Convert Japanese era years (Reiwa, Heisei, Showa, Taisho, Meiji) to Gregorian years and back locally - e.g. Reiwa 7 = 2025. No upload.
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
Japan counts years not only by the Gregorian calendar but also by the era (nengo) of the reigning emperor - official forms, ID documents, contracts and receipts very often carry an era year like "Reiwa 6" instead of "2024". This tool converts in both directions: from a Gregorian date to the matching Wareki date, and from an era, year, month and day to the Gregorian date.
The conversion runs entirely locally in your browser, in pure JavaScript - nothing is uploaded and nothing is stored. The Gregorian-to-Wareki direction uses the Japanese calendar calculation built into the browser, the same technology Japanese operating systems use - including the special "gannen" naming for an era's first year (e.g. "Reiwa Gannen" instead of "Reiwa 1"). The Wareki-to-Gregorian direction additionally checks whether the chosen era was even valid yet (or still valid) on that day, and honestly reports an impossible case (for example a month before the era actually began) instead of inventing a wrong year.
An honest note: the five eras since 1868 are supported (Meiji, Taisho, Showa, Heisei, Reiwa); the era boundaries are the actual historical transition days, not rounded year numbers. Reiwa currently has no end date because it is the ongoing era. This tool is not meant for older Japanese calendar forms (before 1868).
| Input formats | Form inputs (no file) |
|---|---|
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: Covers the five eras since 1868 (Meiji, Taisho, Showa, Heisei, Reiwa) by their actual historical transition days - no rounded year numbers and no support for older Japanese calendar forms before 1868. An era/year/month/day combination that never historically existed (for example a month before that era actually began) is honestly reported as invalid instead of showing a wrong date.
No. The conversion runs entirely locally in the browser (pure JavaScript); nothing is sent or stored.
"Gannen" means "first year" - the first year of any era carries this name instead of the number 1, so "Reiwa Gannen" instead of "Reiwa 1".
On 1 May 2019, with the accession of Emperor Naruhito. The day before, 30 April 2019, was still Heisei 31.
The tool shows an honest dash instead of a wrong date - for example when a month is chosen that lies before the era actually began.
Meiji (1868-1912), Taisho (1912-1926), Showa (1926-1989), Heisei (1989-2019) and Reiwa (since 2019) - the five eras with their actual historical transition days.
Date Difference Calculator · Working Days Calculator · Unix timestamp