed by the character for month (月 gatsu)
Unicode Scalar ValuesU+6708 U+4E00U+4E8C U+4E09U+56DBU+4E94 U+516D
Month Names   一月 二月 三月 四月 五月 六月
Pronunciationgatsuichi-gatsu ni-gatsusan-gatsushi-gatsu go-gatsuroku-gatsu
  July AugustSeptemberOctoberNovemberDecember
Characters   十一 十二
Unicode Scalar Values  U+4E03U+516B U+4E5DU+5341 U+5341 U+4E00U+5341 U+4E8C
Month Names   七月 八月 九月 十月 十一月 十二月
Pronunciation  shichi-gatsu hachi-gatsuku-gatsujū-gatsu jūichi-gatsujūni-gatsu

Japanese days of the week are sometimes abbreviated to the single Kanji character, but are formally written as 3 characters, the first Kanji indicating the particular day and the next two Kanji (曜日 yōbi) for "day". So today is Friday, shortname and fullname 金曜日.

Japanese Days of the week
Characters曜 日
Unicode Scalar ValuesU+66DC U+65E5U+6708U+706BU+6C34U+6728U+91D1U+571FU+65E5
Day Names 月曜日 火曜日水曜日 木曜日金曜日 土曜日日曜日

Thanks to Takao Suzuki for the initial content of this page.

Related links:

六曜 ROKUYO – Lucky And Unlucky Days in Japan
Calendar & Telling Time
Years in Japan by era and sexagesimal name (Japanese) (English)
Shin Hanga Date Translation
Japan Inc. Japanese emperors
National Diet Library, Japan - Unriddling the Daisho-reki calendar
Japanese Calendar
Days of the week and months of the year in many languages
Data book of cultural convention in Asian countries -Dates (Good reference for many countries, with Unicode character values)
Can you tell me the old names of the months?