Calculate age
Enter a birth date and an as-of date to see man-nenrei, kazoedoshi, wareki, eto, yakudoshi, and the next birthday. You can type Gregorian or Japanese era dates.
Date of birth
Gregorian
Japanese era
Year
Month
Day
As-of date
Year
Month
Day
Sex (for yakudoshi)
Male
Female
Results
Legal age (man-nenrei)
36years 4months 28days
Kazoedoshi
37years
Date of birth (wareki)
平成2年4月2日
Eto (birth year)
庚午（午）
Yakudoshi
None（Kazoedoshi37years）
Next birthday
2 April 2027 (215 days)
Date the age is reached
37 years: 1 April 2027 (the day before the birthday)
How man-nenrei is counted
Man-nenrei starts at birth and increases on the day before the birthday. This tool also splits that age into years, months, and days.
For 29 February births, non-leap years use 28 February as the cutoff — common in administration and insurance.
Kazoedoshi and yakudoshi
Kazoedoshi starts at 1 in the birth year and increases every New Year. Shrine yakudoshi (mae / hon / ato) is usually based on kazoedoshi.
Typical hon-yaku ages: men 25, 42, 61; women 19, 33, 37, 61 (all kazoedoshi). Taiyaku is often 42 for men and 33 for women. This is custom, not statute, and varies by region and sect.
Wareki, eto, and the age chart
We also show the birth year’s wareki label and eto. In a year with an era change, the wareki converter shows the dual notation.
For many birth years at a glance, use the age chart. For one person’s exact man-nenrei or yakudoshi, use this calculator.
Frequently asked questions
Should I use man-nenrei or kazoedoshi?
Administration, insurance, and “how old are you?” usually mean man-nenrei. Yakudoshi and some customs use kazoedoshi. Switch to match the purpose.
Does yakudoshi always “hit”?
No. Yakudoshi is a shrine and regional custom, not legal age. The display is for reference.
Can I enter a wareki birth date?
Yes. Switch to wareki and enter era, year, month, and day. In an era-change year, also check the wareki converter.
Are my inputs sent to a server?
No. The calculation stays on your device. We do not send birth dates in order to calculate.