User Guide

Every feature on this site deliberately lays out the calculation itself, because agreeing on the conclusion is not the same as agreeing on the method — two sites can hand you the same Four Pillars when one applied true solar time and the other did not, and the two errors happened to cancel out.

Bazi Chart Calculation

How to enter your birth time

Enter the time exactly as printed on your birth certificate. Do not convert it yourself.

This is the single most common source of error, and it matters especially to anyone born in mainland China between 1986 and 1991: Daylight Saving Time was in effect in those years, so the time on the certificate has already been put forward by an hour. Many people have heard about this, subtract the hour themselves — and the system then subtracts it a second time, throwing the Hour Pillar off entirely.

The system works out whether DST was in effect from your birthplace and birth date and strips it for you. Every step of the conversion is listed under "Conversion Steps" on the result page, so you can check it line by line.

Birthplace is not an optional field

Birthplace determines three things: the time zone, whether DST was in effect there at the time, and the longitude correction for true solar time. Without it, the first two cannot be established at all.

True solar time correction

Uses the longitude of your birthplace and the equation of time to shift the clock so that solar noon falls exactly at the midpoint of the Wu (Horse) hour.

This site does not enable it by default. That is not laziness: schools genuinely disagree about whether true solar time should be used, and picking a default for you would mean picking a school for you. Tick the box if you want it.

Worth adding: a longitude correction on its own is not enough — the equation of time swings between roughly plus and minus sixteen minutes across the year. True solar time means both, and this site calculates both.

Which day the Zi hour belongs to

Schools differ on whether the stretch from 23:00 to midnight (Late Zi) counts as today or as tomorrow:

• Late Zi belongs to the current day (the common practice, and this site's default)
• Late Zi belongs to the next day

Changing this option changes both the Day Pillar and the Hour Pillar. The same birth moment under two different settings is two different charts, and saved charts and history record them separately.

One thing that is easy to misread

The Year and Month Pillars turn on solar terms, against a UTC+8 reference frame; the Day and Hour Pillars follow local wall-clock time (the Zi hour begins at local midnight).

So one person's Year and Month Pillars are not measured with the same ruler as their Day and Hour Pillars. That is the traditional method, not a choice this site made.

Also: a leap month does not affect the Month Pillar. The Month Pillar turns on a solar term, never on any lunar month boundary.

Traditional/Simplified Confusables

What this section collects is the one-simplified-to-multiple-traditional case: one simplified character corresponds to several traditional ones, and choosing the wrong one is simply writing the wrong character.

For example, 发 has two traditional counterparts, one used for hair (髮) and one for happening or issuing forth (發); 后 has two, one for an empress (后) and one for behind or after (後); 面 has two, one for noodles (麵) and one for a face (面). Each belongs in different words, and using the wrong one is an error.

For the complete list and a character-by-character comparison, see Traditional/Simplified Confusables. The data on that page never passes through automatic conversion, so whichever edition of the site you are reading, both forms appear exactly as written.

Every usage judgment there carries a dictionary source and a link to the entry. Entries without a source are marked "unverified" — we do not pretend they have been checked.

Cross-Strait Naming Differences

These are not wrong characters. The two sides simply say it differently, and both are correct.

質量 (Mainland) / 品質 (Taiwan)　程序 (Mainland) / 程式 (Taiwan)

They sit on a separate tab from the confusables because mixing the two would send the wrong message — as though writing 質量 were a mistake. It is not.

⚠️ This category is particularly easy to misjudge, because the same word does not always need swapping. 質量 differs across the strait when it means quality, but is the same on both sides when it means mass in physics. 程序 differs when it means a computer program, but is the same when it means a legal or administrative procedure.

Simplified-to-Traditional Risk Detection

Paste in a passage of simplified text and it will mark the characters that have more than one traditional candidate and could convert incorrectly.

It does not convert for you. The correct answer depends on context, and context takes a human to judge — a tool that claims to convert correctly on its own will not tell you when it is wrong, and that is more dangerous than not converting at all.

Its job is to tell you where to be careful first. The rest is your call.