Japanese Era Converter

Convert Gregorian and Japanese era years

Convert from a Gregorian year to Japanese era years, or from an era year to Gregorian, using official eras from Taika through Reiwa. The converter handles mid-year reforms and the separate Southern and Northern Court era systems.

Gregorian to Japanese era

1. Select “Gregorian → Japanese Era.”
2. Enter a Gregorian year.
3. Select “Convert” to see every era and era year used during that Gregorian year.

Japanese era to Gregorian

1. Select “Japanese Era → Gregorian.”
2. Choose an era from the searchable era dialog.
3. Enter the era year as a number. Enter “1” for the first year.
4. Select “Convert” to see the Gregorian year.

About year-level conversion

This tool converts by year, not by month and day. When an era changed during a Gregorian year, both the old and new eras are shown. Ancient periods without an official era are reported as gaps instead of being treated as a continuation of the preceding era.

Data

Era names follow the National Diet Library bibliography for Japanese eras from Taika through Reiwa. Inclusive start and end years were checked for year-level conversion, including same-year reforms, the Southern and Northern Courts, and ancient gaps. Unofficial or disputed eras are kept separate as reference information in the selection dialog.

FAQ

Why are both Heisei and Reiwa shown for 2019?

This is a year-level converter. Japan changed from Heisei to Reiwa during 2019, so both Heisei 31 and Reiwa 1 are shown. The same applies to reform years such as 1912, 1926, and 1989.

Why do some years show no era?

Official era names were not used continuously in some ancient periods. The converter reports that no official era is recorded instead of extending the preceding era into those gaps.

How is the Nanboku-cho period shown?

The Southern and Northern Courts used different era names, so the converter labels and displays each court separately.

Can this tool determine the exact reform date?

No. This tool converts at the year level. If an era changed during a year, all eras used in that year are shown. Consult historical or official sources for exact reform dates.

How do I enter the first year of an era?

Enter “1” as the era year. Japanese results display it as 元年.

Is my input uploaded?

No. Selection and conversion run locally in your browser, and entered years are not sent to a server.