Comparison · 紫微斗數 與 八字
Zi Wei Dou Shu vs BaZi
BaZi and Zi Wei Dou Shu are separate Chinese birth-chart systems that read the same birth moment in different ways. BaZi, the Four Pillars, writes the year, month, day, and hour as eight characters and reads them through the Five Elements, the Day Master, the Ten Gods, and luck cycles. Zi Wei Dou Shu places fourteen major stars across twelve life-domain palaces and reads them with the Four Transformations and timing layers. Neither is a simplified version of the other; they can be compared, and many readers use both.
- BaZi
- 八字, Four Pillars of Destiny; unit is the stem-branch pair; centre is the Day Master
- Zi Wei Dou Shu
- 紫微斗數, Purple Star Astrology; unit is the palace; centre is the Life Palace
- Same input
- Birth date and two-hour birth period; gender for cycle direction in both
- Different calendars
- BaZi turns the year at Li Chun and the month at solar terms; Zi Wei uses lunar months and days
- On kaucim.ai
- Both are cast from one form; the Zi Wei calculator includes a BaZi cross-check, the BaZi calculator leads with the pillars
Side by side
| Dimension | BaZi (Four Pillars) | Zi Wei Dou Shu |
|---|---|---|
| Chinese name | 八字 (eight characters), 四柱 (four pillars) | 紫微斗數 (Purple Star Astrology) |
| Basic unit | Four stem-branch pairs: year, month, day, hour | Twelve palaces, each holding stars |
| Calendar basis | Solar: year begins at Li Chun, months at the twelve major solar terms | Lunar: month and day from the lunar calendar, year from Lunar New Year |
| Central reference | The Day Master, the day stem | The Life Palace and its San Fang Si Zheng |
| Main vocabulary | Five Elements, Ten Gods, hidden stems, branch relationships | 14 major stars, brightness, Four Transformations |
| Number of moving parts | 8 visible characters plus hidden stems | 12 palaces, 14 major stars, dozens of auxiliaries |
| Ten-year timing | Luck pillars (大運) derived from the month pillar; start age from days to the nearest solar term | Decades (大限) that move one palace at a time; start age equals the bureau number |
| Reads best | Constitution, element balance, strength and weakness, overall timing | One life domain at a time: money, marriage, career, health |
| Learning curve | Compact structure, deep interpretation | Large structure, faster to see a domain |
| Hour handling | Two-hour branch; late Zi kept on the same date on kaucim.ai | Same two-hour branch; same late-Zi rule on kaucim.ai |
Same birth, two calendars
The difference that surprises people most is the year. BaZi turns the year pillar at Li Chun, the solar term around 4 February. Zi Wei Dou Shu, as implemented on kaucim.ai and in most software, turns the year at Lunar New Year. In 1995 Lunar New Year fell on 31 January and Li Chun on 4 February, so a person born on 2 February 1995 has a 乙亥 year in the Zi Wei chart and a 甲戌 year pillar in BaZi. Both are correct within their systems.
The month diverges more often. A BaZi month pillar changes at a solar term, which can fall on any day of a calendar month; a Zi Wei month is a lunar month. Two people born a week apart can share a BaZi month and sit in different Zi Wei months, or the reverse.
Worked example
Birth: 6 February 1995, 15:00 to 17:00 (Shen hour), male. BaZi writes it as 乙亥 year, 戊寅 month, 戊辰 day, 庚申 hour; the Day Master is 戊 Wu, Yang Earth, born in a 寅 (early spring, Wood) month that controls Earth. Zi Wei places the Life Palace at 午 with the Zi Wei star resident and Ke attached, the bureau is 木三局 (Wood, 3), and the Body Palace is the Career Palace.
A BaZi reader would start from the Earth Day Master under spring Wood and ask what supports it. A Zi Wei reader would start from Zi Wei in the Life Palace, look at Tan Lang opposite and at the Wealth and Career trine, and describe disposition by domain. The two readings are not translations of each other; they answer from different angles, which is the point of holding both.
Which to use, and which to learn first
- For a question about one domain (should I take this job, why does money not stay), Zi Wei gives a dedicated palace with named stars to read. Start there.
- For a question about constitution and timing (what kind of pressure suits me, which decade is the working decade), BaZi's Day Master and luck pillars are more direct.
- For learning, most beginners start with BaZi because eight characters and ten relationships are a small vocabulary. Zi Wei's twelve palaces then make sense faster.
- For a cross-check, cast both. When they agree, the statement is stronger; when they disagree, the disagreement is itself informative and worth reading rather than averaging away.
Common mistakes
- Calling one "more accurate". They model different things, and a claim of accuracy for either is a claim about the reader, not the system.
- Mixing vocabulary. "Spouse Palace" in BaZi usually means the day branch; in Zi Wei it is a palace with stars. "Life Palace" exists in both, and the BaZi one (八字命宮) is a different object from the Zi Wei one.
- Expecting the same year stem. Late-January and early-February births can carry different year stems in the two systems.
- Treating the Chinese zodiac as either. The zodiac animal is the year branch only; both systems use far more than that.
Questions people ask
Is BaZi or Zi Wei Dou Shu more accurate?
Neither. BaZi reads element balance and timing around the Day Master; Zi Wei reads stars by life domain. Casting both from the same birth and comparing is more informative than ranking them.
Can I use the same birth time for both?
Yes. Both resolve the birth to a two-hour branch. Check the same boundary questions once (daylight saving, longitude, late Zi) and both charts use the answer.
Why does my BaZi say one year and my Zi Wei chart another?
Because BaZi turns the year at Li Chun and Zi Wei turns it at Lunar New Year. Births in the days between the two dates carry different year stems in the two systems.
Does kaucim.ai use both?
Yes. The Zi Wei calculator casts the twelve-palace chart and cross-checks it with BaZi in the full reading; the BaZi calculator leads with the four pillars and adds the Zi Wei view.
Related concepts
Sources and calculation version
- Zi Wei calculation assumptions on kaucim.ai
- BaZi calculation rules on kaucim.ai · the rules table on the calculator page
- iztro documentation · Zi Wei engine
- lunar-typescript · BaZi engine; solar-term and Li Chun boundaries
Last checked against the chart engine on 2026-09-14.
Enter the birth once and see the twelve-palace chart with the BaZi pillars beside it.
Cast both charts from one form