Bazi Luck Cycle Calculator

What are Da Yun, annual, and monthly cycles?

Check the natal chart and cycle start, choose a major cycle and a year, then read that year’s months. See the luck-cycle reading guide for the full sequence.

Da Yun begins at the first transition instant and usually proceeds in ten-year periods. An annual cycle follows the sexagenary year, changing at Li Chun rather than January 1. A monthly cycle changes at the twelve solar-term “jie,” not on the first day of a Gregorian month. This tool first establishes the natal chart and cycle start, then lists each period with its Gregorian range, annual cycles, and monthly cycles.

The Ten God shown on a cycle is the relationship between that cycle's heavenly stem and the natal Day Stem. Use the Ten Gods lookup table to verify the mapping. It is a structural label, not an automatic verdict about good or bad events. Bazi is presented as a traditional cultural framework for reflection and does not replace medical, legal, investment, or other professional advice.

Which direction and start convention does this site use?

Traditional start rule

The calculator follows the common Zi Ping convention documented in San Ming Tong Hui, Volume 2, “On Major Luck Cycles”. Year-Stem polarity and the traditional sex option determine direction; a forward sequence counts to the following adjacent “jie,” while a reverse sequence counts back to the preceding one. The interval is converted by the traditional rule that three days correspond to one year. Da Yun pillars then proceed forward or backward from the natal Month Pillar.

Yuan Hai Zi Ping is an important source for the Day Master, Ten Gods, and relationships between a chart and its cycles. The specific direction and start conversion here are primarily attributed to San Ming Tong Hui.

Modern civil-time handling

Classical texts state the traditional rule; modern timezone and daylight-saving records help identify the civil instant represented by a birth record. The first-cycle time is displayed in the birthplace’s local civil time. If a recorded wall time falls in a daylight-saving gap or repeated interval, the tool asks for verification instead of guessing.

The IANA Time Zone Database is one major reference for modern civil-time and daylight-saving history. For pre-1970 births or disputed local records, consult the original birth record and additional official historical sources.

When does the current Da Yun change?

The “current” Da Yun changes at the full transition date and time, not prematurely on January 1. If a transition falls mid-year, that Gregorian year touches both adjacent periods; the timeline preserves both positions, while the current marker uses the exact transition instant.

What boundaries do the annual and monthly cycles use?

• The Year Pillar and annual cycle change around the Li Chun solar-term instant, not on January 1 or lunar New Year.
• The Month Pillar and monthly cycles change at the twelve “jie”: Li Chun, Jing Zhe, Qing Ming, Li Xia, Mang Zhong, Xiao Shu, Li Qiu, Bai Lu, Han Lu, Li Dong, Da Xue, and Xiao Han.
• The Day Pillar can use either a 23:00 early-Zi boundary or a midnight boundary. This is an exposed traditional convention, not a claim that one school is scientifically unique.
• With true solar time enabled, longitude and equation-of-time corrections affect local Day and Hour boundaries. Year and Month Pillars still compare the same absolute birth instant with the solar-term instant, so a different clock representation cannot move the birth backward into another solar-term month.

Why can two calculators show different Da Yun results?

Common causes include true-solar handling, a 23:00 versus midnight day boundary, the start-age conversion method, minute-level birth-time uncertainty, missing historical daylight-saving rules, or treating solar-term timestamps as fixed Beijing local times everywhere. Comparing only the first Da Yun pillar is not enough: check the natal pillars, direction, start age, and first-cycle timestamp together.

This page displays those inputs and conventions together. The Bazi calculation method states the conventions used here, while the reproducible validation cases provide fixed inputs and comparison results. Use the true solar time calculator first if the recorded time may sit near a branch or day boundary.

Frequently asked questions

Does the first Da Yun always begin at an exact ten-year age?

No. The first start can include converted years, months, days, and hours, so it often begins at a non-integer age. Later periods then advance in ten-year blocks.

Why does the displayed age differ from Western exact age?

The timeline follows the engine's traditional age sequence and may differ from age calculated strictly from the most recent birthday. Use the listed Gregorian year when identifying calendar time rather than treating the age label as an exact date.

Does true solar time always change the luck cycles?

Generally, it does not directly change Da Yun direction, pillar sequence, or the transition time. True solar time may change the Day or Hour Pillar and the Ten God labels derived from the Day Master; the result identifies whether the correction crossed such a boundary.

Classical basis and time data

• San Ming Tong Hui, “On Major Luck Cycles”: the main classical source for direction, adjacent solar terms, and start-age conversion.
• Yuan Hai Zi Ping: a foundational source for the Four Pillars, Day Master, Ten Gods, and luck-cycle framework.
• Di Tian Sui: a classical reference for stems, branches, seasonal command, and chart relationships.
• IANA Time Zone Database: one major reference for modern civil-time and daylight-saving history; earlier or disputed records still require additional historical sources.

The public tool provides a reviewable timeline and does not claim that a cycle guarantees a specific real-world event. Learn how AI Bazi uses these chart results: it may organize language around the already calculated pillars and cycles, but it may not rewrite the underlying stem-branch data.