This BaZi calculator turns your date, time and place of birth into the eight characters of a Four Pillars chart (八字, bā zì, literally “eight characters”) and lays them out pillar by pillar. Reading a chart comes next, but first the characters have to be right. Below: what the calculator shows, where each number comes from, and the mistakes people make most often when they work a chart out by hand or on a random website.

1 What the calculator shows

A BaZi chart has four pillars: the year, month, day and hour of birth. Each pillar holds two characters — a heavenly stem 天干 (tiān gān) on top and an earthly branch 地支 (dì zhī) below. There are ten stems and twelve branches, and every character has an element and a Yin or Yang polarity. After the calculation you will see:

Every block comes with a short note: what kind of Day Master you have, which elements dominate and what that means for your chart, which god rules your current luck pillar. The notes follow the classical Zi Ping (子平) school and are deliberately brief. A connected, written account of the whole chart is a reading rather than a calculator — more on that at the end of the page.

2 What you need to enter

Date of birth — the ordinary Gregorian date. There is no need to convert it to the lunar calendar: the pillars follow the solar seasons, and the lunar date plays no part in the calculation at all.

Time of birth — local clock time where you were born, as written on your birth certificate or hospital record. Do not convert it to another time zone and do not remove daylight saving yourself: the calculator knows which time was in force in that city on that day and applies the correction once. If you do not know the time, leave the field empty. You will get a three-pillar chart without the hour, which is more honest than typing in noon: an invented hour gives an invented pillar and invented conclusions. The article on exact birth time explains how to track it down.

Place of birth — choose the city from the suggestions, where region and country are shown. The calculator takes the time zone history and the longitude from it. Cities with the same name are more common than you might think: London, Ontario and London, England are five hours apart.

Sex only affects the direction of the luck pillars. The pillars themselves do not depend on it.

The calculator asks for nothing but your birth data: no email, no account. Your chart is saved in this browser, so your account page and the checkout can pick it up later without retyping.

3 How the chart is calculated

Year. The BaZi year does not start on 1 January or at Chinese New Year. It starts at the solar term 立春 (lì chūn, “start of spring”), which falls on 3–5 February. Someone born on 1 February 1990 is a Horse by the calendar year and even by Chinese New Year (27 January 1990), but 立春 came on 4 February that year, so the year pillar of the chart is 己巳, the Earth Snake. Chinese New Year follows the Moon and moves between 21 January and 20 February, which is why it is not used for the chart.

Month. The twelve months of the chart are solar. Each begins at one of twelve 節 (jié) solar terms and runs to the next: the Tiger month 寅 opens at the same 立春, the Rabbit month 卯 around 6 March, and so on. That is why people born on 5 March and on 7 March usually get different month pillars. The month pillar describes the season of birth, and the season decides how strong the Day Master is.

Day. Day pillars run in an unbroken sixty-day cycle, independent of months. This is where the Day Master comes from. The day in the chart starts at midnight by true solar time, not by the clock.

Hour. The day is divided into twelve two-hour blocks by branch: the Rat hour 子 from 23:00 to 01:00, the Ox hour 丑 from 01:00 to 03:00, and around the circle. The hour stem is derived from the day stem with a fixed table, so the hour cannot be calculated without the day pillar. All boundaries are taken by the sun at the place of birth.

Luck pillars. The first luck pillar grows out of the month pillar, and the rest follow the sixty-pillar cycle forwards or backwards. Men born in a Yang year and women born in a Yin year move forwards; everyone else moves backwards. The age at which the first pillar starts is found from the distance between birth and the nearest solar term in that direction: three days equal one year. That is why starting ages look like “3.2 years” — exactly as they should.

The Moon does not enter the calculation at any step. If a website asks you to choose a “lunar or solar date”, that is only an input format: a correct calculator converts the date to solar anyway.

4 Birth hour accuracy and true solar time

Clocks show zone time. The sun in a given city keeps its own time: at solar noon it stands at its highest point, and that moment rarely matches 12:00 on the clock. The difference has three parts.

  1. Longitude. Every degree east or west of the zone’s central meridian shifts solar time by four minutes. New York sits at 74° west, so its solar time is UTC−4:56: close to Eastern Standard Time, but almost an hour behind summer clocks.
  2. Daylight saving and wartime clocks. Summer time adds another hour. History adds more: the United States kept year-round “War Time” from 1942 to 1945 and daylight time through the winter of 1974; Britain ran Double Summer Time during the Second World War and stayed on summer time all year from 1968 to 1971. The same “12:30” means a different position of the sun in different years.
  3. The equation of time. Earth moves unevenly along its orbit, so through the year the sun runs up to 16 minutes ahead of or behind average clock time.

A worked example. New York, 15 May 1990, 12:30 on the clock. In May 1990 New York was on Eastern Daylight Time, UTC−4. Solar time at New York’s longitude is about UTC−4:56, and in mid-May the sun runs about four minutes fast. Result: 11:37 true solar time, a correction of −52 minutes. The Horse hour 午 (11:00–13:00) holds. But a birth at 11:30 on the clock would be 10:37 by the sun — already the Snake hour 巳 — and the hour pillar would be 辛巳 instead of 壬午.

The calculator applies this correction itself and shows it under the pillar table. If your birth time lies within half an hour of an hour boundary, treat the hour pillar with care and check it against your life. Methods for settling a doubtful hour are covered in the article on birth-time rectification.

The Rat hour and the day boundary. Births between 23:00 and 01:00 are the most disputed case: schools disagree on when to switch the day pillar. In this calculator the day changes at midnight by the sun, while after 23:00 the hour stem is already taken from the next day (the “late Rat hour”, 晚子時). If you were born in that window and another site shows a different day pillar, this rule is almost certainly the reason.

5 Common mistakes

6 How to read the result

Start with the Day Master: in the language of the chart it is you, and every other character is described in relation to it. Then look at the month pillar — the season of birth hints at whether the Day Master is strong or weak. Then the element balance: which elements support the Day Master, which press on it, which it spends. The Ten Gods translate that balance into life themes — work, money, relationships, learning. The luck pillars show what background each decade adds.

The step-by-step order is in How to Read a BaZi Chart. If you are new to the system, begin with the beginner’s guide and What the Day Master Is, and for the decades, read the luck pillars guide.

The calculator answers “which characters are in my chart”. “What does it mean for me” is answered by reading the chart as a whole, and element percentages are no substitute for that.

7 Why different calculators give different charts

With the same data and a correct calculation, the eight characters match on any website, in any country and in any language. Korean saju, Japanese shichū suimei and Chinese BaZi all compute the same chart. Differences come from four places: whether true solar time is used, where the year boundary is drawn, how the Rat hour is handled, and whether the site knows the time zone history of your city. If you have two different charts, check these points one by one — the answer is in one of them.

The names of the gods also vary between translations: “Seven Killings” and “Seven Killers”, “Hurting Officer” and “Harming Officer”, “Rob Wealth” and “Robbing Wealth” are the same thing. Interpretations really do differ, because different schools stand behind them. Our notes and readings follow the classical Zi Ping school.

8 What is free and what is in a reading

The calculator is entirely free: pillars, Ten Gods, hidden stems, elements, luck pillars, years and the short notes. The free chart page shows the same foundation, and couples have a separate compatibility by date of birth calculation.

Paid readings are a written text about your chart, not different maths. The Standard reading is a personal reading of your chart; The Decade Ahead adds chapters on the current and the next luck pillar; the Full reading unfolds the luck pillars across your whole life. Contents and prices are on the readings page. These readings are built on all four pillars, so they need your birth hour. They give context and hypotheses to test against your life, not predictions of events.

Calculate a chart for someone close to you

Every chart you calculate is kept in this browser. For couples there is a separate calculation: two birth dates, the links between the charts and the roles the two Day Masters play for each other.

Back to the calculator

Compatibility by date of birth →

9 Frequently asked questions

Is this BaZi calculator free?

Yes, completely. The pillars, Ten Gods, hidden stems, elements, luck pillars and short notes appear right on the page, with no account and no email. Only written readings of the chart are paid.

Can I calculate my BaZi chart without a birth time?

Yes. Leave the time field empty and the calculator builds a three-pillar chart: year, month and day. You still see your Day Master, elements and luck pillars, but nothing is read from the hour pillar. For births near midnight the day pillar may also be uncertain.

Do I need to convert my birth date to the lunar calendar?

No. A BaZi chart follows the solar seasons, so you enter the ordinary date. The lunar date and Chinese New Year play no part in the calculation.

Why is my BaZi year different from my Chinese zodiac year?

The BaZi year starts at the solar term 立春, around 4 February, while popular horoscopes often count from 1 January or from Chinese New Year. For people born in January and the first days of February the year pillar usually belongs to the previous year.

What is true solar time and why does the calculator use it?

It is the time by the position of the sun at your place of birth. It differs from clock time because of the city’s longitude, daylight saving and Earth’s uneven orbit. Hour boundaries in the chart follow the sun, so without the correction the hour pillar can come out as its neighbour.

Why does another calculator show a different hour or day pillar?

Usually because of one of four rules: whether true solar time is used, where the year boundary is drawn, how the Rat hour between 23:00 and 01:00 is handled, and whether the site knows the time zone history of your city. With the same rules, the eight characters match on any site.

What is the Day Master?

It is the heavenly stem of the day pillar, the central character of the chart. Every other character is read in relation to it: what supports it, what presses on it, what it creates and what it controls.

Is a four pillars calculator the same as a saju calculator?

Yes. Saju is the Korean name for the Four Pillars, and shichū suimei is the Japanese one. Given the same birth data and rules, all of them produce the same eight characters; only the interpretation differs.