BaZi luck pillars: the ten-year cycle

The four pillars describe the chart you were born with. The luck pillars describe when things move: a ten-year pillar for every decade of life, an annual pillar for every year, and a monthly pillar for every solar-term month. Here is how they are built.

Three layers, one idea

A birth chart is fixed. The luck pillars are the moving layer placed over it, and they come in three sizes:

The layers nest: each ten-year pillar contains ten annual pillars, and each annual pillar contains twelve monthly pillars. That is why the calculator lets you click into them one level at a time.

Which way does the cycle run?

This is the one place where two people can share an identical birth chart and still get different luck pillars. The direction is set by pairing the polarity of the birth year stem with gender:

The year stem is yang for Jia, Bing, Wu, Geng and Ren, and yin for Yi, Ding, Ji, Xin and Gui. Two of the four combinations run forward and two run backward, so a chart is never simply “forward for men”.

This is why the calculator asks for gender at all. It does not enter the four pillars — it only fixes the direction, and therefore the first pillar and every pillar after it.

Where the first pillar comes from

Take the month pillar of the birth chart and step it one place along the sixty-pillar cycle, in the direction you just worked out. That single step is the first ten-year pillar. Every pillar after it is another decade further along the same path. The cycle runs unbroken, which is a useful check: if two neighbouring pillars in a chart are not adjacent in the sexagenary cycle, something is wrong.

When the first decade opens

The start age is not the birth date and it is not a fixed number of years. It is the distance from the birth moment to the neighbouring jie solar term — the terms that open a month, such as Start of Spring and Awakening of Insects — converted at a rate of three days to one year. In the same conversion, one day counts as four months and one two-hour watch as ten days.

The consequence is larger than most people expect. A child born a few days before the term and a child born a few days after it open their first decade years apart, even on the same day of the same year. And because the term is measured in true solar time, the corrections on the true solar time page feed into this number too.

A worked example

Take a birth on 1 June 1988 at 12:00 in Beijing. Corrected to true solar time that is 10:48, and the four pillars are 戊辰 丁巳 丁亥 乙巳. The year stem, 戊 (Wu), is yang.

Same moment, same place, same four pillars, and the two readings open on completely different pillars at completely different ages. For the male, the decade covering 2019 to 2028 — ages 32 to 41 — is carried by 辛酉, with the annual pillars running 己亥 in 2019 up to 戊申 in 2028.

Reading the annual and monthly pillars

The annual pillar is simply the pillar of that calendar year in the sixty-pillar cycle: 2024 is 甲辰 and 2025 is 乙巳. Inside a year, the monthly pillars switch at the solar terms rather than at the first of the month, and the sequence of stems depends on the year stem — a Jia or Ji year opens its first month on 丙寅, which is the rule remembered as “Jia and Ji years begin with Bing”.

These layers are traditionally read against the birth chart rather than on their own, and schools differ on how much weight each deserves. Read them as a way of talking about timing, alongside a qualified reader rather than instead of one.