The chart is calculated,
not generated.

The calendar underneath

Pillars are drawn from the classical Chinese calendar (만세력 / 万年暦), using astronomical solar terms rather than calendar months. Your month pillar changes at the solar term, not on the first of the month — so someone born on 4 February may belong to the previous month's pillar.

For the year and month pillars, the birth instant is converted to the Asia/Shanghai reference clock before the solar-term boundary is evaluated. This matters most for births close to a term boundary.

True solar time

True solar time is an optional experimental correction and is off by default. When it is off, the chart uses the recorded civil clock time without this adjustment.

When you choose to turn it on, we correct for two things: the gap between longitude and the centre of the timezone, and the equation of time — the yearly wobble caused by the Earth's tilted, elliptical orbit.

We do not ask for your exact birthplace, so the longitude used is a representative one for the timezone you select — Asia/Seoul is read at Seoul's longitude. A birth elsewhere in the same timezone carries an error of a few minutes: Busan differs from Seoul by about 8 minutes of solar time.

For Seoul under UTC+9, the longitude part is about −32 minutes. The equation of time is not a fixed ±4 minutes: in our astronomical approximation it varies through the year by roughly −14 to +16 minutes, so the combined correction changes with the birth date.

If you opt in, be aware of what the approximation can move. Near an hour or midnight boundary it may change the hour pillar or move the local solar date into the previous day, changing the day pillar and Day Master. The result records whether the option was actually applied and the minutes used.

Where the day begins

This is the single most contested rule in the tradition, so we state our choice plainly: the 子 (Rat) hour begins at 23:00, but the day pillar changes at midnight.

That means a birth at 23:30 is in the 子 hour while retaining the current civil day's day pillar. Other schools roll the day pillar over at 23:00 instead. Neither is 'wrong' — they are different lineages, and a chart calculated under the other convention will differ from ours for births between 23:00 and midnight.

Luck cycles

Luck pillars (대운 / 大運) run forward or backward depending on the polarity of your year stem and your sex — forward for yang-male and yin-female, backward otherwise. The starting age comes from the distance to the neighbouring solar term, at the traditional three-days-to-one-year ratio.

Annual pillars (세운 / 歳運) are then read against your Day Master, and the year-ahead reading breaks the year into twelve solar-term months rather than calendar months.

How the elements are weighted

The displayed element balance gives each visible stem and branch a weight of 2 and each hidden stem a weight of 1. Seasonal support is not added to those percentages. Ten Gods are derived for the other visible stems and the hidden stems from their element and polarity relationship to the Day Master.

A separate beta support heuristic adds peer/resource weight, seasonal support, and roots found in branches, then labels the Day Master support-light, balanced, or support-heavy. The two least represented elements are shown only as balancing candidates, not as a definitive governing-element verdict.

How phone numbers are ranked

For Korean and Japanese mobile formats, we read the four-digit block a customer commonly chooses; for other formats, we use the last four digits. Digits 1–2 map to Wood, 3–4 to Fire, 5–6 to Earth, 7–8 to Metal, and 9–0 to Water.

The chart's Day-Master support label determines which elements are welcomed or already excessive. Each candidate starts at 50: element fit, adjacent generating or controlling flow, and element concentration each add or subtract weighted points. The result is clamped to 6–96, and ties favor a broader element spread and smoother flow. This is a transparent beta ranking for reflection, not a claim that a number causes events.

공망 (空亡) — the unpaired branches

Ten stems turning against twelve branches leaves two branches without a stem in every run of ten. Those two are the 공망 of that run: 甲子 through 癸酉 leaves 戌 and 亥, 甲戌 through 癸未 leaves 申 and 酉, and so on through the six runs. Japanese readers know the same figure as 空亡 or 天中殺.

We read it from the DAY pillar. Reading from the year pillar is also traditional and some readers use it; we chose the day because it is the seat of the person, which is what a personal reading is asking about. A chart calculated from the year will differ from ours whenever the two pillars fall in different runs.

We do not write it as loss. The tradition often teaches 공망 as emptiness or things coming to nothing, and a paid reading that repeats that is selling fear. In our readings a pillar in 공망 marks an area where the usual external measures land softly and satisfaction has to come from the thing itself. When no pillar falls in 공망, the reading says nothing about it rather than reporting an absence.

십이운성 (十二運星) — and which school we follow

The twelve stages borrow the arc of a life — conceived, carried, born, coming of age, in office, at the peak, then easing off and finally put away — and ask where your Day Master stands when it meets each branch in your chart. Each stem has a 장생 (長生) point it begins from, and walks the twelve stages round the branches from there.

The schools split on the yin stems. Under 음양순역 the yang stems walk forward and the yin stems walk backward from their own 장생 — 甲 begins at 亥 going forward, 乙 begins at 午 going backward. Under 양포태 a yin stem has no separate cycle at all and simply reads its yang partner's table. For a yin Day Master the two disagree on every single branch.

We use 음양순역, and the reason is about you rather than the doctrine: it is the table printed in Korean 만세력 and in Japanese 四柱推命 references, so it is what you will see if you check us against any other app. Where your Day Master is yin, the reading names the other school's stage in passing rather than pretending the question is settled.

The personal reading uses it on the four branches you were born with. The year-ahead reading uses it on the branch you are walking through — your current luck pillar, the year itself, and each of the twelve solar-term months. That is the difference between the two products in one line: one asks where you stand, the other asks what you are standing on this year.

Four of the twelve stages are named after sickness, dying, the grave and being cut off. We do not write them as omens, and this is not softening — it is what the figure actually says. A stage describes how much footing the STEM has on that BRANCH, not what happens to the person. A day master at 제왕 with nothing to spend that strength on is harder to live with than one at 양.

The free tools that read your chart

Lucky Colour: the five cardinal colours (오방색) are fixed by tradition — 청 for Wood, 적 for Fire, 황 for Earth, 백 for Metal, 흑 for Water. We take the element your chart leans on for balance and show a colour carrying it. Which modern shade sits under which cardinal colour is our judgement, and it is written out in the source rather than hidden.

Lucky Day: five of the seven weekdays are named after the five planets that are the five elements — 화 Mars, 수 Mercury, 목 Jupiter, 금 Venus, 토 Saturn. The element your chart leans on already has a day. Sunday and Monday belong to the sun and the moon, which are not among the five, so they are never the answer and the reading says why.

Today's Fortune: the day's own pillar is laid over your natal chart and counted as two parts against the chart's eight — one number, chosen by us and declared in the code as natal-8-daily-2-beta. Whichever element is lightest after that is what the day is asking for, and it gives the colour, the digits and the direction. It changes as the day pillar changes.

Moving Day (손 없는 날) is not a chart reading at all. It is a rule on the lunar calendar — every date ending in 9 or 0 — and the answer is the same for everybody. We label it as tradition rather than calculation for exactly that reason.