Four Pillars, Eight Characters
Saju (四柱) literally means four pillars. Each of the year, month, day, and time of birth is established as one pillar, and two characters are written for each pillar. Thus, there are a total of eight characters, which is referred to as the natal chart.
| Pillar | What does it come from? | Two Characters |
|---|---|---|
| Year Pillar (年柱) | Year of birth | Heavenly Stem + Earthly Branch |
| Month Pillar (月柱) | Month of birth | Heavenly Stem + Earthly Branch |
| Day Pillar (日柱) | Day of birth | Heavenly Stem + Earthly Branch |
| Time Pillar (時柱) | Time of birth | Heavenly Stem + Earthly Branch |
The upper characters are called heavenly stems (天干), and the lower characters are called earthly branches (地支). There are ten heavenly stems and twelve earthly branches. The twelve earthly branches are commonly referred to as zodiac signs.
Among them, one character points to me.
Not all eight characters carry the same weight. The heavenly stem of the day of birth, specifically the upper character of the day pillar, points to myself. This is called the day stem (日干).
Year Pillar
Heavenly Stem
Earthly Branch
Root · Zodiac Sign
Month Pillar
Heavenly Stem
Earthly Branch
Season · Strength
Day Pillar
Heavenly StemDay Stem = Self
Earthly BranchDay Branch = Spouse Palace
Self · Spouse Palace
Hour Pillar
Heavenly Stem
Earthly Branch
Later Years · Usage
What this service shows mostly derives from this one character — the interpretation of tendencies, the strength of the five elements, the energy currently needed, and today's fortune are all measured based on the Day Stem. The remaining seven characters indicate 'what environment the Day Stem is placed in'.
Divided by Solar Terms, Not Calendar Year
A saju year does not change on January 1st but rather at Ipchun (around February 4th). The month also divides based on solar terms.
Thus, those born in January and early February receive the Year Stem of the previous year. This is where the common misunderstanding about zodiac signs arises. The same applies if you input a lunar birthday — it is converted back to solar and then divided by solar terms.
You Can Read It Even Without Knowing the Birth Time
If you do not input the time, the reading will be based on the three pillars and six characters, excluding the Hour Pillar. We do not guess missing values — arbitrarily assigning an Hour Pillar can disrupt the strength of the five elements, leading to incorrect conclusions instead of potentially accurate ones.
If you know the time, it is better to include it. Since two characters are added among the eight, the strength and assessment of the five elements can change. However, we do not use the clock time directly but instead use True Solar Time.
