Age Calculator

1. Enter the date of birth.
2. The age today, in exact years and in kazoedoshi, appears straight away.
3. To get the age on another day, enter a target date.
4. The age on that past or future date appears straight away.
5. If the date of birth is on a Japanese era calendar, choose the era and type the era year.

Exact age is the age you would give if someone asked you today. You are 0 in the year you are born, and you gain a year on each birthday. This is the age used on official forms in Japan and in most countries.

• On or after the birthday: exact age = current year − year of birth
• Before the birthday: exact age = current year − year of birth − 1

Kazoedoshi is the traditional Japanese way of counting age. You are 1 in the year you are born, and everyone gains a year together on 1 January rather than on their own birthday. It still turns up at shrines and temples, and for celebrations such as yakudoshi and kanreki.

• kazoedoshi = current year − year of birth + 1
• On or after the birthday: kazoedoshi = exact age + 1
• Before the birthday: kazoedoshi = exact age + 2

Japanese dates are often written with an era name and a year counted from the start of that era. You can type a date of birth either way here — pick an era and the year box switches to that era's year, and the chart below shows the era for every birth year.

• Reiwa — from 1 May 2019
• Heisei — 8 January 1989 to 30 April 2019
• Showa — 25 December 1926 to 7 January 1989
• Taisho — 30 July 1912 to 24 December 1926
• Meiji — 23 October 1868 to 29 July 1912

The first year of an era is written "gannen" (year 1), and an era's first and last years are shared with the era next to them, so a date right on the boundary can be written either way.

This tool is available for free.