You must know how to count your age. And that might be only one. But there are some other ways to count age for human. In this app I implement few of them.


We usually use this counting way. This is generally usage in worldwide. Newborns start at age 0. And once at every birthday, one year is added to the person's age.

Nothing special. Nothing else. Isn't it?

When does the age change? The birthday? What if your birthday is February 29 of a leap year. Is it February 28 ? Or is it March 1 once every 4 years?  I don't know other countries besides Japan. But in Japan we have a law for age counting. It says that the age should be added at the end of the day before birthday.

If your birthday is February 29, the moment is the end of Februrary 28. So it is added at the moment of the end of February 28 even if it is a leap year or not. 


East Asian age reckoning (Counting age)

In east asia like Japan, China, Korea and Vietnam, we used to use this type of way to count age. In modern times, we do not officially use this method, but they are sometimes used in private situations. Korean use it more often than the others.

Newborns start at the age of one year, and at the New Year's Day one year is added to the person's age. People may be one or two years older in East Asian reckoning than in the modern age system.

In China, the age changes on the lichun. In Japan, Vietnam, and South Korea, New Year's Day as the date for change of age is used. Depending on the region, they might use Setsubun as that day. or  New Year's Day of the traditional lunisolar calendar.

See details in Wikipedia.

Japanese Women

Singer-songwriter TOKORO George sings in "Hong Kong & Tokyo";

It takes 30 years in Hong Kong to make a woman 30 years old.
It takes 50 years in Tokyo to make a woman 30 years old.

As symbolized by this song, Japanese women slowly take ages. Details of how to count with this lyric are not clear and can not be implemented. I only  implemented some of the age calculation methods whose details have been clarified.

- TANIYAMA Hiroko ... Singer-songwriter. "I turn back my age from the age of 23 and make it increase again when I turn 18".

- INOUE Kikuko ... Voice actress and Singer. "Eternal Seventeen".