How BaZi Luck Pillars Work: Why Some People Start at Age 3 and Others at Age 8

Last updated: October 22, 2026

In a Four Pillars (BaZi) chart, the natal chart captures the four pillars of the birth moment, Luck Pillars (Da Yun) represent ten-year timing cycles stepped forward or backward from the Month Pillar, and annual cycles (Liu Nian) represent the stem–branch pair of each passing calendar year.¹

Why does one person's first Luck Pillar begin around age 2 while another's begins around age 8? Traditional BaZi determines Luck Pillars in two steps: first, the Yin/Yang polarity of the Year Stem combined with sex determines whether the pillars progress forward or in reverse; second, the time interval between the birth moment and the relevant Solar Term (Jie) is converted using the classical rule 3 days = 1 year, 1 day = 4 months, and 1 two-hour branch (shichen) = 10 days.¹

Step 1: Forward vs. Reverse Progression (Year Stem Polarity × Sex)

Every Luck Pillar sequence starts from the natal Month Pillar and moves along the 60 stem–branch (Jia-Zi) cycle. Whether it moves forward or backward (in reverse) depends on the Heavenly Stem of the Year Pillar (not the Day Master) and the subject's sex:¹²

Five Yang Year Stems: Jia (甲), Bing (丙), Wu (戊), Geng (庚), Ren (壬)
Five Yin Year Stems: Yi (乙), Ding (丁), Ji (己), Xin (辛), Gui (癸)

Birth Year Heavenly Stem	Male (Qian) Progression	Female (Kun) Progression	Which Solar Term (Jie) Do You Count Toward?
Yang Year Stem (Jia, Bing, Wu, Geng, Ren)	Forward	Reverse	Forward: Count forward from the birth moment to the *next upcoming Jie* solar term Reverse: Count backward from the birth moment to the most recently passed Jie solar term**
Yin Year Stem (Yi, Ding, Ji, Xin, Gui)	Reverse	Forward	Reverse: Count backward from the birth moment to the *most recently passed Jie* solar term Forward: Count forward from the birth moment to the next upcoming Jie solar term**

(Note: Only the twelve month-changing Jie solar terms—such as 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—are used for Month Pillar transitions and Luck Pillar counting; mid-month Qi terms like the equinoxes and solstices are not used. For births occurring on the exact day of a solar term transition, see Born on a Solar Term Day: Reverse Luck Pillar Counting.)

Step 2: The Classical "3 Days = 1 Year" Conversion Table

Once the interval between the birth moment and the target Jie solar term is measured in days and hours, classical texts such as San Ming Tong Hui convert that interval into the starting age of the first Luck Pillar using three proportions (derived from a 30-day solar month representing a 10-year Luck Pillar):¹

3 days = 1 year
1 day (24 hours) = 4 months (so 6 hours = 1 month)
1 two-hour branch (shichen, 2 hours) = 10 days (so 1 hour = 5 days)

Distance Between Birth Moment and Target Jie Solar Term	Classical Conversion (3 Days = 1 Year, 1 Day = 4 Months, 2 Hours = 10 Days)	Approximate Starting Age of First Luck Pillar
1 day, 6 hours (1 day + 3 shichen)	4 months + 30 days ≈ ~5 months after birth	Starts within Age 0–1 (first year of life)
3 days	1 year	Starts around Age 1
6 days	2 years	Starts around Age 2
9 days	3 years	Starts around Age 3
15 days	5 years	Starts around Age 5
17 days, 2 hours (17 days + 1 shichen)	15 days (5 yr) + 2 days (8 mo) + 2 hours (10 days) = 5 years, 8 months, 10 days	Starts around 5 years, 8 months after birth (see worked example below)
24 days	8 years	Starts around Age 8
30 days	10 years	Starts around Age 10

Step 3: Complete Worked Example (From Birth Date to Handover Year)

Let's walk through the exact calculation using the fictional sample chart "Mr. Chen" from Xiaodao's public Sample Bazi Report and BaZi Calculator (a fictional birth record used solely to illustrate chart structure):³

Fictional Birth Input: Male (Qian), born July 21, 1984 at 14:10 local clock time in Nanjing, China (local True Solar Time is 13:58).
Four Natal Pillars: Year Pillar Jia-Zi (甲子), Month Pillar Xin-Wei (辛未), Day Pillar Bing-Chen (丙辰, Bing Fire Day Master), Hour Pillar Yi-Wei (乙未).
1. Direction and Luck Pillar Sequence:
The Year Stem is Jia (甲, Yang Wood). Because this is a Yang-year Male chart, the Luck Pillars progress forward.
Stepping forward from the Month Pillar Xin-Wei (辛未) along the 60-pillar cycle gives the ten-year Luck Pillars: 1st Ren-Shen (壬申), 2nd Gui-You (癸酉), 3rd Jia-Xu (甲戌), 4th Yi-Hai (乙亥), 5th Bing-Zi (丙子), 6th Ding-Chou (丁丑), and so on.
2. Interval to the Next Jie Solar Term:
July 21, 1984 falls in the Wei month (between Xiao Shu on 1984-07-07 06:29 and Li Qiu on 1984-08-07 16:17, UTC+8).
Counting forward from 1984-07-21 14:10 to Li Qiu at 1984-08-07 16:17 gives an interval of 17 days, 2 hours, and 7 minutes (17 days and roughly 1 shichen).
3. Classical Starting Age and Handover Year:
15 days ÷ 3 = 5 years;
Remaining 2 days × 4 months = 8 months;
Remaining ~2 hours (1 shichen) = 10 days (totaling 5 years, 8 months, and 10+ days after birth).
Adding 5 years, 8 months, and 10 days to July 1984 places the Luck Pillar handover in April 1990. Accordingly, the chart enters its 1st Luck Pillar Ren-Shen in 1990–1999, 2nd Gui-You in 2000–2009, 3rd Jia-Xu in 2010–2019, and 4th Yi-Hai in 2020–2029 (so both 2026 Bing-Wu and 2027 Ding-Wei fall inside the Yi-Hai Luck Pillar).

General-purpose chat models that calculate BaZi without an astronomical solar-term table often approximate the solar-term date or round the starting age crudely, shifting the Luck Pillar handover year by a year or more; we recommend verifying Luck Pillar start years with a calculator that applies full calendar rules.

How to Explore Your Luck Pillars and Annual Timeline on Xiaodao

Interactive Timeline on the Free Chart Page: In Cast a Bazi chart, guests can preview the four natal pillars and chart header; viewing Luck Pillars, annual cycles (liu nian), monthly cycles (liu yue), and the interactive Timeline requires registering and saving a profile. Once saved, the chart page displays the forward/reverse direction, the exact years-months-days until the first Luck Pillar, and an interactive Timeline where you can click through ten-year Luck Pillars, passing years (liu nian), solar-term months (liu yue), and optional daily pillars (liu ri).
11-Chapter Bazi Report: For profiles with complete birth details, Xiaodao's written Bazi Report (which requires Xuan-tier Daoyou or above and uses Dao Points; see Membership & Dao Points for pricing) includes Chapter 1 (Life Timeline), Chapter 4 (Recent Years), Chapter 5 (Luck Pillars), and Chapter 10 (This Year and the Next Six). You can read the complete fictional sample reports for Mr. Chen and Ms. Lin for free on the Sample Bazi Report page.³

Frequently Asked Questions

Is forward or reverse Luck Pillar progression based on the Day Master or the Year Stem?

It is based on the Heavenly Stem of the Year Pillar combined with sex, never the Day Master. In the sample chart above, the Day Master is Bing Fire, but the forward progression comes from the Jia (Yang Wood) Year Stem and male sex.¹

Why do two BaZi websites sometimes show a 1-year difference in the starting age number?

What governs the chart during early childhood before the first Luck Pillar begins?

Cast a Chart and Explore the Interactive Luck Pillars Timeline

In Xiaodao's free BaZi Calculator, guests can preview the four natal pillars and chart header; sign up and save a profile to view the ten-year Luck Pillars, annual, and monthly Timeline, and receive 200 Dao Points credited immediately upon first registration. Or read Chapter 5 (Luck Pillars) in our free Sample Bazi Report.

Cast a Bazi chart Sample report

Sources

1
Wan Minying, San Ming Tong Hui, volume 2, “论天干阴阳生死,” “论大运,” and “总论岁运.” Classical rules for stem polarity, forward/reverse Luck Pillar progression, and the 3-days-per-year starting age calculation.
2
Hong Kong Observatory, Solar Terms, checked October 22, 2026. Solar term calendar structure.
3
Xiaodao, public Bazi Report guide (https://xiaodaox.com/en/guide/bazi-report) and Sample Report (https://xiaodaox.com/en/guide/bazi-report/sample), checked October 22, 2026.