Japanese Age Calculator
Japan's legal age is 満年齢 (man-nenrei), which rises on each birthday like international age. The traditional 数え年 (kazoe-doshi) starts at 1 at birth and adds a year every January 1; it is still used for some customs. The page also shows the Japanese era year of birth.
Before you start
Method : Completed years, calendar-year count, and Gregorian era start dates.
Checked : Every era start (Meiji 23 Oct 1868, Taishō 30 Jul 1912, Shōwa 25 Dec 1926, Heisei 8 Jan 1989, Reiwa 1 May 2019) tested on the day before and the day itself. Birth dates 1900 or later. Man-nenrei is the legal age; kazoe-doshi is cultural only.
Review : not independently reviewed by an expert or by the organisation whose rules are used.
Your entries stay in this browser tab; nothing is sent or stored.
How to Use This Calculator
- Enter the birth date.
- Change the "calculate on" date if needed.
- Press Calculate.
Methodology & assumptions
- Man-nenrei: completed years (Feb 29 birthdays count on Feb 28 in common years).
- Kazoe-doshi: calculate-on year − birth year + 1.
Era start dates used: Reiwa May 1, 2019; Heisei January 8, 1989; Shōwa December 25, 1926; Taishō July 30, 1912; Meiji October 23, 1868. Japan adopted the Gregorian calendar in 1873, so Meiji-era dates before then are shown in today's calendar, not the old lunisolar one.
Worked examples
Born April 30, 2019: era year Heisei 31. Born a day later: Reiwa 1 (gannen).
Born June 15, 1990, on October 5, 2026: man-nenrei 36, kazoe-doshi 37, era Heisei 2.
Understanding your result
Use man-nenrei for documents. The earlier version gave Meiji as starting September 8, 1868 (the old-calendar date); it now uses the Gregorian equivalent.
Sources & further reading
- Wikipedia. Japanese era name (list of eras with Gregorian start dates).Secondary source used to cross-check era start dates.
Frequently Asked Questions
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