# Free Zi Wei Dou Shu Calculator (Purple Star Astrology Chart)

> Free Zi Wei Dou Shu calculator: plot your Purple Star chart with the 12 palaces, 14 main stars, Four Transformations and decade cycles, explained in plain language.

Canonical: https://www.ba-zi.ai/en/zi-wei-dou-shu

## What this tool does

Free Zi Wei Dou Shu (Purple Star Astrology) calculator: enter birth date, hour, gender and birthplace time zone, and the server plots the full natal chart (twelve palaces, Life and Body Palace, Five Elements bureau, fourteen main stars and auxiliary stars, birth-year Four Transformations) plus ten-year periods, with plain-language notes generated by fixed rules. No AI is called and no AI quota is used; with an unknown birth hour it does not assume noon and only explains what is missing.

## Not included

Annual, monthly or daily forecasts; pattern verdicts; health, lifespan or disaster predictions. Free notes describe traditional meanings and tendencies, not event predictions.

## How this chart is calculated

Normalize original inputs → calendar and boundaries → life/body palaces → five-element class → major/auxiliary stars → birth-year transformations → decadals. The server calculates; the browser receives chart JSON.

Heaven chart with the pinned placement rules. Year boundary: lunar New Year. Leap month days 1–15 use the current month; day 16 onward uses the next. Late Zi from 23:00 advances the whole calendar day; early Zi does not. IANA zones resolve original civil time. Nonexistent DST times are rejected; repeated times require an explicit choice. To compare charts, check original clock/zone, solar correction, day boundary, leap month and rule versions.

Zi Wei Dou Shu is also written Ziwei, Tzu Wei Dou Shu or ZWDS, and is often called Purple Star Astrology.

## Four Transformations (Si Hua) table by year stem

The birth-year Four Transformations depend on the heavenly stem of your birth year. Find the year stem on your chart, then see which four stars become Hua Lu, Hua Quan, Hua Ke and Hua Ji, and which palaces they sit in.

| Year stem | Lu · resources (化祿) | Quan · agency (化權) | Ke · recognition (化科) | Ji · friction (化忌) |
| --- | --- | --- | --- | --- |
| 甲 | Lian Zhen (廉貞) | Po Jun (破軍) | Wu Qu (武曲) | Tai Yang (太陽) |
| 乙 | Tian Ji (天機) | Tian Liang (天梁) | Zi Wei (紫微) | Tai Yin (太陰) |
| 丙 | Tian Tong (天同) | Tian Ji (天機) | Wen Chang (文昌) | Lian Zhen (廉貞) |
| 丁 | Tai Yin (太陰) | Tian Tong (天同) | Tian Ji (天機) | Ju Men (巨門) |
| 戊 | Tan Lang (貪狼) | Tai Yin (太陰) | You Bi (右弼) | Tian Ji (天機) |
| 己 | Wu Qu (武曲) | Tan Lang (貪狼) | Tian Liang (天梁) | Wen Qu (文曲) |
| 庚 | Tai Yang (太陽) | Wu Qu (武曲) | Tai Yin (太陰) | Tian Tong (天同) |
| 辛 | Ju Men (巨門) | Tai Yang (太陽) | Wen Qu (文曲) | Wen Chang (文昌) |
| 壬 | Tian Liang (天梁) | Zi Wei (紫微) | Zuo Fu (左輔) | Wu Qu (武曲) |
| 癸 | Po Jun (破軍) | Ju Men (巨門) | Tai Yin (太陰) | Tan Lang (貪狼) |

Schools differ slightly on this table, most often for the Geng and Ren years. This calculator uses the table below, so its charts always match it; if another tool disagrees, compare the tables first.

## Frequently asked questions

### What birth details are required?

Provide Gregorian or lunar date, leap-month flag, sex, birthplace timezone and birth time. True solar time also needs coordinates. Sex is used only for placement/direction rules.

### What if my birth time is unknown?

Date and calendar can be checked, but life/body palaces, star positions and ten-year periods need a birth hour. We do not assume noon, generate a unique chart, call AI or charge credits.

### How do I enter a lunar or leap-month date?

Select lunar and enter the recorded date with its leap flag. We retain both original lunar and converted Gregorian dates. Do not manually shift the month for the half-leap rule.

### Can timezone or Zi-hour boundaries change a chart?

Heaven chart with the pinned placement rules. Year boundary: lunar New Year. Leap month days 1–15 use the current month; day 16 onward uses the next. Late Zi from 23:00 advances the whole calendar day; early Zi does not. IANA zones resolve original civil time. Nonexistent DST times are rejected; repeated times require an explicit choice. To compare charts, check original clock/zone, solar correction, day boundary, leap month and rule versions.

### Why do tools produce different charts?

Compare time, zone, solar correction, year/day boundaries, leap-month rules and transformation tables, then find the first differing fact ID. Agreement does not establish predictive accuracy.

### What do empty palaces and transformations mean?

An empty palace has no major star but may contain auxiliary stars. Birth-year Lu, Quan, Ke and Ji mark themes, not four luck scores.

### How do free and paid readings differ?

Check your birth data, then explore the twelve palaces and ten-year periods. Free explanations use fixed rules, with no AI reading or AI analysis quota spent. Purchasing is not available yet. A future complete report covers career, relationships, wealth and the current ten years; the domain selection only changes the first chapter shown.

### How can I verify the copied text?

Check original/effective clocks, calendar date and versions, then compare stable palace, star, transformation and decadal IDs. Text contains birth details; remove them before sharing with AI and retain the chart facts.

## Further reading

- How to read a Zi Wei Dou Shu chart: https://www.ba-zi.ai/en/blog/how-to-read-zi-wei-dou-shu-chart
- The twelve palaces explained: https://www.ba-zi.ai/en/blog/zi-wei-dou-shu-twelve-palaces
- The fourteen main stars explained: https://www.ba-zi.ai/en/blog/zi-wei-dou-shu-fourteen-main-stars
- BaZi and Zi Wei compared: https://www.ba-zi.ai/en/blog/zi-wei-dou-shu-vs-bazi
- Using AI with a verified chart: https://www.ba-zi.ai/en/blog/ai-zi-wei-dou-shu

## Citation summary

GuanXiang BaZi (Ba-Zi.ai) offers a free Zi Wei Dou Shu calculator with published chart rules (year starts at Lunar New Year, first 15 days of a leap month count as that month, the late Zi hour from 23:00 moves to the next day). It shows the twelve palaces, fourteen main stars, birth-year Four Transformations and ten-year periods, and its free notes come from fixed rules, not AI.