← Back

Si Hua From the Month Stem — What Most Zi Wei Calculators Get Wrong

· Zi Wei Charts

Why this matters

If you have ever generated a Zi Wei Dou Shu chart on two different websites and gotten two different Si Hua attributions — "this app says Hua Ke lands on Tai Yin, but the other one says it lands on Tian Fu" — you are looking at a real, open disagreement among schools, not a bug. The disagreement has been active for more than a century and is not going to be resolved by one more app picking a side. What you can do is understand what the two sides are claiming and pick a school deliberately.

This post is for readers who have already encountered Si Hua (四化, the Four Transformations) and want to know why the values they see differ from another source. If Si Hua is unfamiliar, the short version is: four named transformations — Hua Lu (化祿, Prosperity), Hua Quan (化權, Authority), Hua Ke (化科, Knowledge / Reputation), and Hua Ji (化忌, Obstruction) — each attach to one of the fourteen major stars based on a Heavenly Stem (天干) in your birth. Where these transformations land is one of the three or four most consequential readings in a whole chart.

The dispute is about which stem drives the attribution.

The two schools

The year-stem method

Most freely-available online calculators, and many popular Chinese paperback guides, derive Si Hua from the year stem — the Heavenly Stem of the pillar of your birth year. This is the method you will see if you search for a Si Hua table in most introductory texts and the method that most software defaults to.

The year-stem method is compact: your year has one stem, and you look up the four transformations in a single row. It is pedagogically convenient and has a long tradition, especially in San He school practice.

The month-stem method (Kwok Man Ho, Zhongzhou)

Kwok Man Ho and Martin Palmer, in The Complete Book of Chinese Horoscopes (Sunburst Books, 1995, ISBN 978-1857781816, pp. 294–295), teach the Si Hua attribution from the month stem — the Heavenly Stem of the pillar of your birth lunar month. This aligns with the Zhongzhou (中州) school tradition and is documented at length in the Hong Kong and Taiwan practitioner literature.

The month-stem method is not an obscure lineage; it is a mainstream school choice that simply did not make it into as many free online tools, because free online tools tend to implement whichever table is easiest to find. Kwok Man Ho's English-language reference is one of the few English sources that teaches the method rigorously, which is why we use his table as our authoritative source.

Where the two methods agree

For seven of the ten Heavenly Stems, the year-stem and month-stem methods produce identical Si Hua attributions. The stems Jia (甲), Yi (乙), Bing (丙), Ding (丁), Ji (己), Xin (辛), and Gui (癸) are settled across all major schools — whichever method you use, you will get the same four transformations.

This is why the debate is often invisible to casual users: most charts, most of the time, look the same under either method. The disagreement only surfaces for three specific stems.

Where they disagree

The three disputed stems are Wu (戊), Geng (庚), and Ren (壬). The disagreement is specifically on the Hua Ke (化科, Knowledge / Reputation) attribution for these three stems.

Here is the breakdown, drawn directly from our methodology table:

Stem Wu (戊)

  • Most schools (year-stem tradition): Hua Ke lands on You Bi (右弼), the minor assistant star.
  • Zhongzhou / Kwok Man Ho (month-stem tradition): Hua Ke lands on Tai Yang (太陽), a major Northern Dipper star.

The practical difference is large. You Bi is a minor star — helpful when it is there, but it does not carry the reading's weight. Tai Yang is a major star with its own strong archetypal meaning. Hua Ke on Tai Yang is a very different signature in a chart than Hua Ke on You Bi; one says "your reputation flows through the domain of radiance, visibility, and public authority," the other says "your reputation gets a quiet assist from a supporting star."

Stem Geng (庚)

This is the most contested stem; there are three different traditions:

  • Quan–Ji tradition: Hua Ke lands on Tai Yin (太陰).
  • Quan–Shu tradition: Hua Ke lands on Tian Tong (天同).
  • Zhongzhou / Kwok Man Ho (month-stem): Hua Ke lands on Tian Fu (天府).

All three are well-attested in the classical and modern literature. This is the stem where serious practitioners most commonly disagree, and where the choice of school matters most. Zi Wei Charts follows the Zhongzhou / Kwok Man Ho attribution because it is what our reference teaches.

Stem Ren (壬)

Two traditions here:

  • Quan–Ji tradition: Hua Ke lands on Zuo Fu (左輔).
  • Quan–Shu tradition: Hua Ke lands on Tian Fu (天府).

Zhongzhou / Kwok Man Ho aligns with the Quan–Shu tradition on Ren.

How to tell which method your chart used

If you are comparing two charts that disagree on Si Hua, do this:

  1. Look up your year stem and month stem in the BaZi (Four Pillars) section of each chart. Both are usually displayed.
  2. If the disagreement is on one of Wu / Geng / Ren, and one chart used the year stem while the other used the month stem, that is the source.
  3. Check the Hua Ke star specifically. If the Hua Lu, Hua Quan, and Hua Ji attributions agree but Hua Ke differs, you are almost certainly looking at the school split on Wu, Geng, or Ren.

If the Hua Lu, Hua Quan, or Hua Ji attributions also differ, check first whether your year stem and month stem are different — if they are, and the apps use different methods, all four transformations may land differently.

Does it actually matter in your chart?

It matters exactly to the extent that one of the three disputed stems is either your year stem or your month stem. For the seven undisputed stems, both methods produce the same chart, and this whole debate is academic.

For birth years or birth months that fall on Wu, Geng, or Ren, the difference is material and can change the reading substantially. The most dramatic case is Geng-month with the Quan–Ji / Quan–Shu / Zhongzhou three-way split: you can get Hua Ke on Tai Yin (emotional inner life), Tian Tong (emotional ease), or Tian Fu (material stability), and those are three different life-reading emphases.

Our recommendation if you are genuinely uncertain: generate the chart under both methods and compare them. A practitioner who has used Zi Wei for decades can often tell which method matches a lived life better by reading both charts in light of the native's actual biography. That empirical read is what convinces most serious practitioners of one school over the other.

What Zi Wei Charts uses

We use the month-stem method, following Kwok Man Ho's 1995 reference (pp. 294–295), which aligns with the Zhongzhou school for the three disputed stems. This is documented on our methodology page with the full attribution table. The choice is deliberate: we believe the month-stem derivation is more internally consistent with the rest of the Zi Wei chart structure (which is already month-and-hour-driven, not year-driven), and the English-language scholarship behind it is the most rigorous we could cite.

If you prefer the year-stem method for any reason — you are following a specific teacher, or you want to cross-reference with an app that uses it — the best we can offer is transparency: our method is documented, and you can always generate a chart here and a chart elsewhere and compare them with your eyes open.

The takeaway

Si Hua disagreements between apps are almost always a school split, not a calculation error. The split affects only three of the ten Heavenly Stems (Wu, Geng, Ren), but for those stems the difference is real. Knowing which school your calculator uses is part of knowing what you are reading.

Generate your Zi Wei Dou Shu chart with our month-stem Si Hua. The methodology page has the full attribution table including the disputed stems, and the primer on reading your Ming palace shows how Si Hua on the Ming star changes the reading.