What is a BaZi chart?
BaZi, or the Four Pillars, is the Chinese way of reading a birth: the year, month, day and hour, each written as a pair of characters, a heavenly stem and an earthly branch. That’s eight characters in all, which is what bazi (八字) means.
Stems, branches and the five elements
There are ten heavenly stems and twelve earthly branches, paired in a cycle of sixty that has counted years, months, days and hours in China for millennia. Each stem and branch carries one of five elements (wood, fire, earth, metal and water) and is either yin or yang. A chart is read by how those eight characters feed, control and clash with each other.
The Day Master is you
The stem of the day pillar stands for the person, and is called the Day Master. The rest of the chart is read in relation to it: what strengthens it, what drains it, what it’s missing. So two people born in the same year and month can read very differently, because their days differ.
Why there are no planets in it
BaZi isn’t a map of the sky the way a Western or Vedic chart is, so there’s no zodiac wheel and no planets in it. It does follow the Sun for its months, though, in that each month begins at one of the solar terms (節), and the year begins at 立春, the start of spring, around 4 February. Not on 1 January, and not on Chinese New Year, which moves between late January and mid-February. So for a birth in those weeks, the BaZi year can differ from the zodiac animal you were told.
The clock question
Practitioners split on two things, which is where most of the disagreement between BaZi apps comes from. Some read the hour from the clock and some from the sun at the birthplace (true solar time), and some turn the day at midnight while others turn it at 23:00, when the first double-hour begins, so each choice can change the hour pillar, and the day one can change the Day Master itself.
We read the clock on standard time, with daylight saving taken off, turn the day at midnight, and always show the solar time beside it. Wherever another convention would give a different pillar, the chart names that one too, so you can follow your own school.
Luck pillars
BaZi also divides a life into ten-year periods called luck pillars (大運). Which way they run depends on the year’s polarity and on a traditional male or female reading, so we ask, and you can decline: the chart is complete without them, and we don’t guess, since a guessed direction runs every decade backwards.
BaZi is also where general AI models struggle most: in our test, the most capable one got all four pillars right for 75% of people, and a smaller one for none. The full test.