Casting method
Yarrow-Weighted Digital Cast
The traditional yarrow-stalk ritual sorts fifty stalks into groups three times to produce each line. It does not give every line value the same chance. The digital cast reproduces those odds without the ritual: each line is drawn from sixteen equally likely outcomes, mapped to the four line values.
| Value | Line | Fraction | Chance |
|---|---|---|---|
| 6 | Old yin (changing) | 1/16 | 6.25% |
| 7 | Young yang (stable) | 5/16 | 31.25% |
| 8 | Young yin (stable) | 7/16 | 43.75% |
| 9 | Old yang (changing) | 3/16 | 18.75% |
Random numbers come from the browser cryptography API, with rejection sampling so no outcome is favored. Six lines are drawn from the bottom upward, then the primary hexagram, any changing lines and the relating hexagram are worked out.
What the odds mean
- A line is changing 25% of the time (old yin 1/16 plus old yang 3/16).
- Old yang is three times as likely as old yin, which is the known asymmetry of the yarrow method.
- The chance that a six-line cast has no changing lines at all is 17.8%.
- Every one of the 64 primary hexagrams is equally likely (1/64), because yang and yin lines are each 50% likely.
| Changing lines in a cast | Chance |
|---|---|
| 0 | 17.8% |
| 1 | 35.6% |
| 2 | 29.66% |
| 3 | 13.18% |
| 4 | 3.3% |
| 5 | 0.44% |
| 6 | 0.02% |
Reading the result
- Find the primary hexagram from the six lines.
- If no line is changing, read that hexagram on its own.
- If lines are changing, read the line text for each changing line.
- Change those lines to their opposite to find the relating hexagram, the direction the situation is moving.
Compare with the other method or look up any figure in the library.
Cite this page
The Free I Ching. "Yarrow-Weighted Digital Cast." https://thefreeiching.com/methods/yarrow (updated 2026-10-07).
The I Ching is a tool for reflection, not a prediction. Nothing here forecasts events or replaces professional advice. Short quotations with a link back are welcome. Please do not republish a page in full. The open data files at /data are licensed CC BY 4.0.
Updated October 7, 2026. Markdown version