Japanese Era Date Converter
Convert Gregorian dates to Japanese era notation or back, respecting the exact transition dates between eras.
Starts with an editable example. Replace the dates and rules with your own.
Your calculation
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Choose your dates.
Select your counting rules and calculate.
Calculation details
| Step | Value |
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How to use this calculator
Enter a Gregorian date or select the era, era year, month and day. Year one is also called gannen.
Coverage is Gregorian 1900-2100 and includes Meiji, Taisho, Showa, Heisei and Reiwa. Gregorian month and day rules apply. Reiwa is extended prospectively until a future era announcement updates the table.
A worked example
April 30, 2019 is Heisei 31. May 1, 2019 is Reiwa 1, the first day of that era.
Can Reiwa 1 include January 2019?
No. The Reiwa era began May 1, 2019. A date before that transition is rejected for Reiwa 1.
Which calendar and years are supported?
Each result states its calendar, time scale, precision and supported range. Batch converters accept up to 100 nonempty input lines and retain invalid rows. Copy, CSV and print include the calculation rules. Calendar downloads appear when a result contains dated events. Calculations run in your browser; no reminders or jobs are scheduled.
What happens to my dates?
Calculations run on your device. Saving a calculation is optional and keeps it in this browser. A setup link contains the dates and settings you entered; anyone with the link can read them. Use one tab per saved calculator. Clear saved data from Privacy & settings.