Reference

Method

Charts disagree for reasons that are knowable. These pages set out the conventions Meridian uses, with worked examples you can check against any other calculator.

Why charts differ 7

The four things that make two calculators disagree, each with a worked example.

Why do two BaZi calculators give you different charts?Four things cause almost every disagreement: true solar time, the day boundary, historical daylight saving, and what happens when the birth time is unknown. A worked example of each. Should a BaZi chart use clock time or true solar time?True solar time, if you want the hour pillar to mean what the tradition intended. Clock time is a modern administrative convenience. The gap reaches over an hour in parts of Asia. Born overseas: which time does your chart use?The time where you were born, corrected to true solar time for that longitude. Not your parents' home time, not Beijing time, and not the time zone you live in now. Does daylight saving change your hour pillar?Yes, when it applied at your birth and the calculator ignores it. One hour of clock error moves the hour pillar by one branch. Hong Kong used summer time until 1979. Does the BaZi day start at 23:00 or at midnight?The 子 hour straddles midnight, so schools disagree on where the day changes. A birth at 23:30 gets a different day pillar depending on the rule. Here is the difference, computed. Can you cast a BaZi chart without a birth time?Yes, for three of the four pillars. The hour pillar cannot be derived without a time, and a calculator that returns one anyway has defaulted to noon without telling you. How does Zi Wei Dou Shu handle a leap month?A leap month is split. Births in the first half count as the month itself, births from the sixteenth day count as the following month. Two weeks apart, a different life palace.
Reading a chart 3

What the parts of a chart mean, and how the eight methods relate to each other.

How Meridian works 3

The conventions, what is computed rather than written, and what a reading will not do.

Method against method 28

What two systems say about the same person, and what actually separates them. Every pairing of the eight methods.

See all 28 pairings

Cast a chart

This page explains calculation conventions. It does not interpret a chart and is not advice.