Japanese Era Year Converter (Wareki ⇔ Gregorian)
Convert between the Japanese era calendar (Meiji, Taisho, Showa, Heisei, Reiwa) and the Gregorian calendar, down to the exact day. Correctly handles era-boundary dates (e.g. Showa 64 = Jan 7, 1989 vs Heisei 1 = Jan 8, 1989) and shows the current age for the converted date. Everything runs in your browser — the date you enter is never sent anywhere.
The date you enter is processed entirely in your browser and never sent anywhere.
Enter a date and press "Convert".
- Gregorian date
- Japanese era date
- Age today
How to use
- Choose "Gregorian → Japanese era" or "Japanese era → Gregorian".
- For the Gregorian mode, enter year/month/day. For the Japanese era mode, enter the era, era year (1 for the first year), month, and day.
- Press "Convert". You'll see the converted date plus the current age if that date were a birth date.
How it works
Supported range
This tool covers the five modern Japanese eras — Meiji, Taisho, Showa, Heisei, and Reiwa — from January 25, 1868 (the start of Meiji) through December 31, 2100.
Era boundary dates used by this tool
- Meiji: Jan 25, 1868 – Jul 29, 1912
- Taisho: Jul 30, 1912 – Dec 24, 1926
- Showa: Dec 25, 1926 – Jan 7, 1989
- Heisei: Jan 8, 1989 – Apr 30, 2019
- Reiwa: May 1, 2019 – (ongoing)
The Meiji→Taisho and Taisho→Showa transitions happened on the very day the emperor died (same-day era change). The Showa→Heisei transition was different: Emperor Showa died on January 7, 1989, but the new era name took legal effect the next day, January 8. That one-day gap is a common source of mistakes, so this tool treats January 7, 1989 strictly as Showa and January 8, 1989 strictly as Heisei — combinations like "Heisei 1, January 7" or "Showa 64, January 8" are rejected as dates that never existed.
Because several years span an era change (e.g. Meiji 45 / Taisho 1, Showa 64 / Heisei 1, Heisei 31 / Reiwa 1), converting by year alone would be ambiguous — that's why this tool always asks for the full month and day.
About the age shown
The converted date is treated as a birth date, and the tool shows the current age (as of today) using the standard definition: you turn one year older on your birthday, not before. For people born on February 29, non-leap years use February 28 as the effective birthday — this matches common real-world practice in Japan.
FAQ
Is the date I enter sent anywhere?
No. All calculations happen entirely inside your browser; nothing is transmitted externally.
What does "era year 1" mean?
It's the first year of that era, commonly written as "Gannen" (元年) in Japanese. Enter "1" in the year field. For example, Reiwa 1 (Reiwa Gannen) corresponds to the year 2019.
Why do Showa 64, January 8 and Heisei 1, January 7 give an error?
Because those dates never existed. Emperor Showa died on January 7, 1989, ending the Showa era that same day. The new era, Heisei, took effect starting the following day, January 8. So Showa 64 only ever had a January 7, and Heisei 1 only starts from January 8.
Does this cover eras before Meiji, like Keio?
No. This tool only covers the five modern eras from Meiji onward, starting January 25, 1868.
How is the age calculated?
Today's year minus the birth year, minus one more if this year's birthday hasn't happened yet. For people born on February 29, non-leap years use February 28 as the effective birthday.
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