How it is calculated
Full age = this year − birth year (−1 if your birthday has not come yet) Traditional age (kazoedoshi) = this year − birth year + 1 Era year = Western year − (year before the era’s first year); year 1 is called “gannen” Zodiac: heavenly stem = (birth year − 4) mod 10, earthly branch = (birth year − 4) mod 12 Elementary school entry = April of the year you turn 6 if born by April 1; otherwise the following April
- Legal age: Under the Act on Calculation of Age, you become a year older at the end of the day before your birthday. That is why children born on April 1 join the earlier school year.
- Pension and care “day reached”: The day you “reach 65” is the day before your birthday. For people born on the 1st, that day falls in the previous month, so eligibility starts a month earlier.
- Kazoedoshi: You are 1 at birth and add a year every New Year. Today it is mostly used for unlucky years (yakudoshi) and longevity celebrations.
Japanese era start dates
| Era | Start date | Subtract from Western year |
|---|---|---|
| 明治 | October 23, 1868 | 1867 |
| 大正 | July 30, 1912 | 1911 |
| 昭和 | December 25, 1926 | 1925 |
| 平成 | January 8, 1989 | 1988 |
| 令和 | May 1, 2019 | 2018 |
For example, 1990 − 1988 = Heisei 2 and 2026 − 2018 = Reiwa 8. Up to January 7, 1989 it was Showa 64.
Example: born April 15, 1990 (as of October 21, 2026)
| Item | Result |
|---|---|
| Full age / kazoedoshi | 36 / 37 |
| Japanese era | Heisei 2 |
| Zodiac | Kanoe-uma (庚午) · Horse |
| Elementary school entry | April 1997 |
| Long-term care Category 2 (day reaching 40) | April 14, 2030 |
| Standard old-age pension (day reaching 65) | April 14, 2055 |
| Late-stage elderly medical care (75th birthday) | April 15, 2065 |
176 days to the next birthday.
Age milestones and caveats
- 18: Adulthood since April 2022: you can sign contracts without parental consent, but drinking, smoking and betting on public races start at 20.
- 20: National Pension membership becomes mandatory (from the day before your birthday; students can apply for a payment deferral).
- 40: You become a Category 2 long-term care insured person and a care premium is added to health insurance.
- 60, 65 and 75: The old-age pension normally starts at 65; claiming early from 60 reduces it by 0.4% a month (0.5% if born on or before April 1, 1962), and deferring up to 75 increases it by 0.7% a month. From your 75th birthday you move to the late-stage elderly medical care system.
- The zodiac uses years starting on January 1. Results for January–February births can differ from the traditional risshun (early February) boundary.
- School grades assume a 6-3-3 path with no repeated or skipped years. Pension claim timing depends on your situation — check with the Japan Pension Service.
Frequently asked questions
Why are children born on April 1 in the earlier grade?
Legally they turn 6 at the end of March 31, so they are already 6 before the school year starting on April 1.
What is the zodiac for 2026?
Hinoe-uma (丙午), which returns every 60 years; 1966 was also hinoe-uma.
What does “man-nenrei” on Japanese forms mean?
It means full age. Japan uses full age in daily life as well.