Use era-year-month-day input for era-to-Gregorian validation.
Japanese Era ⇔ Gregorian
Convert between Japanese era and Gregorian dates with year-month-day precision
Local Processing Only
Era to Gregorian (date conversion)
Enter era, year, month, and day to find the corresponding Gregorian date.
Result
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Enter era, year, month, and day
Gregorian to Era (date conversion)
Enter a Gregorian date to identify the era year. Supports all eras from Taika (645-06-19) onward.
Result
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Enter Gregorian year, month, and day
Era Boundary Notes
- Reiwa: starts on May 1, 2019
- Heisei: starts on January 8, 1989
- Showa: starts on December 25, 1926
- Meiji: starts on January 25, 1868
- Taiho: starts on March 21, 701
- Taika: starts on June 19, 645
How to Use
Use Gregorian date input to resolve the matching era and year index.
Test boundary behavior with sample era-change dates.
Use notes for out-of-range and boundary-day checks before filing.
FAQ
How far back does Gregorian-to-era conversion support?
It supports eras from Taika (June 19, 645) onward.
Why do I see 'out of valid range' in era-to-Gregorian mode?
The entered era year/month/day is outside that era's official date range.
Are era boundary days handled correctly?
Yes. Boundary days are compared by full date and annotated when relevant.
How is zodiac calculated?
The zodiac is calculated from the Gregorian year.
Is my input uploaded?
No. Conversion runs locally in your browser.
Does changing the reference date change the result?
Yes. Age and day-difference results depend on the reference date. When comparing, keep the reference date the same.
Why does it say “invalid date”?
Dates that don’t exist (e.g., Feb 30, or Feb 29 on a non-leap year) will fail validation. Review your input and try again.
How are era change boundary dates handled?
The era changes on the official change date. For formal documents around boundaries, do a quick manual check of the output.
References
- Cabinet Secretariat: Japanese Era Information
Official era operation and era-change reference.
- e-Gov Legal Search
Primary legal and administrative date references.
- NDL Research Navi: Japanese Eras
Reliable historical-era index for verification.
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