Hour Stem Table for Geng 庚 Day: All 12 Hour Pillars

When the day pillar is a Geng 庚 (Gēng) day, this bazi hour stem table for Geng day gives you the final pillar. Geng is yang Metal — the axe, the ore, unrefined strength before it is filed down. It pairs with Yi under the Five Rats rule, so its day opens on the Rat hour 丙子.

The 12 hour pillars for a Geng 庚 day

Worked example

Take a Geng day birth at 16:40 — the Monkey hour (申, 15:00–16:59). The hour pillar is 甲申 (Jiǎ Shēn). The branch 申 is yang Metal, the same element as the Geng Day Master, so the chart roots its Metal firmly at the destination pillar; the 甲 Wood stem on top is Wealth the Metal can act on. A reader reads that as capability late in life, backed by resources to spend it on.

The rooting is spelled out by the hidden stems (藏干 cánggān): Shēn 申 (Monkey) conceals Gēng 庚 (Yang Metal), Rén 壬 (Yang Water) and Wù 戊 (Yang Earth). Against the Geng Day Master those are Friend (比肩 bǐjiān), Eating God (食神 shíshén) and Indirect Resource (偏印 piānyìn) — the axe’s own kind, its outlet and its backing, all inside one branch. It is a busy, self-sufficient corner of the chart, and the Monkey hour page gives the branch its full portrait.

The destination seat on a Geng day, hour by hour

Because the hour pillar is the children and later-life palace, the stem in each row seats a Ten God (十神 shíshén) there for a Geng chart:

Raw ore reads these gods differently from finished steel: a strong Geng welcomes the Rat hour’s Seven Killings as the forge that shapes it, while a weak one is battered by the same god. That judgement belongs to the Geng Metal Day Master profile and the strength guide.

Reading the pattern, and reading the clock

Two things are worth noticing before you lift a pillar off this table. First, the pattern itself: as you move down the hours the branch stays fixed by the clock, but the stem climbs one step of the ten-stem sequence at every hour, looping from 癸 back to 甲 when it reaches the end. That single motion is the whole Five Rats rule at work, and it is why the Geng-day column begins on 丙子 and closes twelve steps later on 丁亥. Yi days share Geng’s 丙子 starting point under the Five Rats rule, so the Yi day hour stem table runs through the same twelve hour pillars.

Second, the clock. The times above are true solar times, tied to the sun’s real position rather than the figure on a birth certificate. Two corrections can push a birth across an hour line. One is the longitude gap between the birth city and the meridian its time zone is officially set to — in Singapore, where clocks run on UTC+8 while the island lies nearer 104°E, civil time can lead solar time by close to half an hour. The other is the equation of time, a seasonal drift of up to about a quarter-hour either way. For a Geng-day birth logged near a boundary such as 02:58, those few minutes decide which row above is genuinely yours. The calculator linked below applies both corrections for you, which is why its result can differ from a hand count taken off raw clock time.

The late Zi (子) note for Geng days

The Rat hour is 23:00–00:59, across midnight. A birth from 23:00–23:59 on a Geng day takes the next day stem’s Zi pillar for the hour, while the day pillar stays Geng. This is the late-Zi (晚子時 wǎn zǐshí) convention, one of the few genuinely contested points in the craft — see the birth hour and hour pillar page.

Running the lookup on your own chart

Confirm the day stem first: it is the upper character of the day pillar, and it is also your Day Master — on this page it must be 庚. Then correct the recorded birth time toward solar time, match the corrected time to its double-hour, and take the pillar from the first table and the ten god from the second. A birth logged within twenty minutes of any boundary, or anywhere in the 23:00–00:59 window, stays provisional until the correction is done.

No birth time on record?

The chart is still three-quarters readable — year, month and day carry the season, the Day Master and the spouse palace — but the destination palace goes dark, so hold children and late-life claims lightly. Before settling for that, chase the time: hospital archives, a parent’s memory tied to shift changes or sunrise. If two or three candidate hours remain, each row above proposes a different pillar and a different god, and testing those proposals against the life so far is how the real one is found. Do not simply pick one to complete the grid.

What the hour pillar governs

The hour is the destination pillar — children, output, ambition, later life. It is derived, not calendrical, through the Five Rats rule (五鼠遁 wǔshǔdùn) shown whole on the master hour stem table. Its yin-Metal partner, the Xin day hour table, opens its Rat hour on 戊子 rather than Geng’s 丙子.

Let the calculator handle the derivation — plot your Geng-day chart free and read the hour pillar to the minute.