The Ten Heavenly Stems Explained

What Are Heavenly Stems?

The Ten Heavenly Stems (천간/天干, Cheongan) represent celestial energies that cycle through time. Together with the Twelve Earthly Branches, they form the 60-year cycle (육십갑자) that is fundamental to Korean and Chinese calendar systems.

Each Heavenly Stem has a distinct character that combines:

• An element (Wood, Fire, Earth, Metal, or Water)
• A polarity (Yin or Yang)

When you know someone’s Day Stem (the Heavenly Stem of their Day Pillar), you gain insight into their core personality—their Day Master.

Overview of the Ten Stems

#	Stem	Korean	Element	Polarity	Key Trait
1	甲	갑 (Gap)	Wood	Yang	Pioneer
2	乙	을 (Eul)	Wood	Yin	Diplomat
3	丙	병 (Byeong)	Fire	Yang	Radiant
4	丁	정 (Jeong)	Fire	Yin	Refiner
5	戊	무 (Mu)	Earth	Yang	Mountain
6	己	기 (Gi)	Earth	Yin	Nurturer
7	庚	경 (Gyeong)	Metal	Yang	Warrior
8	辛	신 (Sin)	Metal	Yin	Artisan
9	壬	임 (Im)	Water	Yang	Explorer
10	癸	계 (Gye)	Water	Yin	Sage

The Wood Stems

甲 (Gap/갑) - Yang Wood

The Pioneer / The Great Tree

Gap represents the mighty tree—tall, straight, and reaching for the sky. Like an oak that stands firm through storms, Gap individuals have a strong sense of direction and natural leadership qualities.

Personality Traits:

• Natural leader who takes initiative
• Straightforward and honest communication
• Strong sense of purpose and direction
• Ambitious and growth-oriented
• Can be stubborn once a path is chosen

Potential Challenges:

• May appear inflexible or uncompromising
• Can be too direct, causing friction
• Tendency to overlook small details in pursuit of big goals

In Relationships: Gap seeks partners who respect their independence while providing grounding. They thrive with someone who can match their energy and ambitions.

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乙 (Eul/을) - Yin Wood

The Diplomat / The Vine

Eul represents flexible vegetation—the vine that finds its way around obstacles rather than pushing through them. Where Gap is the oak, Eul is the willow, bending with the wind but never breaking.

Personality Traits:

• Highly adaptable and flexible
• Diplomatic and peacekeeping
• Artistic sensibility and appreciation for beauty
• Builds networks through gentle persistence
• Quietly determined

Potential Challenges:

• May be perceived as indecisive
• Can avoid necessary confrontation
• Might suppress own needs for harmony

In Relationships: Eul partners are supportive and accommodating, creating harmonious environments. They need partners who appreciate subtlety and don’t mistake gentleness for weakness.

The Fire Stems

丙 (Byeong/병) - Yang Fire

The Radiant One / The Sun

Byeong is the sun itself—bright, warm, and generous with its light. These individuals naturally illuminate any room they enter, spreading warmth and optimism.

Personality Traits:

• Charismatic and magnetic presence
• Naturally optimistic and generous
• Inspiring and motivating to others
• Honest and transparent
• Creative and expressive

Potential Challenges:

• May burn too bright and exhaust themselves
• Can be overly trusting or naive
• Tendency toward dramatics

In Relationships: Byeong partners are warm and giving, sometimes to a fault. They need partners who appreciate their generosity without taking advantage, and who help them pace their energy.

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丁 (Jeong/정) - Yin Fire

The Refiner / The Candle

Jeong is the controlled flame—a candle providing steady illumination, or a torch lighting the way through darkness. Less dramatic than Byeong’s sun, but more precise and enduring.

Personality Traits:

• Thoughtful and refined
• Excellent attention to detail
• Persistent and dedicated
• Deep thinker and analyzer
• Loyal in relationships

Potential Challenges:

• Can be overly critical (of self and others)
• Tendency toward anxiety and worry
• May get lost in details

In Relationships: Jeong partners are devoted and attentive. They show love through thoughtful actions rather than grand gestures. They need partners who appreciate their depth and don’t dismiss their concerns.

The Earth Stems

戊 (Mu/무) - Yang Earth

The Mountain / The Fortress

Mu represents the great mountain—solid, reliable, and unshakeable. These individuals provide stability and security to those around them, like a mountain sheltering a village.

Personality Traits:

• Exceptionally reliable and trustworthy
• Practical and grounded
• Strong ethical foundation
• Patient beyond measure
• Protective of loved ones

Potential Challenges:

• Can be too rigid or resistant to change
• May miss opportunities due to caution
• Sometimes appears boring to more dynamic types

In Relationships: Mu partners are the rocks you can always depend on. They need partners who value stability and don’t constantly demand change or excitement.

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己 (Gi/기) - Yin Earth

The Nurturer / The Garden Soil

Gi is the fertile soil that nurtures growth in others. Where Mu is the mountain, Gi is the valley—receptive, supportive, and enabling life to flourish.

Personality Traits:

• Natural caretaker and supporter
• Creates nurturing environments
• Methodical and organized
• Observant of others’ needs
• Humble and service-oriented

Potential Challenges:

• May neglect own needs entirely
• Can be taken for granted
• Tendency toward excessive worry

In Relationships: Gi partners create warm, supportive homes. They need recognition for their giving nature and partners who reciprocate care rather than just receiving it.

The Metal Stems

庚 (Gyeong/경) - Yang Metal

The Warrior / The Sword

Gyeong is forged steel—strong, sharp, and principled. These individuals have a clear sense of right and wrong and the courage to stand for their convictions.

Personality Traits:

• Strong sense of justice
• Decisive and action-oriented
• Competitive and driven
• Courageous under pressure
• Direct and honest

Potential Challenges:

• Can be confrontational
• May see issues too black-and-white
• Risk of being harsh or cutting

In Relationships: Gyeong partners are protective and loyal. They need partners who can handle their intensity and who value straightforward communication.

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辛 (Sin/신) - Yin Metal

The Artisan / The Jewel

Sin is refined metal—the polished gem, the delicate jewelry. These individuals have an appreciation for quality and beauty, with high standards for themselves and their work.

Personality Traits:

• Refined aesthetic sensibility
• Strives for perfection
• Sensitive and perceptive
• Elegant in presentation
• Detail-oriented

Potential Challenges:

• Can be overly critical or picky
• Tendency toward melancholy
• May seem cold or distant

In Relationships: Sin partners appreciate refinement and quality in relationships. They need partners who understand their sensitivity and don’t dismiss their high standards as mere pickiness.

The Water Stems

壬 (Im/임) - Yang Water

The Explorer / The Ocean

Im is the vast ocean—powerful, deep, and ever-moving. These individuals have big-picture thinking and the resourcefulness to navigate any situation.

Personality Traits:

• Strategic and intelligent
• Highly resourceful
• Adventurous and willing to take risks
• Excellent at seeing possibilities
• Versatile and adaptable

Potential Challenges:

• Can be calculating or manipulative
• May struggle with commitment
• Risk of appearing cold or detached

In Relationships: Im partners bring adventure and possibilities. They need partners who can match their depth and who don’t try to restrict their expansive nature.

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癸 (Gye/계) - Yin Water

The Sage / The Rain

Gye is the gentle rain—nourishing, subtle, and essential for growth. Like water that seeps into every crack, these individuals have deep intuition and understanding.

Personality Traits:

• Highly intuitive and perceptive
• Deep inner wisdom
• Imaginative and creative
• Compassionate and understanding
• Spiritual or philosophical

Potential Challenges:

• Can be overly passive
• Tendency toward escapism
• May be difficult to truly know

In Relationships: Gye partners offer depth and intuitive understanding. They need partners who appreciate their subtle nature and don’t demand constant external expression.

How Stems Interact

When analyzing compatibility or relationships in Saju, practitioners examine how different stems interact:

• Same element, different polarity: Natural understanding with complementary expression
• Generating relationship: One supports/nurtures the other
• Controlling relationship: One restrains/challenges the other

Find Your Stem

Ready to discover your Day Stem? Use our Saju Calculator to generate your full chart and learn which of the Ten Heavenly Stems defines your Day Master.

Continue Learning

• The Twelve Earthly Branches
• Understanding the Day Master
• Five Elements Deep Dive