What is Bazi? Eight characters and four pillars

From the HUANGJUI Design archive

The system

What are the eight characters and four pillars?

The archive presents Bazi as a Chinese-calendar-based method used when planning ventures. Birth date and time pair heavenly stems with earthly branches to identify a person’s elements. Within the belief, these are considered when choosing supporting elements and directions associated with wisdom, progress, health and fortune.

Chinese Bazi: the four pillars

The system uses a solar calendar, five elements, yin and yang, and 60 combinations of heavenly stems and earthly branches. These combinations represent year, month, day and hour in an eight-character chart, alongside fortune periods, annual and monthly cycles.

The solar calendar

The archive describes a solar year of about 365.25 days or 12 months and relates seasonal changes to Earth’s orbit and axial tilt, stated as 23.4443291 degrees. Four seasons each cover three months, with two solar terms per month to guide agriculture and daily life.

Weather changes with each season

In the described cycle, a season starts with active yang energy, reaches its central yin element in the middle month and stores energy in earth in the final month before the next season.

Spring

Wood, east: February is Yin wood, March Mao wood and April Chen earth in the seasonal branch sequence.

Summer

Fire, south: May is Si fire, June Wu fire and July Wei earth.

Autumn

Metal, west: August is Shen metal, September You metal and October Xu earth.

Winter

Water, north: November is Hai water, December Zi water and January Chou earth, closing the seasonal year.

Components of the chart

The year pillar

Chinese astrology uses the sexagenary cycle for charts and interpretation: Jia-Zi corresponds to Rat, followed by Yi-Chou for Ox, continuing through 60 pairs over 60 years before restarting.

The archive also describes life or fortune periods through the same recurring stem–branch framework, illustrating it with Jia-Zi, Yi-Chou and the 60-year cycle.

The month pillar

Month and fortune-period stems are calculated from the year pillar, with major solar-term changes marking months. The year has 24 solar terms reflecting seasonal weather associated with Earth’s orbit. A five-day interval is called a hou.

One hou is five days; three hou make one solar term.

The archive groups a major and minor solar term into a solar month. It places major terms around the 3rd–9th and minor terms around the 20th–24th of a Gregorian month, referring to solar positions and about 15-degree intervals. A full 60-pair monthly cycle takes five years.

The day pillar

The day’s stem–branch pair is looked up in a long-range calendar, repeating every 60 days. The hour system divides 24 hours into twelve two-hour periods, described as six yang daytime and six yin nighttime periods. Zi runs from 23:00 to 00:59 and Hai from 21:00 to 22:59. Hour pairs complete a cycle in five days and their stems depend on the day stem. The archive also describes two-minute subsidiary intervals within each 120-minute period.

The lunar calendar

Lunar months have 30 or 29 days, so their transitions usually differ from solar-term changes. The archive describes a 354-day year, about eleven days shorter than the solar year, with an extra month roughly every three years. The year begins at Chinese New Year, the first day of the first lunar month. It connects lunar phases with weather and tides, describing fuller tides on the 3rd and 18th and lower tides on the 9th and 23rd.