Saju (四柱) literally means 'four pillars.' The four pillars are built from the year, month, day, and hour of a person's birth. Each pillar consists of two characters — one from the Heavenly Stems (天干, cheongan) and one from the Earthly Branches (地支, jiji) — giving eight characters in total. This is why the practice is also called sajupallja (四柱八字), or 'four pillars, eight characters.'
Heavenly Stems and Earthly Branches — The Building Blocks
The ten Heavenly Stems are: Gap (甲), Eul (乙), Byeong (丙), Jeong (丁), Mu (戊), Gi (己), Gyeong (庚), Sin (辛), Im (壬), and Gye (癸). The twelve Earthly Branches are: Ja (子), Chuk (丑), In (寅), Myo (卯), Jin (辰), Sa (巳), O (午), Mi (未), Sin (申), Yu (酉), Sul (戌), and Hae (亥). You may recognize the twelve Earthly Branches as the animals of the zodiac cycle — Ja is the Rat, Chuk is the Ox, In is the Tiger, and so on.
While the ten Stems and twelve Branches can theoretically combine in 120 ways, traditional practice uses exactly sixty combinations known as the Sixty Cycle (六十甲子, yuксип гapja). This sixty-year cycle forms the backbone of the East Asian lunisolar calendar. When all four pillars are established — for the year, month, day, and hour — the eight-character chart is complete and ready to be read.
The Five Elements and Their Interactions
The Five Elements (五行, ohaeng) are Wood (木), Fire (火), Earth (土), Metal (金), and Water (水). Each Heavenly Stem and Earthly Branch is associated with one of these five energies. By mapping all eight characters onto the Five Elements, a reader can see at a glance which energies are dominant in a person's chart and which are absent or weak. This balance — or imbalance — is the central focus of saju analysis.
The Five Elements interact in two fundamental ways. The generative cycle (相生, sangsaeng) describes how each element nurtures the next: Wood feeds Fire, Fire creates Earth, Earth yields Metal, Metal holds Water, and Water nourishes Wood. The controlling cycle (相剋, sanggeuk) describes the opposing dynamic: Wood breaks Earth, Earth absorbs Water, Water extinguishes Fire, Fire melts Metal, and Metal cuts Wood. A skilled reader uses these relationships to identify which energies need strengthening or tempering in a person's chart.
Saju in Korean History — From Goryeo to Joseon
Saju scholarship entered the Korean peninsula during the Goryeo dynasty and flourished during the Joseon period (1392–1897), when it was studied under the name myeongrihak (命理學), meaning 'the study of fate and principle.' The state bureau Gwansanggam (觀象監) handled astronomical and calendrical matters including almanac production, creating an institutional context for saju-related knowledge. During the later Joseon period, scholars closely studied Chinese classical texts such as Dichansui and Zìpíng Zhēnquán, gradually developing distinctly Korean interpretive schools.
One practical note worth knowing is the role of the birth hour (時柱, sichu). The traditional day is divided into twelve two-hour periods called sikchin, beginning at midnight with Ja-si (子時, 11 PM–1 AM), followed by Chuk-si (丑時, 1–3 AM), and so on. Additionally, when calculating the year pillar and month pillar, the year changes at Ipchun (立春, the solar term for the start of spring, typically around February 4–6) rather than on January 1. This means someone born in January may technically belong to the previous year's stem-branch cycle in saju terms. If you do not know your exact birth time, noon is traditionally used as a default — a convention also followed by our Saju Quick Read test.
Using Saju as a Modern Tool for Self-Reflection
In contemporary Korea, saju is often engaged as a lens for gentle self-reflection rather than as a deterministic oracle. Many people browse a quick saju reading the same way others might take a personality questionnaire — as a starting point for thinking about temperament, strengths, and blind spots. The tradition is rich enough to reward serious study, but light enough to enjoy casually. The important caveat, shared by most reputable practitioners, is that saju describes tendencies and contexts, not fixed outcomes. Your choices always matter more than the chart.
The Saju Quick Read tool on Today's Me draws on these foundational concepts. Enter your birth year, month, day, and optionally your hour, and the tool maps your chart across the Five Elements and reads the temperament encoded in your day pillar. It is not a substitute for a consultation with a knowledgeable practitioner, but it offers a friendly introduction to a tradition that has accompanied Korean cultural life for centuries. Think of it as a small mirror, not a verdict.