Open a chart for the first time and it is a screen full of symbols with no obvious place to start. This page breaks it into five steps: the nine directions, the five symbols in a cell, which cell is you, how cells connect, and how to ask a question worth casting for. Read it once and you can start.
In one line: it turns the present moment into a map of directions. The moment you cast is converted into stems and branches; the solar term and its three periods fix the Yang Dun or Yin Dun cycle and the chart number; then the Nine Stars, the Eight Gates, the Eight Deities and the heaven/earth stems are laid into the nine palaces by rule.
What matters is that this derivation is deterministic: the same moment at the same longitude gives everyone the same chart. So “was it cast correctly” can be checked, and there is no room for interpretation in it — the room for interpretation comes later, in the reading.
Where it comes from: Qimen Dunjia (often written Qi Men Dun Jia) grew out of the shi-boards used by Han-dynasty military planners to time journeys, pick moments and position troops; it was later grouped with Liuren and Taiyi as the three classical Chinese time-and-direction methods. What it can do for you is break a matter into parts — who is host and who is guest, whether the current runs with you right now, which direction meets the least resistance, whether to move now or wait. It does not predict the future, and it does not decide for you.
The chart is nine cells, laid out with south on top, north at the bottom, east on the left, west on the right — the same orientation as a compass plate, and flipped from a modern map. That is the easiest thing to get backwards on day one. Each cell is both a direction and one facet of the matter.
Nine-palace direction diagram (positions only, no chart data)
By tradition the center cell is read as part of the southwest cell. So when you tap the center on this site, everything except “Ground” and “Base” is describing the southwest cell — not a shortcut, but how the Rotating Plate school has always handled it.
Every cell except the center shows three lines and one dot, always in the same places, and each covers something different (the center carries no symbols on the chart itself; tap it and they are listed from the southwest cell, see below).
Where the symbols sit in a cell on the English chart (placeholder labels, not a real chart)
Two more marks: a dashed border means empty — this cell is hollow for now, the matter still up in the air; » means horse — movement, travel, change that comes fast.
The difference between the heaven stem and the earth stem is worth one more sentence. The earth plate is the base, where this matter already stood; the heaven plate is the layer moving right now. Set the tone from the earth plate first, then read the heaven plate for where things are heading — far more useful than hunting for lucky and unlucky patterns straight away.
You are the cell where today's day stem sits on the heaven plate. If you fill in your birth date, the cell of your birth-year stem is read as well.
Every person and every matter has its own significator: a husband is Geng, a wife is Yi, a boss is the Chief, money is the Life Gate, and so on. This step is called picking the significator, and it is the easiest thing to get wrong in the whole reading as well as the most important — pick the wrong one and every sentence afterwards is describing a different matter on the same chart.
After you ask, this site paints the main significator's cell gold and the related ones cyan; tap a gold or cyan cell and it says what that cell stands for in your question. We also publish how often our own pick is right, on the home page: 68.8% by the loose measure, 43.2% by the strict one, both reported side by side (the two are computed over different sets, and the home page says why).
To read two symbols together: pairs in the same palace are the chart's formal combinations, while combinations across palaces are loose association only and cannot be taken as a conclusion from the chart.
This step is not technique, but it decides whether the other four mean anything.
Asking a dozen times a day usually means looking for the answer you already want — and then the one who should stop is the person asking, not the chart.
Hour-based Qimen · Rotating Plate · Chai-bu method, with the day rolling at 23:00: the chart is cast by the double-hour, the Nine Stars and Eight Gates rotate as a whole, and the chart number is set by the solar term and its three periods. Flying Plate, Yin Plate and the year, month and day schools follow different rules, so don't mix them — the same chart read by another school simply doesn't hold.
Both answer the same question: how to carry the chart number across when the leader day and the solar term fall out of step at a term boundary. Chai-bu splits and patches at the nearest leader day; Zhi-run inserts a leap chart number around certain solar terms. This site uses Chai-bu only and offers no toggle — a toggle would mean two incompatible rule sets living in one product.
Clock time in a unified time zone can differ from the actual solar time at your longitude by more than an hour, which is enough to cross a double-hour boundary and swap the whole chart. So the correction has to happen before the chart is cast. This site corrects by your location or by a longitude you type in; with no longitude it will not pretend to have corrected anything — the chart then says plainly that it is clock time.
One thing to watch: the correction moves the clock face only. Which solar term you are in is still judged by the real astronomical moment. Feeding the shifted time into the solar-term calculation gets the chart number wrong around term boundaries — a very common trap in home-made casting tools.
“There is an inauspicious pattern on my chart — is something going to happen?”
A pattern says whether the current runs with this matter right now. It is not a verdict. Qimen Dunjia is part of traditional Chinese culture and its “predictive” function is not science; it should never be used to rule on fortune or on life and death.
“If a cell is empty, is it hopeless?”
Empty means the cell is hollow for now and the matter is still up in the air. It is closer to “not yet” than to “no”.
“I tried another casting app and got a different chart. Why?”
Usually a different school, or a different day-change moment (rolling at 23:00 versus at midnight), and sometimes whether true solar time was corrected at all. Check that both sides follow the same rules before comparing them.
“Can a reading decide for me?”
No. A reading only gives you another angle to think from. It is not medical, financial, legal or psychological advice. For decisions that matter, come back to the real world and talk to a professional.