Heavenly Stems and Earthly Branches: The Building Blocks of Your Saju Chart
A comprehensive guide to the 10 Heavenly Stems (천간) and 12 Earthly Branches (지지) in Korean Saju.
Lucky By Birthday Editorial Team · Editorially reviewed 2026-08-24
The Heavenly Stems (천간, Cheon-gan) and Earthly Branches (지지, Ji-ji) are the alphabetical building blocks of Korean Saju. Just as the Latin alphabet combines letters into words and sentences, these 22 cosmic symbols combine into pillars and charts that tell the story of your destiny. Understanding them individually is essential to reading any Saju chart.
The 10 Heavenly Stems represent celestial energy — the pure, archetypal expression of the Five Elements in both Yin and Yang forms. They cycle in order: 甲 (Gap), 乙 (Eul), 丙 (Byeong), 丁 (Jeong), 戊 (Mu), 己 (Gi), 庚 (Gyeong), 辛 (Sin), 壬 (Im), 癸 (Gye). Each stem carries the essence of its element in its purest form — when you encounter a Heavenly Stem in your chart, you're reading the celestial intention for that pillar of your life.
The 12 Earthly Branches represent terrestrial energy — the practical, manifested expression of cosmic forces on Earth. They correspond to the 12 animals of the zodiac: 子 (Ja, Rat), 丑 (Chuk, Ox), 寅 (In, Tiger), 卯 (Myo, Rabbit), 辰 (Jin, Dragon), 巳 (Sa, Snake), 午 (O, Horse), 未 (Mi, Sheep), 申 (Sin, Monkey), 酉 (Yu, Rooster), 戌 (Sul, Dog), 亥 (Hae, Pig). Each Branch contains hidden Stems within it, adding layers of complexity.
The concept of "hidden Stems" (지장간, Ji-jang-gan) is one of Saju's most sophisticated features. Each Earthly Branch contains one to three hidden Heavenly Stems that represent dormant energies within that Branch. For example, the Tiger Branch (寅) contains hidden Yang Wood (甲), Yang Fire (丙), and Yang Earth (戊). These hidden Stems can be activated by other elements in the chart or by the current cosmic period, suddenly bringing new energies to the surface.
When a Heavenly Stem sits atop its compatible Earthly Branch, the pillar is said to be "rooted" — the celestial intention has solid earthly support. For instance, Yang Wood (甲) sitting on the Tiger Branch (寅, which contains hidden Yang Wood) is strongly rooted. This person's Wood energy is authentic, deeply supported, and naturally powerful. Conversely, an "unrooted" Stem — like Yang Fire sitting on a Water-heavy Branch — may indicate energy that is aspirational but challenging to manifest.
The sexagenary cycle (육십갑자, Yuksip-gapja) combines the 10 Stems with the 12 Branches to create 60 unique Stem-Branch pairs that cycle through years, months, days, and hours. This 60-year cycle is fundamental to East Asian timekeeping and is why certain year combinations repeat every 60 years. Your birth year's Stem-Branch pair is the most commonly known aspect of your Saju, but it's just the beginning.
Special relationships between Branches add further depth to chart interpretation. "Combinations" (합, hap) occur when certain Branches meet and transform their elemental energy. "Clashes" (충, chung) occur when opposing Branches create friction. "Punishments" (형, hyeong) indicate karmic challenges. "Destructions" (파, pa) and "Harms" (해, hae) indicate other specific types of difficulty. Master Saju readers weave all these relationships together into a coherent narrative.
For a beginning student, the key takeaway is that Stems and Branches combine across the available pillars. Many people can share the same calendar labels, so a chart is not a unique identifier and should not be treated as proof of personality. Its value is as a structured way to learn the traditional vocabulary and ask reflective questions.