Methodology

We believe a charting tool should show its work. This page documents the conventions we follow, where schools disagree, and how we validate results.

1. Calendar and birth time

• Gregorian input is converted to the Chinese lunisolar calendar using a 1900–2100 ephemeris table; leap months and short/long months are checked month by month.
• Birth time to the minute is required, because the hour pillar and the “early/late Zi hour” boundary change the chart.
• True solar time correction is offered as an option: longitude adjustment plus the equation of time. Time zones and daylight-saving rules are applied using the birth location’s historical rules.

2. Palaces and stars

• The 12 palaces are laid out from the Life Palace in the traditional order (Life, Siblings, Spouse, Children, Wealth, Health, Travel, Friends, Career, Property, Fortune, Parents).
• All 14 major stars and the standard auxiliary stars are placed by classical rules; the Five-Element Bureau is derived from the stem-branch of the year and the palace.
• Star brightness (bright / neutral / dim) follows the San He (Three Harmonies) tradition.

3. Four Transformations (Si Hua)

We compute natal, decadal, annual and monthly transformations. Where schools differ on the exact mapping of stems to transformations, we follow the San He convention and record the choice. The “flying star” (self-transformation) layer is displayed separately so you can see which transformation comes from which palace stem.

4. Interpretation

Readings are written in plain language from a fixed library of star-in-palace interpretations, not generated randomly. AI readings (a paid add-on) are produced by a language model from the computed chart structure; they are clearly labelled and are not presented as factual predictions.

5. Validation

• Star placement and brightness are cross-checked against independent open-source implementations (for example iztro and fortel-ziweidoushu) and against classical texts.
• Where two sources disagree, we follow the San He convention and note it here rather than silently picking one.

6. Limitations

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