What a luck pillar is
A natal chart is fixed at birth. Bazi adds a moving layer: a sequence of pillars, each lasting ten years, that the person is said to “walk through”. San Ming Tong Hui uses the image of a series of inns on a journey:
夫运者，人生之传舍。“Luck periods are the post-houses along a person’s life.”— San Ming Tong Hui 《三命通會》, 卷二 · 论大运. Original text: Wikisource · also on ctext.org (different edition). Translation: bazimethod.
Each luck pillar is an ordinary stem-branch pair from the sixty-pair cycle. They are generated from the month pillar by stepping forward or backward through the cycle, one step per ten years. If the month pillar is 丁酉 and the luck runs backward, the luck pillars are 丙申, 乙未, 甲午, 癸巳, 壬辰, and so on.
That example is not hypothetical. The 丁酉 month and backward sequence belong to the chart of the Qianlong Emperor, and Ren Tieqiao’s later commentary on the Di Tian Sui (Di Tian Sui Chan Wei 滴天髓闡微, not the shorter edition we quote) lists his luck pillars beginning 丙申 乙未 — our calculator reproduces the same sequence, and it is one of our automated tests.
Which direction? Forward or backward
The rule combines the polarity of the year stem with gender:
| Yang year stem (甲 丙 戊 庚 壬) | Yin year stem (乙 丁 己 辛 癸) | |
|---|---|---|
| Male | Forward (顺) | Backward (逆) |
| Female | Backward (逆) | Forward (顺) |
San Ming Tong Hui states the rule together with the method for counting the starting age:
阳男阴女，大运以生日后未来节气日时为数，顺而行之；阴男阳女，大运以生日前过去节气日时为数，逆而行之。“For a yang male or yin female, the luck periods are counted by the days and hours from birth forward to the coming solar term, and run forward. For a yin male or yang female, they are counted by the days and hours from birth back to the past solar term, and run backward.”— San Ming Tong Hui 《三命通會》, 卷二 · 论大运. Original text: Wikisource · also on ctext.org (different edition). Translation: bazimethod.
Remember that the year stem is the one of the Bazi year, which begins at 立春, not on 1 January. Someone born on 20 January 2025 has a 甲 (yang) year stem, not 乙.
When does the first luck pillar start?
Count the time from birth to the relevant “jie” solar term — forward to the next one, or backward to the previous one — and convert it with the classical ratio: three days = one year (so one day = four months, and one double-hour = ten days). The text explains where the ratio comes from: three days contain thirty-six double-hours, roughly the 360 days of a schematic year, scaled to the ten years of a luck period.
古人以大运则一辰十岁，折除以三日为年者何？“The ancients took each luck period as ten years, and reckoned three days as one year — why?”— San Ming Tong Hui 《三命通會》, 卷二 · 论大运. Original text: Wikisource · also on ctext.org (different edition). Translation: bazimethod.
It then works an example: a yang male born five days and three double-hours before 立春 starts his luck at one year and nine months.
至二十九日申时正得五日三时之节气，实历过六十三日折除，过六十三时折除，计六百三十日，乃一岁奇九月之大运“Up to the shen hour of the twenty-ninth day is exactly five days and three double-hours to the solar term … reckoned out to 630 days, that is a luck period of one year and nine months.”— San Ming Tong Hui 《三命通會》, 卷二 · 论大运. Original text: Wikisource · also on ctext.org (different edition). Translation: bazimethod.
Our calculator applies the same ratio to the exact minute of the solar term (one minute of time counts as two hours of age), using the open-source lunar-javascript library’s implementation, and displays the result in years, months and days. Because the starting age depends on the distance to a solar term, an error of a couple of hours in the birth time moves the starting age by about ten days — usually unimportant, but worth knowing.
Ages: Chinese counting versus Western
Traditional texts often give ages in xusui (虚岁), where a person is one at birth and gains a year at each new year. Our calculator gives ages in ordinary Western years, alongside the calendar year in which each luck pillar begins, so there is no ambiguity.
How luck pillars are read
A luck pillar is read like a pillar added to the chart: its stem and branch get ten-god labels relative to the Day Master, and practitioners ask whether it supplies what the chart needs (its useful god) or adds to an excess. Classical texts differ on the balance between stem and branch. Yuan Hai Zi Ping stresses the branch:
子平之法，大运看支，岁君看干，交运同接木。“In the Zi Ping method, for the great luck period look at the branch; for the year ruler, look at the stem. Changing luck periods is like grafting a tree.”— Yuan Hai Zi Ping 《淵海子平》, 论大运. Original text: Wikisource · also on ctext.org (different edition). Translation: bazimethod.
San Ming Tong Hui says similar: in the stem part of a luck period, the branch is also used; in the branch part, the stem is set aside — “the great luck period values the earthly branch”. Many modern practitioners instead read the stem as dominant for the first five years and the branch for the last five. The Di Tian Sui puts luck and the individual year together, with the year as even more decisive:
休咎係乎運，尤係乎歲，衝戰視其孰降，和好視其孰切。“Fortune and misfortune depend on the luck period, and even more on the year. In clashes and battles, see which side yields; in harmony and friendship, see which is closer.”— Di Tian Sui (Drops from Heaven’s Marrow) 《滴天髓》, 歲運論. Original text: Wikisource · also on ctext.org (different edition). Translation: bazimethod.
Common questions
Why do my luck pillars differ from another site?
Usually because of the direction rule (check that the year stem was taken from the 立春 year, not the calendar year), the gender setting, or a different month pillar due to time-zone handling near a solar term. Start-age differences of a few months come from rounding conventions.
What about the years before the first luck pillar?
Before the first luck pillar starts, classical texts read the month pillar itself, and some schools use “minor luck” (小运) by the hour pillar. Our calculator shows the main luck pillars only.
Does the gender rule work for everyone?
The rule is part of the classical system and reflects its time. Our calculator asks for gender only to set the direction; you can try both settings to see the difference.
See your luck pillars
The calculator lists eight luck pillars with the age and calendar year each begins, and states the direction and the start-age calculation it used.
Keep learning
Classical quotations are copied from the public-domain texts on Wikisource; links let you check every line. English translations are our own. Traditional Bazi statements are reported as tradition, not as fact.