BaZi

What is The Four Pillars (Si Zhu)?

The Four Pillars (Si Zhu) are the year, month, day and hour pillars of a BaZi chart; each pillar pairs one Heavenly Stem with one Earthly Branch, giving eight characters in total, which is why the system is also called BaZi (the Eight Characters).

Also known as: Four Pillars of Destiny · Year Pillar · Month Pillar · Day Pillar · Hour Pillar · Si Zhu · Sizhu · BaZi Four Pillars

What Are the Four Pillars?

The "Four Pillars" (Si Zhu) are the most basic framework in BaZi astrology. The system takes the year, month, day and hour of a person's birth and converts each into a pair of stem-and-branch characters, forming four "pillars": the year pillar, month pillar, day pillar and hour pillar. Each pillar is made up of one "Heavenly Stem" and one "Earthly Branch," so the four pillars together add up to exactly eight characters. This is why BaZi (literally "Eight Characters") is also known as the Four Pillars. In Korea, the same reckoning of year, month, day and hour is known as Saju.

What Aspects of Life Does Each Pillar Represent?

Traditionally, the four pillars are said to correspond to different stages of life and different relationships. The associations below are a common starting point for learning to read a chart:

Year Pillar: often represents ancestors, family roots and childhood, and reflects the backdrop that one's upbringing provides.
Month Pillar: frequently linked to parents, siblings, career environment and young adulthood; an important position for observing character and one's stage of development.
Day Pillar: represents the self, with the Earthly Branch also commonly read for one's spouse and marriage. It is the center of the chart.
Hour Pillar: usually associated with children, later life and inner aspirations, reflecting a person's hopes and direction for the future.

Why Is the Heavenly Stem of the Day Pillar the Most Important?

Among the four pillars, the Heavenly Stem of the day pillar is called the "Day Stem" or "Day Master," and it represents the person themselves. Once the chart is drawn, virtually every relationship in the reading (such as the Ten Gods and the relative strength of the Five Elements) is calculated in reference to the Day Master, which is why it can be considered the heart of the entire chart. Understanding the Day Master is, in effect, finding the starting point for reading a BaZi chart.

How to Approach the Four Pillars

The Four Pillars offer a framework for understanding your innate tendencies and the rhythm of your life, rather than a fixed verdict on your fate. They can help reveal your natural inclinations, suitable directions for growth, and the themes at play in your relationships. It is best approached with an open and gentle mindset: treat the chart as a tool for self-understanding, and then, combined with your own effort, make the choices that suit you best.

Frequently asked questions

Q: Are the Four Pillars and BaZi the same thing?

Yes, they refer to the same thing. The Four Pillars are the year, month, day and hour pillars, each holding one Heavenly Stem and one Earthly Branch. Together they make eight characters, which is why the system is called BaZi (the Eight Characters).

Q: Which of the Four Pillars is the most important?

The day pillar is usually considered the most crucial, especially its Heavenly Stem, known as the Day Stem or Day Master. It represents the person themselves and serves as the reference point for calculating all the relationships across the chart.

Q: How is Korean Saju different from the Four Pillars?

Saju is simply the Korean name for the Four Pillars. It uses the same year-month-day-hour stem-and-branch system, and its core ideas align with the BaZi astrology commonly practiced in Taiwan. The differences lie mainly in terminology and the conventions of particular schools.

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Related terms

BaZi (Four Pillars of Destiny)

BaZi is a traditional Chinese method that converts a person's birth year, month, day, and hour into four pairs of stem-and-branch characters (the Four Pillars) — eight characters in total — used to explore personality and life patterns.

Day Master (Ri Gan)

The Day Master is the Heavenly Stem of the day you were born. In BaZi it represents you, the chart's owner, and serves as the central reference point for analyzing elemental strength and the Ten Gods.

Heavenly Stems & Earthly Branches (Tian Gan Di Zhi)

The Heavenly Stems and Earthly Branches are the timekeeping symbols of the Chinese calendar — ten stems and twelve branches that pair up into a sixty-unit cycle, and also the basic elements of the BaZi Four Pillars.

Korean Four Pillars (Saju)

Korean Four Pillars (Saju) is the Korean version of BaZi. It uses the same birth year, month, day and hour to set up the Four Pillars, but its reading style is more modern, with greater emphasis on Five-Element balance and the character of the Day Master.