How to choose a Purple Star calculator

What the implementation can support

Start with reproducibility. A useful Purple Star calculator names its calendar source, explains whether it uses civil or local solar time, states how it treats the late Zi hour and leap months, identifies its transformation table, and lets a reader inspect palace and star positions. “AI-powered” is not a substitute for deterministic placement rules.

Next inspect uncertainty and privacy. The service should not invent a time when it is unknown, should show multiple candidates for a remembered range, and should say what happens to birth data. Public sharing should use a type page with no birth details or scores; a private result should be unindexable, opaque, revocable, and deletable. Analytics events do not need the raw inputs.

Finally compare the commercial boundary. The free output should be complete enough to evaluate before checkout, while a paid layer should show a real sample, price, delivery, refund terms, and limits. PracticeEco publishes this checklist because it also applies here: the tool should be rejected if its live behaviour stops matching these claims.

Use and limits

This page explains a rule, label, or product boundary. It is not a clinical instrument, a forecast, or a substitute for direct evidence about a person. Different Purple Star astrology schools can use different calendar and transformation choices.

Make your free chart and self-assessment

Sources and reproducibility

• Hong Kong Observatory: Gregorian–Lunar Calendar Conversion Table — The calendar-conversion layer used before the chart rules run.
• iztro: open-source Zi Wei Dou Shu implementation — A named, reproducible reference implementation for chart placement.
• iztro documentation: palace and star data structures — The distinction between palaces, major stars, and an opposite palace.
• Standards for Educational and Psychological Testing — The boundary between a reflection exercise and a validated interpretation or use.