Japanese Age Calculator & Quick-Reference Table (Kazoe-doshi, Wareki, Eto)
Enter a birth date or year to get the current age, traditional kazoe-doshi age, Japanese era birth year and zodiac animal, plus a 100-year age reference table.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
Kazoe-doshi: you are 1 at birth and gain a year every New Year (birth year − current year + 1... i.e. current year − birth year + 1).
Age quick-reference table (nenrei hayami-hyō)
The age column is the age reached on this year’s birthday — before the birthday it is one less.
| Year | Japanese era | Age this year | Eto |
|---|
Everything runs in your browser. Kazoe-doshi is the traditional Japanese count used for yakudoshi and ceremonies. Click a value to copy.
About this tool
This Japanese age calculator tells you, from a birth date or just a birth year, the current age (man-nenrei, the Western count), the traditional kazoedoshi count, the wareki era of the birth year and the zodiac animal — plus a 101-year quick-reference table with your row highlighted. Kazoedoshi, used for ceremonies like yakudoshi and some shrine rites, counts a person as 1 at birth and adds a year every New Year. Great for forms, celebrations such as shichi-go-san or kanreki, and family history. Everything is calculated in your browser.
Frequently asked questions
What is the difference between man-nenrei and kazoedoshi?
Man-nenrei is the familiar Western count: you are 0 at birth and gain a year on each birthday. Kazoedoshi is the traditional East Asian count: you are 1 at birth and everyone gains a year together on 1 January, regardless of birthday. So before your birthday each year, kazoedoshi is two ahead of man-nenrei; after it, one ahead. Official paperwork uses man-nenrei, while yakudoshi and some ceremonies still use kazoedoshi.
When do I use kazoedoshi today?
Mainly in traditional and religious contexts: yakudoshi (unlucky years) at shrines and temples, memorial services, and sometimes shichi-go-san or celebration ages like kanreki depend on region and family custom. Modern law, schools, hospitals and contracts all use man-nenrei. If a shrine asks your age for a rite, check whether they mean kazoedoshi — this tool shows both so you can answer either way.
Is my birth date kept private?
Yes. The age, era and zodiac calculations all run as JavaScript inside your browser, so the birth date you enter is never uploaded, stored or shared. A birth date is sensitive personal data, which is exactly why this tool was built to work fully locally — you can even use it offline once the page has loaded.
Why do people born in January–April end up a school year ahead in Japan?
Japan's school year starts in April, and a child enters primary school in the April after turning six. Because Japanese law treats a person as having aged on the day *before* their birthday, someone born on 1 April is legally six on 31 March — one day inside the earlier year — so they enter school a year ahead of a classmate born on 2 April. This is why 1 April, not 31 March, is the cut-off, and it is the single most misread date in the whole system.
How does this differ from the Korean way of counting age?
Korea long used a count where you are one at birth and gain a year every 1 January, which could make a December baby two years old after a few days. In June 2023 Korea standardised on international age (만 나이) for legal and administrative purposes, so the two systems now largely agree. Japan's kazoedoshi works the same way as the old Korean count — one at birth, +1 at New Year — but it survives only in ceremonies such as yakudoshi and shichi-go-san, never in official documents.