Your twelve palaces with the fourteen major stars, the Life and Body palaces, the four transformations of your year stem, and the ten-year decade limits.
Lunar date from two independent calendars that must agree · checked against two outside engines · late-zi births flagged
Zi Wei Dou Shu runs on the lunar calendar, not the solar one, and that is where most free calculators go wrong. The position of Zi Wei itself is derived from the lunar day and the Ju number; get the lunar day wrong by one and every star in the chart moves. This page asks two unrelated calendar libraries for the same date and refuses to draw anything if they disagree.
The star placements were checked against two outside engines that share no code with this one or with each other, over randomly generated birth dates. Where a rule could not be confirmed by at least one of them, it was not shipped.
A birth from 23:00 onward falls in the zi hour, which belongs to the next day in some schools and the current day in others. This is not a rounding detail: it moves Zi Wei and rebuilds the chart. Rather than pick a side quietly, the page computes the same-day reading, tells you it did, and gives you a checkbox for the other one. If the two look very different, that is worth knowing before you act on either.
Three things move a Zi Wei chart, and sites disagree on all three. The first is the lunar day: Zi Wei's own position is counted from it, so a calendar that is one day out moves every star. The second is the birth hour branch, which sets the Life palace. The third is a birth from 23:00 onward, where schools split over whether the lunar day has already turned. This page states which lunar day it used and offers the other reading as a checkbox rather than deciding for you.
The Ju, or element class, is read from the stem of the Life palace and its branch through the nayin table, and it comes out as Water 2, Wood 3, Metal 4, Earth 5 or Fire 6. The number is a divisor: it decides where Zi Wei falls for a given lunar day, and it also sets the age at which the first decade begins. It is not a measure of how much of that element you have.
No. They share the stems, branches and the lunar-solar calendar, and nothing else. BaZi works with the balance of five phases across four pillars. Zi Wei places named stars into twelve palaces, each palace standing for an area of life. The two answer different questions, and a chart can look strong in one and unremarkable in the other.
You need the two-hour branch, which is more forgiving than a Vedic ascendant but less forgiving than BaZi. An error of an hour usually changes nothing; an error that crosses an odd hour boundary moves the Life palace and the whole chart with it. If the time is unknown, the page still computes, but the palace layout is a guess and the honest reading is the year and lunar date alone.
Hua Lu, Hua Quan, Hua Ke and Hua Ji — wealth, power, fame and trouble. The year stem picks four stars and marks them. Where they land matters more than the stars themselves: the same star carries a different weight in the Career palace than it does in Health. The trouble mark is not a prediction of misfortune, it is where the chart says friction shows up.