The calculation engine
AstroEW uses a published open-source calculation library for Zi Wei Dou Shu, then adds time transparency, three-lens context, and reflective report writing. Zi Wei Dou Shu is one tradition within Chinese and East Asian astrology.
View calculation library and license attribution
AstroEW uses iztro 2.6.1 for the Zi Wei Dou Shu calculation under the MIT License. Copyright (c) 2023 All Contributors. View the full license text.
Three calculation layers
| Layer | Technical source | What the report uses it for |
|---|---|---|
| Western Sun sign | Solar-date sign field | A tropical, seasonal starting point with sign, element, modality, and polarity language. |
| Chinese zodiac year pillar | First year pillar in the traditional calendar output | The animal, earthly branch, heavenly-stem element, and yin-yang polarity returned by the traditional calendar layer. |
| Zi Wei Dou Shu | Twelve-palace chart output | Twelve palaces, Life and Body Palace positions, major stars, supporting stars, transformations, and 10-year cycles. |
These layers are displayed together but are not combined into a score. AstroEW's synthesis is editorial framing around three outputs; it is not a fourth astrological system and it cannot make the underlying traditions scientifically equivalent.
Input and time path
- The visitor enters a Gregorian calendar date, local clock time, a reference city or time zone, and the binary setting required by the current Zi Wei calculation convention.
- AstroEW resolves the civil time with the city's historical time-zone and daylight-saving rules. The original value remains visible in the report.
- Civil time is the default. When the visitor selects approximate true solar time, AstroEW applies longitude relative to the location's standard meridian plus an equation-of-time estimate, then shows the corrected date and time.
- The resulting traditional hour index, gender input, and pinned defaults are passed into the chart calculation so the path can be reproduced.
True-solar time is a convention-sensitive approximation, not a claim of astronomical ephemeris precision. A result near a two-hour traditional boundary should be read with extra care; AstroEW surfaces that warning instead of hiding it.
Pinned defaults
- fixLeap = true: an intercalary lunar month is split according to the library's documented rule.
- yearDivide = normal: the Chinese year follows the first day of the first lunar month; exact solar-term boundaries are a different available setting.
- horoscopeDivide = normal: the library's default monthly boundary.
- dayDivide = forward: late Zi hour is treated as the following day in the default chart calculation.
- algorithm = default: the library's default rule set based on its published data tables.
The open-source library supports other traditions and calculation conventions. Different year boundaries, late-Zi rules, brightness tables, four-transformation tables, or translations can change a chart. When a future release changes the pin or defaults, the version and this page will be updated together.
How the report is written
AstroEW follows a structured report format: a concise overview, technical input summary, three-lens comparison, palace-by-palace context, and a practical reflection prompt. Each palace reading separates the traditional star vocabulary from constructive expression, a question to monitor, opposite-palace context, and a small action.
Astro.com is a reference point for Western astrology users who expect clearly labeled chart sections and interpretive reports. AstroEW currently provides a Western Sun-sign layer, not a full Western natal chart with planets, houses, and aspects.
What a result is not
- It is not a medical diagnosis or treatment plan.
- It is not financial, legal, employment, or relationship advice.
- It is not a guarantee that an event will happen.
- It is not a measure of your worth or ability.
- It is not proof that the three traditions are causally connected.
See the editorial policy, privacy policy, and three-lens framework for the cultural and data context around the calculation.