Japanese Era Names: Meiji to Reiwa Exact Dates

The five modern era names run from 1868 to the present day

An era name, or gengo, is the year label Japan uses alongside the Gregorian calendar. The Era Name Act keeps the rule short: an era name is set by cabinet order, and it changes only when the throne passes to a new emperor. That one-era-per-reign arrangement was laid down at the start of Meiji, which is why the five modern names in the Japanese calendar line up with five reigns.

Meiji is the one entry without a clean first day. The edict issued in the ninth month of 1868 renamed the whole of Keio 4 as Meiji 1 and set the one-era-per-reign rule at the same time, so Meiji 1 covers that entire year rather than opening on a particular date inside it.

The other four rows do start on a named day, and that is where most conversion mistakes come from. Each of those days was fixed by a document: an imperial edict for Taisho and Showa, a cabinet order for Heisei and Reiwa. The two kinds of document place the boundary differently, and the next two sections take them in turn.

Taisho and Showa began on the day the previous emperor died

The two prewar transitions worked the same way. Emperor Meiji died on July 30, 1912, and an edict issued that day declared July 30 and everything after it to be Taisho 1. Emperor Taisho died on December 25, 1926, and an edict issued that day did the same for Showa 1.

For a dated document, the boundary sits inside the day itself rather than at the start of a later one. December 25, 1926 is not the tail end of Taisho 15; it is the first day of Showa 1.

The National Archives of Japan holds both signed edicts, and the note accompanying each states the rule in a single line. That wording matters for anyone reading a date from this period, because it fixes the change to a named day rather than to a year. An entry written on July 30, 1912 belongs to Taisho 1 even though almost seven months of that Gregorian year had already run under Meiji 45.

Heisei and Reiwa began the day after the order took effect

The two most recent transitions moved the boundary by a day. The cabinet order changing the era name to Heisei takes effect on the day after promulgation, and it was promulgated on January 7, 1989. Heisei 1 therefore opens the next day, and the prime minister's statement at the time put it plainly: the new era name applies from January 8.

Reiwa follows the same pattern for a different reason: its cabinet order takes effect the day after the abdication law came into force, and that date was April 30, 2019. Heisei closes on April 30 and Reiwa opens on May 1. The trigger this time was an abdication rather than a death, but the one-day gap between the order and the new era is the same.

Four Western years hold two era names each

Because each of those transitions landed mid-year, four Gregorian years are split between two eras. When a document falls in one of them, the year alone will not tell you which era name belongs on it — the month and day decide.

The four Western years that contain two Japanese era years

Year	Old era	New era
1912	Meiji 45 through July 29	Taisho 1 from July 30
1926	Taisho 15 through December 24	Showa 1 from December 25
1989	Showa 64 through January 7	Heisei 1 from January 8
2019	Heisei 31 through April 30	Reiwa 1 from May 1

The first year of an era is written 元年 (gannen) instead of with the numeral 1, so a colophon reading 昭和元年 and one reading 昭和二年 are consecutive years. Going the other way, from a Western year to the era name and its number, is a different lookup. Japanese era name to Western year, with a table lists the two side by side, year by year.

Adding the offset converts the year number, and nothing else

The arithmetic runs both ways: add the offset to the Japanese year to get the Western year, or subtract it to go back. Showa 25 is 25 + 1925 = 1950. Reiwa 8 is 8 + 2018 = 2026.

What the offset does not carry across is the month and day. In the four split years above, the same arithmetic returns a plausible Western year for two different era names, and only the date settles which one you should have used: Heisei 31 + 1988 and Reiwa 1 + 2018 both come to 2019.

Two related pages pick up where this one stops. Reiwa year to Western year, with a table gives the current era year by year. When the Japanese year in front of you is a date of birth, Japanese calendar year to age: a birth date guide carries it through to an age.

Showa 64 is a year number, not the length of the era

Each era stops at a different year number: Meiji 45, Taisho 15, Showa 64 and Heisei 31 are the highest ones that exist. A document dated Taisho 16 or Heisei 32 contains an error, so those highest numbers give you a quick check when you are reading handwritten dates.

The mistake is reading those numbers as durations. Showa 1 began on December 25, 1926 and the era's final year ended on January 7, 1989, so neither the first year of Showa nor the last is a full one: each ran seven days, counting both ends. The number 64 names a year, not a count of how long the era lasted.

Dates before Meiji 6 follow the lunisolar calendar

Japan changed calendars in the middle of this era. The edict of the eleventh month of Meiji 5 abolished the lunisolar calendar and adopted the solar one. It fixed December 3 of Meiji 5 as January 1 of Meiji 6, and moved the country to 365-day years with a leap year every fourth year.

The offset table still converts year numbers for the early Meiji years, but the months and days printed beside them are not Gregorian. A record dated in the tenth month of Meiji 3 does not sit in October 1870, and reading it that way will move the date by weeks. Which year format a Japanese document should carry in the first place is a separate question, and Japanese Era in Business Documents: What to Use takes it up.

Reiwa gets no number here, because the count is contested

English sources often give Reiwa a position in a numbered sequence. The Japanese government publishes no such number, and the count itself is contested: for fifty-six years in the fourteenth century there were two rival imperial courts, each with its own era names, so the total depends on which side is counted.

The government's own wording stays deliberately loose. The prime ministerial statements at the two most recent transitions put the practice at more than thirteen hundred years old, and close to fourteen hundred, without ever giving a count of the names themselves.

This page keeps to the five modern eras for a matching reason. Those five are the ones whose first and last days are fixed by an edict or a cabinet order you can read.

In an era date, the month and day decide the era

Three things carry most of the weight when you read a date written in Japanese era names. Transitions happen mid-year, so 1912, 1926, 1989 and 2019 each hold two era names, and the month decides between them.

The offset converts the year number and nothing else, so in those four years the arithmetic returns a plausible answer for either era. Anything before January 1 of Meiji 6 sits on the lunisolar calendar, where there is no Gregorian month and day to match.