Age, School Grade and Yakudoshi Calculator
Calculate age, Japanese school grade, yakudoshi and longevity milestones.
Common values
About this tool
Calculate exact age, days until the next birthday, Japanese school grade, traditional yakudoshi years, and the next Japanese longevity milestone from a birth date and reference date.
Age increases on each birthday. The reference date can be changed to calculate age at another point in time.
Japanese school cohorts run from April 2 through April 1 of the following year. Individual enrollment changes are not included.
Yakudoshi uses traditional counted age and varies by custom. This tool uses commonly listed principal ages and the adjacent years.
FAQ
- How is exact age calculated?
- The calculator subtracts birth year from reference year, then subtracts one if the birthday has not occurred yet. Change the reference date to calculate age at another point in time.
- Which school cohort includes an April 1 birthday?
- Japanese school cohorts run from April 2 through April 1 of the following year. An April 1 birth therefore belongs to the cohort one grade above an April 2 birth in the same calendar year.
- Does yakudoshi use exact age or counted age?
- This calculator uses traditional counted age for yakudoshi. A person is counted as age one in the birth year and gains one each New Year, so it can differ from exact age.
- How is a February 29 birthday handled?
- In a non-leap year, February 28 is used when calculating days until the next birthday. Exact age is still determined by comparing the entered birth and reference dates.
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