Heavenly Stems and Earthly Branches: The Building Blocks of Your Saju Chart
Read the ten stems and twelve branches, check their primary element labels, and follow a worked count without confusing symbols with measurable energy.
Lucky By Birthday · Content revised 2026-09-13
Heavenly Stems and Earthly Branches are ordered sets of calendar symbols. The names are traditional terminology. Calling a symbol heavenly or earthly does not mean that this calculator detects a physical energy in the sky, ground, or person. Start by recognizing the characters and checking their position in a pair.
The ten stems in order are 甲, 乙, 丙, 丁, 戊, 己, 庚, 辛, 壬, 癸. Their primary element pairs are 甲·乙 = Wood, 丙·丁 = Fire, 戊·己 = Earth, 庚·辛 = Metal, 壬·癸 = Water. The first of each pair is classed yang and the second yin. These are symbolic labels, not measurements of temperament.
The twelve branches in order are 子, 丑, 寅, 卯, 辰, 巳, 午, 未, 申, 酉, 戌, 亥. For the visible-element method used here, 寅·卯 = Wood, 巳·午 = Fire, 丑·辰·未·戌 = Earth, 申·酉 = Metal, and 子·亥 = Water. The unequal number of branch labels per element is one reason this simple count should not be treated as a calibrated personality scale.
Apply the lookup to the public 2000-01-01 noon example. Its Month pair is 丙子: 丙 contributes one Fire and 子 contributes one Water. Its Day pair is 戊午: 戊 contributes one Earth and 午 one Fire. The Day Master is 戊 because of its position, not because Fire or Earth has the largest total. The calculator's ledger shows the same lookup for every visible character.
Hidden stems are a different layer of traditional interpretation. A method that decomposes a branch into additional stems, weights the season, or counts stem relationships can produce a different distribution from this visible-character method. Before comparing two charts, ask for the counting rule and denominator. Our one-label-per-character view deliberately does not present itself as that fuller analysis.
To check pair order, advance one step in both lists at once. 甲子 is followed by 乙丑, then 丙寅. After 癸酉 comes 甲戌 because the stem list has restarted while the branch list has two entries left. The sequence repeats after sixty steps. This exercise checks the structure of labels; attaching a forecast or judgment about a person would be an additional, unverified claim.
Why the system has sixty pairs, not 120
The ten Heavenly Stems and twelve Earthly Branches do not combine in every possible way. Both sequences advance together, preserving their yin-or-yang parity. A yang stem pairs with a yang branch and a yin stem with a yin branch. Because the least common multiple of 10 and 12 is 60, the starting pair returns after sixty steps. That arithmetic produces the sexagenary cycle used for years, months, days, and hours in East Asian calendars.
You can audit the sequence without interpreting it. Start with 甲子, advance both lists by one place to 乙丑, and continue. After 癸酉, the stem list restarts at 甲 while the branch list continues to 戌, giving 甲戌. This mechanical exercise shows why combinations such as 甲丑 are absent from the standard cycle: their yin-yang parity does not match.
Element labels are a second layer placed on the symbols. The ten stems divide into Wood, Fire, Earth, Metal, and Water with a yin and yang form of each. The twelve branches have primary element associations, but traditional practice may also discuss hidden stems and seasonal strength. Lucky By Birthday’s visible-element chart counts only the displayed stem and primary branch element, so it should not be confused with a full weighting system.
A three-minute sequence check
- Confirm that stems repeat every 10 steps and branches every 12.
- Check that yin and yang parity matches within each valid pair.
- Use the least common multiple, 60, to identify a full cycle.
- Keep symbol assignment separate from later interpretive meaning.
Stem and branch labels are the calendar engine’s output. Element percentages count their primary visible labels only; hidden stems and seasonal weighting are excluded. The worked example lets you check the count.