How to cast the I Ching
6 min read · XUANJI
Before you throw anything
An I Ching reading starts with a question, not a coin. The classical texts are unusually blunt about this: an unfocused question produces an unreadable answer. Narrow what you are asking until it has a direction. "Should I take the job in Hangzhou?" is answerable. "What does my future hold?" is not — there is nothing to check the answer against.
Write the question down. The act of writing forces you to commit to one version of it, and you will want it in front of you when the hexagram gets difficult to read.
The three-coin method
You need three identical coins. Chinese cash coins with a square hole are traditional, but the method does not care what the coins are — any three coins with two distinguishable faces work.
For each toss, throw all three at once and count the tails:
- 0 tails (three heads) → old yin, a changing yin line. Written as ✕
- 1 tail → young yang, a stable yang line. Written as ─
- 2 tails → young yin, a stable yin line. Written as ─ ─
- 3 tails → old yang, a changing yang line. Written as ○
That is the whole mechanic. Six tosses, six lines.
(One common convention counts heads instead, and calls three heads "old yang". The naming flips; the mathematics does not. What matters is that one result is rare — 1 in 8 — and produces a changing line. Pick a convention and stay with it, or your reading will drift.)
Build from the bottom up
The first toss is the bottom line, the sixth toss is the top line. This is the single most common beginner error: people draw the hexagram top-down because they toss top-down, and end up reading the wrong figure entirely.
Draw as you go. Six lines, numbered 1 at the bottom to 6 at the top, before you look anything up.
What a changing line actually does
A stable line stays exactly as cast. A changing line flips into its opposite once the reading is complete — yang becomes yin, yin becomes yang.
That flip creates a second hexagram. The figure you cast is the primary hexagram (本卦, ben gua): the situation as it stands. The figure after all the flips is the transformed hexagram (变卦, bian gua): the direction the situation moves toward.
If no line changes — all six stable — you have a static hexagram. Nothing is moving; read the primary hexagram alone and take it as a description of a settled state.
An example, end to end
Six tosses, recorded bottom-up:
line 6: 1 tail ——— young yang
line 5: 0 tails — ✕ — old yin (changing)
line 4: 2 tails —— —— young yin
line 3: 3 tails ——O—— old yang (changing)
line 2: 1 tail ——— young yang
line 1: 2 tails —— —— young yin
Reading bottom to top the primary hexagram is ䷧ Hexagram 40, Deliverance (解). Lines 3 and 5 are changing, so both flip: line 3 becomes yin, line 5 becomes yang. Read the resulting figure bottom to top and you get ䷟ Hexagram 32, Duration (恒).
So: the situation is Deliverance — tension breaking, the knot loosening. It moves toward Duration — what comes out of the release is something that lasts. Two changing lines, so both line texts are read, and by the classical weighting the upper changing line carries more.
That is a complete reading. No cards, no spread, no account.
Recording it properly
Write down three things: the six lines in order with their change markers, the primary hexagram number, the transformed hexagram number. Without the line-by-line record you cannot check a reading later, and the changing lines — which carry most of the specific information — are exactly what gets lost from memory.
Photograph the drawing on your phone if it is easier. Just keep the raw data.
Frequently asked
Can I cast online instead of using coins?
Yes, and the mathematics are identical. A coin toss is 50/50 per coin; a good random source gives the same four outcomes at the same probabilities — 3/8 young yang, 3/8 young yin, 1/8 old yang, 1/8 old yin. What does not work is casting on a whim, repeatedly, until the answer suits you.
How many questions can I ask?
One hexagram per question. The classical texts are explicit that repeating a question to get a better answer invalidates the practice. Ask once, sit with the answer even if you dislike it, and come back to it days later.
What if all six lines are changing?
Rare — 1 in 4096. Read the primary and transformed hexagrams, and by most traditions use the top line text, with the classical caveat that when all lines change the reading shifts to the transformed hexagram as the primary message.