How to Cast a Zi Wei Dou Shu Chart: From Lunar Birthday to Fourteen Stars in Five Steps

Computers cast charts now, but knowing how a chart is built makes reading it much more solid: you will see why one hour’s difference moves the entire chart, and why people born in a leap month should double-check. Below we build our example chart (born 10 July 1990 at 12:00 noon, male) one step at a time.

Step 1: convert to the lunar calendar; handle leap months and the Zi hour

Zi Wei Dou Shu uses the lunar year, month and day and the two-hour period. 10 July 1990 is the 18th day of the leap fifth month of the Geng-Wu year, and 12 noon falls in the Wu hour.

This date happens to hit two common pitfalls:

• Leap month: it is in a leap fifth month. This site counts days 1–15 of a leap month as that month and days 16 onward as the next, so the 18th is treated as the sixth month. Some schools count the whole leap month as the month itself, which would move the Life Palace by one box.
• Start of the year: Zi Wei changes years at Chinese New Year, while BaZi uses Li Chun. This date is well past New Year, so the birth year is Geng-Wu.

Also, births after 11 pm count as the Zi hour of the next day on this site (the date moves forward one day). This is another common point of difference between schools.

Step 2: find the Life Palace and the Body Palace

The rule: start the first month at Yin and count forward to the birth month; from there, count the hours backwards from Zi to the birth hour to find the Life Palace, and forwards to find the Body Palace. From Yin, counting forward to the sixth month reaches Wei. Starting Zi hour at Wei and counting back to the Wu hour lands on Chou, so the Life Palace is in Chou. Counting forward from Wei to the Wu hour also lands on Chou: this chart has Body and Life together.

Step 3: give each palace a stem and find the bureau

The stems of the twelve palaces follow the “Five Tigers” rule, starting from the Yin palace: in Jia and Ji years Yin gets Bing, in Yi and Geng years Wu, in Bing and Xin years Geng, in Ding and Ren years Ren, in Wu and Gui years Jia. The example is a Geng year, so Yin is Wu-Yin; counting on, the Chou palace is Ji-Chou.

The na yin of the Life Palace’s Ji-Chou is Thunderbolt Fire, so the chart is a Fire-6 bureau. There are only five bureaus, and in our sample each accounts for about a fifth of charts (19.6–20.4%):

Step 4: place Zi Wei, and the other thirteen follow

Zi Wei’s position depends on the bureau and the lunar birthday. The method: add the smallest number to the birthday that makes it divisible by the bureau number; the quotient is how many boxes to count from Yin; if the number you added is odd, step back that many boxes, if even, step forward. The example was born on the 18th in a Fire-6 bureau; 18 divides by 6 exactly, giving 3 with nothing added, so counting three boxes from Yin puts Zi Wei in Chen.

Once Zi Wei is placed, the other thirteen major stars follow: one box back from Zi Wei is Tian Ji, skip one for Tai Yang, then Wu Qu and Tian Tong, then skip two for Lian Zhen. Tian Fu mirrors Zi Wei across the Yin–Shen axis and lands in Zi; from there Tai Yin, Tan Lang, Ju Men, Tian Xiang, Tian Liang and Qi Sha follow in order, and three boxes further is Po Jun. That is why all the major stars are tied together: shift the hour or the day a little, Zi Wei moves, and all fourteen stars move with it.

Here is the full table for placing Zi Wei. Find your bureau and lunar birthday to see which branch holds Zi Wei:

In our sample Zi Wei falls in Chen most often (11.3%) and in Zi least often (4.5%). That unevenness comes from the placement formula itself; it has nothing to do with one palace being nobler than another.

Step 5: minor stars, transformations and decades

After the major stars come the six auspicious and six Sha stars, placed by the birth year, month and hour (see the six auspicious and six Sha stars), and the birth-year transformations, set by the stem of the birth year (see the Four Transformations).

Last come the decades: starting from the Life Palace, each palace governs ten years, and the first decade starts at the bureau number. Yang males and Yin females move forward; Yin males and Yang females move backward. The example is a Geng (Yang) year and male, so he moves forward: ages 6–15 in the Life Palace, 16–25 in the Parents Palace. A girl born at the same moment moves backward, spending 16–25 in the Siblings Palace. So a boy and a girl born in the same hour have identical natal charts but walk their decades in opposite directions.

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