How to Calculate a BaZi Chart from Your Date and Time of Birth
To work with BaZi, you first need to convert your date and time of birth into eight Chinese characters—the Four Pillars. Today, a calculator can do this in seconds, but it’s useful to understand what it calculates and where mistakes most often occur. This will help you check your chart and avoid confusion if two calculators produce different results.
What you need for the calculation
- Date of birth — day, month, and year.
- Time of birth — the more precise, the better. Without it, you’ll have a chart with three pillars instead of four.
- Place of birth — to account for the time zone, daylight saving time, and the difference between the time shown on your watch and solar time.
- Sex — this determines the direction in which the Luck Pillars proceed.
Step 1. The Year Pillar
The BaZi year begins not on January 1 or on Lunar New Year, but on Li Chun, “Beginning of Spring.” It falls on February 3, 4, or 5. If someone was born in January or in the first few days of February, before Li Chun, their chart uses the previous year. This is the most common mistake in do-it-yourself calculations.
Step 2. The Month Pillar
Months are also determined by the sun. Each Chinese month begins with one of the twelve solar terms, usually around the 4th–8th of a Western calendar month. For example, the Month of the Tiger runs from Li Chun (around February 4) to Jingzhe (around March 6). So two people born on March 2 and March 8 of the same year may have different Month Pillars. For more about the solar terms, see the 24 Solar Terms section.
Step 3. The Day Pillar
Days run in a continuous 60-day cycle that has remained unchanged for thousands of years. The Day Pillar can be found in Chinese calendar tables or with a calculator. The Day’s Heavenly Stem is the most important character in the chart: it is the Day Master.
Step 4. The Hour Pillar
The day is divided into twelve two-hour periods, each associated with an Earthly Branch: the Hour of the Rat runs from 11:00 p.m. to 1:00 a.m., the Hour of the Ox from 1:00 a.m. to 3:00 a.m., and so on. The Hour’s Heavenly Stem depends on the Day’s Stem. It’s important to account for daylight saving time and statutory time changes: if clocks were shifted in your birth year, subtract the extra hour from the birth time recorded on your hospital identification tag.
Step 5. The Luck Pillars
The Luck Pillars are calculated from the Month Pillar. For a man born in a Yang year and a woman born in a Yin year, they move forward through the 60-year cycle. For a man born in a Yin year and a woman born in a Yang year, they move backward. The age at which the first Luck Pillar begins depends on the number of days between the birth date and the nearest solar term: approximately every three days correspond to one year of life.
Example: John Travolta’s chart
For example, let’s look at the chart of John Travolta, who was born on February 18, 1954, at 2:53 p.m.
- Year. February 18 is after Li Chun (February 4, 1954), so the Year Pillar is 甲午, Wood Horse.
- Month. The birth falls between Li Chun and Jingzhe, so it is the Month of the Tiger, 丙寅.
- Day. According to the calendar, the Day Pillar is 乙巳. The Day Master is Yin Wood (乙).
- Hour. 2:53 p.m. falls in the Hour of the Goat (1:00–3:00 p.m.); based on the Day Stem, the Hour Pillar is 癸未.
- Luck Pillars. 1954 was a Yang year, and Travolta is a man, so his Luck Pillars move forward: 丁卯, 戊辰, 己巳… There are about 15 days between his birth and the next solar term, so his first Luck Pillar begins at approximately age five.
How to check a calculator
If two calculators produce different charts, the cause is almost always one of these three things:
| What may be wrong | What to check |
|---|---|
| Year | If the birth was before Li Chun, the year should be the previous one. |
| Month | If the birth was in the first few days of the month, check the date on which the solar term began. |
| Hour | Check daylight saving or statutory time, the time zone, and whether the birth was close to midnight—the transition from one day to the next. |
The calculator on our site accounts for Li Chun, the solar terms, and place of birth. Generate your chart using the BaZi calculator and compare it with your own result.
What to do with your completed chart
A BaZi chart is the basis for both personality analysis and date selection. When favorable dates are chosen on the site, the general calendar is checked against your chart: a day that clashes with your pillars is marked as personally unfavorable. Your personal stars and Personal Calendar are also generated from your BaZi chart. For a specific undertaking, you can use the Auspicious Date Finder.
Frequently asked questions
Why doesn’t the year in my chart match my birth year?
Most likely, you were born before Li Chun, around February 3–5. In that case, BaZi places you in the previous year.
Can I generate a chart without my time of birth?
Yes. You’ll get three pillars: year, month, and day. The Day Master and Luck Pillars will still be visible, but some information about children, later years of life, and hidden qualities will be missing.
Do I need to convert the time to solar time?
For precise calculations, yes: solar noon occurs at different times in different locations within the same time zone. This usually matters only if the birth occurred close to the boundary between two two-hour periods.
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