How Is a BaZi Chart Calculated? What Birth Information Do I Need to Provide?
已更新：9月17日
To prepare a BaZi chart, Gé Rén needs only three pieces of information: your date of birth, time of birth, and gender. Gé Rén uses the established rules of the traditional Chinese perpetual calendar and the Heavenly Stems and Earthly Branches calendar system to derive the Four Pillars and eight characters. The process follows defined calendrical and calculation principles. It is not based on guesswork.
Your date of birth may be provided according to either the Gregorian calendar or the Chinese lunar calendar. The calendar you use is less important than the accuracy of the date you provide.
Your birth time should be the local clock time recorded at your place of birth. Gender is also required because it affects how relationships within the chart are interpreted and how the Major Luck Cycles are arranged. Together, these three pieces of information provide Gé Rén with the essential foundation for preparing your chart and carrying out the subsequent analysis.
Your birth year, month, day, and time form the Year Pillar, Month Pillar, Day Pillar, and Hour Pillar respectively. If the Four Pillars are new to you, you may first read Gé Rén’s earlier article, What Is BaZi? A Simple Introduction to the Four Pillars of Destiny, for an introduction to the basic structure of a BaZi chart.
One point often surprises people who are new to BaZi: the month in a BaZi chart is determined neither by the Gregorian calendar month nor by the Chinese lunar calendar month. It is defined by the seasonal divisions within the Twenty-Four Solar Terms. The Month Pillar does not change automatically on the first day of a Gregorian month or the first day of a lunar month. Instead, it is determined by the seasonal division that applies at the precise moment of birth.
Your birth time determines the Hour Pillar. Traditionally, a day is divided into twelve periods, with each period lasting two hours. Each period has a clearly defined starting and ending time. If a person is born close to the boundary between two periods, a difference of even one minute may place the birth in a different period and produce a different Hour Pillar. For this reason, the minutes are just as important as the hour when providing a birth time.
The Year, Month, Day, and Hour Pillars are derived according to established calendrical rules. Gé Rén asks for accurate information from the outset because a correctly prepared chart is the foundation of the analysis that follows.
Frequently Asked Questions
What if I do not know my time of birth?
If you do not know your exact birth time, you may still begin by explaining the situation to Gé Rén.
Depending on the information available, Gé Rén may compare the chart owner’s background, character traits, significant life events, and patterns of development during different stages of life. This can help identify which possible birth periods produce charts that most closely correspond with the person’s actual circumstances and may allow the probable range of birth times to be narrowed.
This process is more involved than a standard BaZi analysis and requires the chart owner to provide sufficient and reliable information. Whether the possibilities can be narrowed to one likely birth period depends on the completeness of the available information and whether the resulting charts show sufficiently clear differences. It is therefore not possible to guarantee that the original birth time can be established in every case.
If you do not know your birth time, simply let Gé Rén know. Gé Rén will first review the information you already have and then explain the available options and the appropriate next steps.
What Are the Twenty-Four Solar Terms, and How Does BaZi Use Them?
The Twenty-Four Solar Terms (二十四節氣) form a traditional Chinese calendrical system that reflects seasonal changes throughout the year. The system divides the year into twenty-four points according to the Sun’s annual movement.
The Twenty-Four Solar Terms alternate between twelve Month-Opening Terms (節) and twelve Midpoint Terms (氣). Each Month-Opening Term marks the beginning of a new solar month. A Midpoint Term falls around the middle of that month and is therefore also known by its full name, Mid-Season Point (中氣). It does not independently begin or end a Month Pillar.
A BaZi month is therefore determined neither by the Gregorian calendar month nor by the Chinese lunar calendar month. The Month Pillar does not change automatically on the first day of a Gregorian month or the first day of a lunar month. What matters is whether the precise moment of birth falls before or after the relevant Month-Opening Term.
This is why two people born in the same Gregorian month, on the same day, and even within the same two-hour period may still have different Month Pillars. If the relevant Month-Opening Term occurs within that period, with one person born before the transition and the other born after it, the two births fall into different BaZi months.
Why Does Gé Rén Need to Know My Gender?
Even when two people are born on exactly the same date and at exactly the same time, giving them the same eight characters, gender still affects the analysis in three ways.
First, gender helps define the human relationships represented within the chart. For example, for a female chart owner with a Fire Day Master, Water represents the husband. For a male chart owner with a Fire Day Master, Water represents the children. Gender therefore helps place the people represented in the chart within the correct relationships.
Second, gender affects the direction in which the Major Luck Cycles are arranged. Whether the cycles proceed forwards or backwards is determined by gender together with whether the birth year is yin or yang. Different directions produce different sequences of the Five Elements.
Third, gender affects the age at which the first Major Luck Cycle begins. Even when the eight characters are identical, the first Major Luck Cycle may begin at very different ages for male and female chart owners.
Because the Major Luck Cycles have a profound influence on the chart, gender is not an insignificant piece of information.
Would You Like to Know More?
If this article has made you more curious about how a BaZi chart is calculated, here are two topics you may wish to explore further:
If daylight saving time was in effect at the place of birth, how should the birth time be handled when preparing a BaZi chart?
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Why can two people born within the same two-hour period still have different Year or Month Pillars?
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Which topic would you most like to explore first? You are also welcome to suggest a question of your own.
If you would like to learn more about one of the topics above, first copy the topic, then select “Suggest a Topic to Gé Rén” below. On the dedicated page, open the prepared email and paste the topic after the colon in the subject line. If you have another question, you may enter it directly in the email message.
The questions readers submit, together with the level of interest shown in each topic, will serve as important references when Gé Rén plans future articles.