Eight characters, and the arithmetic behind them
The chart on the front page shows three of your four pillars. This is the full set, the element count across them, and the ten-year cycles that run off the month pillar. Every figure here is computed from the position of the sun at the moment you were born — nothing is looked up in a table.
The four pillars
Read right to left in the traditional order, the day pillar is the one that stands for you. Times are read as Beijing time; there is no correction for the longitude you were actually born at, which a traditional almanac would apply and which can move the hour pillar by one place near the boundaries.
Element balance
This is a count, not a verdict. Every character is counted once, whether it sits in the year or the hour. Traditional analysis weights them by position and by season, and the schools disagree about how — so the weighting is not done here rather than done arbitrarily. What is shown is what can be counted.
Ten-year luck cycles
| From age | Pillar | Reading | Element |
|---|
How each figure is worked out
- Day pillar. The Julian day number of the date, stem (JDN + 9) mod 10 and branch (JDN + 1) mod 12. Checked against 1 October 1949, a known Jia‑Zi day.
- Solar longitude. The low‑precision series from the Astronomical Almanac, accurate to about a hundredth of a degree, which is roughly a quarter of an hour of time.
- Year pillar. Switches at the start of spring — the moment the sun reaches 315° — not on a fixed calendar date, so births in the first days of February fall on the correct side.
- Month pillar. The solar terms cut the year into twelve 30° months. The branch follows the month, the stem follows the year stem by the five‑tigers rule: (year stem × 2 + 2 + month index) mod 10.
- Hour pillar. Two hours to a branch, starting at 23:00. After 23:00 the stem is taken from the following day, which is the late Zi‑hour convention.
- Luck cycles. Direction from the year stem and sex; the start age is the distance from birth to the bounding solar term, at the traditional three days to a year.