Purple Star Astrology vs BaZi
Both start from the moment of birth, and both are Chinese astrology, but they use different calendars, build different charts and read them in different ways. BaZi (Four Pillars) is eight characters; Purple Star Astrology (Zi Wei Dou Shu, 紫微斗数) is a ring of twelve palaces full of stars.
Side by side
| BaZi | Purple Star | |
|---|---|---|
| What it needs | Birth date, time and place (for true solar time), and sex (for which way the ten-year periods run). | The same. |
| Which calendar | The solar terms: the year turns at the Start of Spring (Li Chun, 立春), each month at a solar term. | The lunar calendar: stars are placed by lunar month and day. |
| What it builds | Four pillars — year, month, day and hour — each a stem and a branch: eight characters. | A ring of twelve palaces, with fourteen main stars and many lesser ones placed in them. |
| The centre of the chart | The day master: the stem of the day you were born. | The Self palace (Ming Gong, 命宫) and the stars in it. |
| How it is read | The balance of the five elements, and the ten gods — what every other character is to the day master. | Which stars sit in which palace — each palace one area of life — and the four transformations the birth year brings. |
| Ten-year periods | Luck pillars (Da Yun, 大运): one pillar for each ten years. | Decades (Da Xian, 大限): ten years in each palace in turn. |
| How much the birth hour matters | It sets one pillar of the four. Without the hour, the day master is still known. | It sets the Self palace, and when that moves the whole ring turns with it. |
| The classic texts | Yuan Hai Zi Ping, San Ming Tong Hui, Di Tian Sui, Qiong Tong Bao Jian, Zi Ping Zhen Quan. | Zi Wei Dou Shu Quan Shu (紫微斗数全书). |
One birth, read both ways
15 June 1975, 8:00 in the morning, Kuala Lumpur. That year the clocks there ran on UTC+7:30, so the true solar time is 07:16 — the Dragon hour.
BaZi
By the solar terms, 15 June is past Grain in Ear, so this is the Horse month. The four pillars: Wood Rabbit, Water Horse, Water Dragon, Wood Dragon (乙卯 壬午 壬辰 甲辰).
Day master: Yang Water (Ren, 壬).
Purple Star
By the lunar calendar this is the 6th day of the 5th month (一九七五年五月初六).
In the Self palace: The Blessing (Tian Tong, 天同) and The Elder (Tian Liang, 天梁). Type: Ji Yue Tong Liang (机月同梁).
Both are computed by this site as the page loads. Worked out with today’s UTC+8 instead, the hour would be the Rabbit: in BaZi that changes one pillar of four; in Purple Star Astrology the Self palace moves, and the whole reading with it.
Which should I use — and which is more accurate?
They answer different questions. BaZi suits “what am I made of, what balances me, and when do things turn”; Purple Star Astrology suits looking at a life area by area — marriage, career and money each have a palace of their own. Many people read both.
As for accuracy: neither has been shown to predict anything, and this site offers both for reflection. What is certain is that both depend on the birth time being right — get the time wrong and the chart is not yours. If you are unsure of the hour, your BaZi day master stands without it (find yours), and all twelve possible charts shows what each hour would give.