Enter a date of birth to instantly calculate the age. It shows the standard full age (years completed), plus a precise years/months/days breakdown, total days lived, the day of the week you were born, and days until the next birthday. The reference date defaults to today but can be set to any date, so you can also find how old someone was — or will be — on a given day. It also shows the Japanese kazoedoshi: a traditional count where you are 1 at birth and gain a year every New Year's Day (used for shichi-go-san, unlucky-age years and longevity celebrations). Everything runs in your browser; the date of birth you enter is never stored or uploaded.
How to use
- Enter the date of birth.
- Leave the reference date on today, or change it to the date you want.
- Read the full age and kazoedoshi, plus the breakdown, days lived, weekday and days to the next birthday.
FAQ
What is the difference between full age and kazoedoshi?
Full age counts from 0 at birth and adds a year on each birthday — the everyday way age is given. Kazoedoshi is a traditional Japanese count: you are 1 at birth and gain a year on each New Year's Day (Jan 1). It is used for events such as shichi-go-san, unlucky-age (yakudoshi) years and longevity celebrations.
Can I calculate the age on a past or future date?
Yes. Change the reference date to find how old someone was — or will be — on a specific day. It defaults to today.
Does it handle leap-year births (Feb 29)?
Yes. The breakdown and day counts follow the calendar. For the next birthday in a year without Feb 29, it follows your environment's date handling, so treat that figure as a guide.
Is the date of birth I enter stored?
No. All calculation runs in your browser; the date of birth is never stored or uploaded and is not sent to any server.