Day and Time of Birth
"Bazi" means "8 characters."



The day and time of birth of a person is generally given not as a single numerical number, but as a combination of four components (pillars), namely: year, month, day, and hour.

For example, November 25,1985 at 2 pm

Each of the 4 components may be expressed by a 2-digit number. Year:  85
Month: 11
Date:  25
Hour:  14

Thus, the "birthday" is expresed by 8 "digits": 85 - 11 - 25 - 14


Year: 2-digit number ranging from 00 to 99.
Year number modulo 100, meaning omitting the century.
85 may mean 1985, 1885, 1795, etc.
Valid only for first century and forward

Month: 2-digit number ranging from 1 to 12

Day: 2-digit number ranging from 1 to 31

Hour: 2-digit number ranging from 0 to 23
Zero is mid-night.

The Chinese system uses exactly the same idea of four pillars (components): names, Year, Month, Day, and Hour.
Each pillars uses 2 zi (characters) instead of 2 digits.
Year: 2-character number ranging from 1 to 60. Month: 2-character number ranging from 1 to 12. There are generally 12 months in a year.
Day: 2-character number ranging from 1 to 30. The longest month has 30 days.
Hour: 2-character name ranging from 1 to 12. Each "double-hour interval" is two hours long. The first "hour" covers 11pm to 1 am. See Hour.html for more details.

The Julian date of November 11,1985 must be converted to its Chinese Lunar Calendar date. Using a calendar-conversion table(program), we find that November 11, 1985 is the 14-th Day of the 10-th Month in the Chinese Year of 08 (Yi Chou) The time of 2pm is the 8-th "double hour."

Thus the Year-month-day-hour is: 02 - 10 - 14 - 08.

These four components of one's birth date are not yet the Ba Zi (8 charaters) to be used in Chinese astrology, fengshui, horoscope, etc.
One need to go throught a rather convoluted procedure to convert each of the 4 components into 4 pillars. Each pillar consists of 2 characters, making a total of 8 characters.

The final result is: Yi Chou - Ding Hai - Wu Wu - Ji Wei