Zi Wei Dou Shu (紫微斗數), often translated as Purple Star Astrology, is a classical Chinese astrological system that produces a detailed life chart from your date and time of birth. It organizes your life into twelve palaces — Self, Marriage, Career, Wealth, Health, and so on — and places fourteen major stars plus dozens of minor stars across them. For a proper introduction see our primer.
No. The Chinese zodiac animal is only the Earthly Branch of your birth year — one-quarter of a BaZi chart and less of a Zi Wei chart. Reading a whole personality from a zodiac animal is like reading a Western chart from only the sun sign. Zi Wei uses the full birth date, time, and two-hour block, and produces a chart with far more structure than a zodiac animal can carry.
BaZi and Zi Wei use the same birth inputs but build very different instruments. BaZi reads the chart through the Five Elements; Zi Wei reads it through twelve named life domains. They're complementary, not interchangeable. Our comparison post covers this in detail.
Zi Wei Dou Shu is a thousand-year-old interpretive tradition, not an empirically validated predictive science. A well-produced chart can be a useful lens for self-reflection and for understanding patterns in a life, but it should not be used to make medical, financial, or legal decisions. Our Terms of Service make this explicit: astrological interpretations are for entertainment and educational purposes.
Zi Wei uses the two-hour shichen block of your birth to position the Ming palace (the palace of the self). An error of a few minutes almost never matters, but an error that crosses a two-hour boundary (for example, 10:55 PM vs. 11:05 PM) can move the entire chart into a different configuration. The most consequential boundary is 11:00 PM — births at or after 23:00 advance the lunar day by traditional rule.
A few strategies:
We're planning a birth-time rectification tool as a future feature.
Use your local time with the time zone of your birth location. Our calculator takes these two inputs and computes the position of the sky at your birth, which is what Zi Wei actually reads. Some traditional practitioners convert every chart to Beijing time (UTC+8) as a standard reference, which will produce a different chart for anyone born outside China. If a practitioner's chart disagrees with ours, this is usually why. See our full post on local vs. Beijing time for the details and how to convert between the two.
Traditional Chinese timekeeping divides the day into twelve two-hour shichen blocks, and the first block — Zi (子) — begins at 23:00, not at midnight. Births at or after 23:00 fall into the Zi hour of the following lunar day. This is a traditional rule, not a clock-time artifact; for charting purposes it means someone born at 22:45 and someone born at 23:15 on the same solar date can have different lunar dates, different stem-branch pillars, and significantly different charts.
Yes — enter the time that was shown on the clock at your birth, and pick the time zone that was in effect on that date. If your birth location observed DST and the clock was advanced one hour, the local time you enter should reflect that. The calculator does not apply DST corrections automatically; you give it the actual clock time and the actual zone, and it reads the sky from there.
There are three common reasons:
We use the month-stem method following Kwok Man Ho and Martin Palmer's The Complete Book of Chinese Horoscopes (Sunburst Books, 1995, pp. 294–295), which aligns with the Zhongzhou (中州派) school for the three disputed stems. Details and comparison table on our methodology page and in the Si Hua post.
Brightness (廟旺陷) tables follow the San He (三合派) classical tradition, cross-referenced from two independent open-source implementations: iztro (3,600+ GitHub stars) and fortel-ziweidoushu. Where schools disagree on a specific rating, we pick the San He convention and document it on the methodology page.
Mobile app store prices may differ slightly because Apple takes a 15–30% cut; on iOS our Basic is $5.99 and Pro is $24.99 to keep net revenue comparable.
No. Every paid tier is a one-time purchase. You pay once, you own the access.
Email support@ziweicharts.com within 14 days of purchase and we'll process a refund through Stripe, no questions asked. Full terms in our Terms of Service.
Use the "Already paid?" link at the paywall on any device, enter the email address you used for checkout, and the tier will restore automatically. The same mechanism works on the web, the desktop app, and (when available) the mobile apps. If it doesn't find your purchase, email support@ziweicharts.com with the approximate purchase date and we'll sort it out.
Your birth data stays on your device. We use localStorage to save profiles you explicitly save via the "Save Profile" button; this data never leaves your browser. We do not have accounts, we do not have a server-side database of charts, and we do not sell data to anyone. Payment email addresses are retained by Stripe (for the purchase record and restore functionality) and by us only to the extent Stripe returns them on verify-session. Full detail on our Privacy Policy.
English, Traditional Chinese (繁體中文), and Simplified Chinese (简体中文). Each language has the full 187-interpretation library and the complete UI. Auto-detects browser language on first visit; you can switch at any time with the buttons in the top-right.
A Windows and macOS desktop app is available via GitHub releases. iOS and Android apps are planned for the next few weeks — see our TODO if you want the latest status. The web app at ziweicharts.com is fully responsive and works well on mobile browsers in the meantime.
The web app is a Progressive Web App — you can "Install" it to your device from your browser and it'll work offline once cached. The desktop apps (Windows, Mac) are always offline. Payment flow requires an internet connection because Stripe's payment form is hosted on Stripe's servers.
Email support@ziweicharts.com or open an issue on GitHub. Bug reports that include your birth date (for reproducing) and a screenshot are the easiest to investigate. We take Si Hua disagreements and brightness-rating corrections especially seriously, because those are where schools actually differ — if you think we have something wrong, send the source you're citing and we'll look carefully.
Questions we didn't answer? Email support@ziweicharts.com — we read every message. For the methodology details behind how the chart is calculated, see the methodology page. For deeper reading on the system, the blog has primers on Zi Wei Dou Shu, the Ming palace, and the Si Hua debate.