What is BaZi?
The Four Pillars explained

Why are there four pillars and eight characters?

The Year, Month, Day and Hour Pillars each contain one Heavenly Stem above one Earthly Branch. The Year Pillar frames ancestry and the wider environment; the Month Pillar carries the season and social setting; the Day Pillar contains the chart’s reference point; and the Hour Pillar is often connected with expression, outcomes and later development. These associations are starting positions, not four sealed boxes.

Stems

Ten visible symbols, each assigned yin or yang and Wood, Fire, Earth, Metal or Water.

Branches

Twelve seasonal symbols that also contain one or more hidden stems.

Day Master

The stem of the Day Pillar. Every other character is classified by its relationship to it.

The solar terms matter more than the calendar label

A BaZi year usually changes around the Beginning of Spring, not automatically on January 1 or Lunar New Year. Months change at the entry points of the 12 major solar terms. A person born close to one of these boundaries needs an exact birth time and location; a date alone may place the Month or Year Pillar on the wrong side of the boundary.

How the Five Elements are actually judged

Counting Wood, Fire, Earth, Metal and Water is only the first glance. Season changes their strength. A stem may be rooted in a branch, supported by another element, drained by what it produces, or controlled by what overcomes it. Combinations and clashes can redirect the pattern. Therefore “you have no Water, so you need Water” is not a complete BaZi judgment.

What are the Ten Gods?

The Ten Gods translate elemental relationships into functions. Companion relates to the same element as the Day Master; Output is produced by it; Wealth is controlled by it; Power controls it; and Resource produces it. Each group splits into a yin/yang pair, creating ten labels. They can describe ways of competing, expressing, managing resources, meeting responsibility and learning. They are relationships in a chart, not ten fixed personality types.

Original chart, Luck Pillars and annual cycles

The birth chart is the natal structure. Luck Pillars introduce successive long phases, commonly described as ten-year periods, while annual pillars add the year’s immediate condition. A new cycle does not erase the birth chart. It activates, supports or pressures relationships already present. Two people meeting the same annual stem and branch can experience different themes because their Day Masters, natal structures and current Luck Pillars differ.

A small worked example

Suppose the Day Master is Yang Wood (Jia) and another visible stem is Yang Metal (Geng). Metal controls Wood, and both share yang polarity. In Ten Gods language, Geng is Seven Killings—often translated as Indirect Officer—for this Day Master. That statement identifies one relationship only. To interpret it, a reader still asks whether Wood has seasonal support and roots, whether Metal is strong, and whether Resource or Output mediates the pressure.

A reliable beginner reading order

1. Verify calendar conversion, solar-term boundaries and the four pillars.
2. Identify the Day Master and the Month Branch’s season.
3. Check roots, support, drainage and control across the whole chart.
4. Map Ten Gods only after those elemental relationships are clear.
5. Add combinations, clashes and hidden stems.
6. Then compare the natal structure with Luck Pillars and annual cycles.

Where schools differ

Major lineages share the Four Pillars, Day Master and Five Element framework, yet may differ on the midnight boundary, true solar-time correction, the precise age a Luck Pillar begins, and whether seasonal regulation, structural pattern or strength balancing comes first. When two readings disagree, first check whether they calculated the same pillars before comparing interpretation.