This book is a reference. Almost every page is a table: the moments of the solar terms are calculated from the position of the Sun, and the day pillars are counted through the cycle of sixty, one date after another. This chapter is the only running text. It explains what each part of the book shows, in the order of the book, and then it works through three example births from start to finish, so that you can see every step with actual numbers.
The aim is modest and practical. With this book open on the desk and a birth date, a clock time and a birthplace in your notes, you should be able to find the four pillars of the birth by hand: the year pillar, the month pillar, the day pillar and the hour pillar. The pillars are the starting point of a BaZi chart. Reading them is a separate skill, and this book does not teach it. It gives you the pillars and shows where the boundaries lie.
The four pillars at a glance
A BaZi chart has four pillars. Each pillar is a pair of characters: a heavenly stem on top and an earthly branch below. The stems are ten (甲乙丙丁戊己庚辛壬癸) and the branches are twelve (子丑寅卯辰巳午未申酉戌亥). They pair in a fixed cycle of sixty, from 甲子 to 癸亥. The same cycle of sixty runs through years, months, days and hours, which is why one table of sixty pillars serves the whole book.
Written on one line, as everywhere in this book, a pillar puts its stem first: in 甲子 the stem is 甲 and the branch is 子. A chart is written in the order year, month, day, hour, from left to right, and the four pillars of the examples below appear in that order.
The four pillars come from four different clocks.
The year pillar belongs to the solar year, which begins at 立春 (lì chūn, Start of Spring), a precise moment in early February. It does not begin on 1 January.
The month pillar belongs to the solar month. The twelve solar months begin at twelve of the twenty-four solar terms, the ones called 節 (jié). Each begins at a precise moment, not at midnight.
The day pillar belongs to the date. Days run through the cycle of sixty one after another, without a break, and the pillar of a day follows the calendar date at the place of birth.
The hour pillar belongs to the double hour. The Chinese day is cut into twelve double hours, each called a 時辰 (shí chén) and named by a branch. The stem of the hour depends on the stem of the day.
The year and the month depend on exact moments, the day on a date and the hour on a clock reading, and mixing these up is where most mistakes happen. The next sections go table by table, and the worked examples show where the traps are.
This calendar and your free chart
Before the contents page there is a short page called "This calendar and your free chart". It gives five quick steps and a QR code that opens the free calculator at bazi.cards. The five steps are the same method that this chapter explains at length. The calculator uses the same solar terms and the same rules as the tables, and it adds what a printed table cannot know: the history of the clocks at the birthplace, with its time zone and summer time, and the true solar time of that place, worked out from its longitude and the date. Use the book to understand and to check. Use the calculator when you want the answer for a place and a year where the clock history is complicated.
The reference tables
After this chapter come seven reference tables. Each of them answers one question. You will not need all of them for every birth, and it is worth knowing which one to open when.
The sixty pillars
This is the cycle from 甲子 to 癸亥, numbered from 1 to 60. For each pillar the table gives the pinyin reading, the stem and branch with their polarity (Yang or Yin) and element, and the animal of the branch. A stronger line closes each run of ten pillars. A run of ten is called a 旬 (xún), and the line helps the eye when you count forward or backward through the cycle.
Open it whenever you need to count through the cycle, for instance to write out the Luck Pillars that follow a month pillar, forward or backward. It is also the quickest way to see the element and polarity of a stem, which the later books of the series build on.
Hidden stems of the twelve branches
Every branch holds one, two or three stems inside it, called hidden stems (藏干, cáng gān). The main stem (本氣, běn qì) carries the element of the branch, and the middle stem (中氣, zhōng qì) and the residual stem (餘氣, yú qì) are weaker. The branches 子, 卯 and 酉 hold one stem each. The branches 午 and 亥 hold a main and a middle stem. The other seven branches hold three. The name of the middle stem, 中氣, is also the name of the solar terms in the middle of each month, described below: the same two characters name two different things.
You do not need this table to find the four pillars. It is here because it is the very next thing a reader of a chart wants, and a reference book that stops at the pillars would send you to look for it elsewhere. Open it when you start to read a chart.
Month pillars by year stem
The stem of the month follows the stem of the year. The rule is called 五虎遁 (wǔ hǔ dùn), the rule of the five tigers: the first month of every year is a Tiger month, 寅, and there are five Tiger pillars, one for each pair of year stems. A year whose stem is 甲 or 己 opens with the month 丙寅. A year with 乙 or 庚 opens with 戊寅. A year with 丙 or 辛 opens with 庚寅, a year with 丁 or 壬 opens with 壬寅, and a year with 戊 or 癸 opens with 甲寅. The remaining eleven months follow in the cycle of sixty.
The year pages already print every month pillar for every year, so you do not need this table to find a month. It is there so that you can see the pattern, and so that you can check a month pillar by a second route. If the page of a year says that its Tiger month is 丙寅, the table will agree if the year stem is 甲 or 己.
The twenty-four solar terms
The Sun travels once around the sky in a year. Every 15 degrees of its path, measured as ecliptic longitude, is the start of a solar term, so the year holds twenty-four of them. They alternate between two kinds.
The twelve terms called 節 (jié) begin the months of the BaZi calendar. 立春 is the first of them and begins both the year and the Tiger month. The twelve terms called 中氣 (zhōng qì) fall in the middle of each month. They are real astronomical moments, and they have names that many people know, such as the equinoxes and the solstices, but they change no pillar. When you work out a chart you look for the 節 and you can ignore the 中氣.
The table lists all twenty-four with their Chinese names, pinyin, English names, the longitude of the Sun, the role of each term and the range of dates on which it falls between 1930 and 2050. The dates are in Beijing time. The range is useful as a sanity check. 驚蟄 (jīng zhé, Awakening of Insects), for example, always falls on 5 or 6 March in these years, so a 驚蟄 you have copied from a year page with another date means that you have read the wrong row.
The exact moments of the terms in this book come from DE440, the planetary and lunar ephemeris of NASA's Jet Propulsion Laboratory (JPL), and are rounded to the minute.
Hour pillars
This table is the 五鼠遁 (wǔ shǔ dùn), the rule of the five rats, in full. The rows are the double hours with the clock times that each covers, from the early 子 at the top, through 丑, 寅 and the rest, down to 亥, with one more row for the late 子 at the bottom. The columns are the stem of the day, grouped in pairs: 甲 or 己, 乙 or 庚, 丙 or 辛, 丁 or 壬, 戊 or 癸. To find the hour pillar, take the stem of the day pillar, pick its column, take the row of the birth time, and read the pillar where they meet.
The 子 hour needs a note. It runs from 23:00 to 00:59, and midnight cuts it in two. The table therefore has two 子 rows. The first row is the early 子, from 00:00 to 00:59, which belongs to the day that has just begun. The last row is the late 子, from 23:00 to 23:59, which is the 子 hour of the next day. In that row the table already gives the pillar of the next day's 子 hour, so you still read it in the column of the day of birth. The third worked example below goes through it step by step.
Clock time and true solar time
The double hours follow the Sun, and the clock follows a time zone. These two are close but rarely equal. This page gives the two corrections that bring them together. The first is the longitude rule. For every degree that a place lies east of the central meridian of its time zone, add four minutes. For every degree west, subtract four. The central meridian lies 15 degrees from Greenwich for each hour of the zone: 120° E for UTC+8, 15° E for UTC+1, 75° W for UTC−5. If summer time was in force, take it off first. The second is the equation of time, a correction that comes from the shape of the Earth's orbit and the tilt of its axis. Its size changes through the year. The table lists it for the 1st, 8th, 15th and 22nd of each month. A plus sign means the Sun is ahead of the clock and the minutes are added.
The calculator uses a standard approximation of the equation of time, and its result can differ from the table by up to 1.2 minutes. That matters only for a birth within a minute or two of the edge of a double hour.
Not everyone uses true solar time to read the hour pillar. This book prints the table and shows what happens with and without it, and a later section sets the two ways side by side.
Luck Pillars: direction and starting age
Luck Pillars (大運, dà yùn) are ten-year pillars that continue the month pillar of birth, forward or backward through the cycle of sixty. The page gives the rule for the direction. It depends on the stem of the BaZi year and on the sex of the person. A man born in a Yang year and a woman born in a Yin year have their pillars run forward. A man born in a Yin year and a woman born in a Yang year have them run backward. The Yang stems are 甲 丙 戊 庚 壬 and the Yin stems are 乙 丁 己 辛 癸. For a birth before 立春, the year stem is the stem of the previous BaZi year.
The starting age comes from counting the time between the birth and a 節. The count goes to the next 節 for a forward direction and back to the last 節 for a backward one. Three days of that span equal one year of age, one day equals four months, and two hours equal ten days. The page has the conversion tables, and it works two examples. Both appear again below.
The years
The larger part of the book is the calendar proper, 121 years from 1930 to 2050, two facing pages for each. Before the first year there are two aids.
The year finder
The year finder lists every year from 1930 to 2050 with its year pillar and the page where its spread begins. If you know the year of birth in the ordinary calendar, it tells you which pillar to expect and where to turn. Remember that this pillar begins at 立春, early in February. A person born in January, or in February before 立春, has the year pillar of the year before, and the year finder cannot show that. The page of the year does, and the second example below shows how.
Reading a year spread
The page called "Reading a year spread" is a key to the pages that follow. It explains the two pages in ten points. Here is the same key in plain words.
The left page of a spread is about the year and its months. At the top are the year, its pillar and the pinyin, polarity, element and animal of that pillar. Under it comes the exact moment of 立春, when this year pillar begins, and the pillar of the year before it, which applies to a birth earlier than that moment.
Then come the solar months. Each row gives one month: the branch with its animal, the month pillar, the 節 that begins the month, with its English name, its date and the minute it begins, and the 中氣 in the middle of the month, in the same form. There are thirteen rows, because thirteen solar months touch each calendar year. The first row is the 子 month, which began in December of the year before. The second is the 丑 month, which began with 小寒 (xiǎo hán, Minor Cold) in January. Both of these belong to the previous BaZi year, and they stand under a gold label with the pillar of that year: on the page for 1989 it reads "戊辰 year, continued". A second gold label, "己巳 year" on the same page, opens the shaded row of the 寅 month, the one that starts with 立春. After it come the months of the new BaZi year. At the foot of the page is the next 立春, and the note "Beijing standard time (UTC+8), rounded to the minute". In some years a note about China's clocks follows, and the next section explains it.
The right page of a spread is the grid of days. The columns are the Gregorian months and the rows are the days of the month. Each cell holds the day pillar of that date. At the head of every column stand the name of the month, the 節 of that month with its day and its time in Beijing, and the month pillar it starts. The shading marks the solar month. A day on which a new solar month begins is framed and split by a diagonal line, with the old shade on one side and the new one on the other. A double frame marks 立春. The day numbers are printed at both edges of the grid, so you can run a finger across without losing the row. On a framed day the shading cannot tell you the month of a birth: compare the moment of birth, in Beijing time, with the minute in the head of the column.
All times on the year pages are Beijing standard time (UTC+8), rounded to the minute, and they never include summer time. The day pillar needs no conversion of time zone, only the local date.
Beijing time, local time and summer time
Here is the rule that causes most confusion, so it gets its own section.
The moments of 立春 and of every other term are single instants, the same for the whole Earth. Beijing time is only the way this book names them. A birth in London and a birth in Sydney that happen at the same instant are on the same side of 立春, whatever their clocks say. To compare a birth with a term you must put both on the same clock. The simplest way is through UTC. Take the birth time on the clock of the birthplace, remove the summer time if it was in force, subtract the offset of the zone to reach UTC, then add eight hours to reach Beijing time. For a zone west of Greenwich the offset is negative, so subtracting it means adding: 09:00 on UTC−5 is 14:00 UTC. Or go the other way: take the term in Beijing time, subtract eight hours to reach UTC, and add the offset that the clocks of the birthplace showed at that moment, summer time included.
What is converted and what is not depends on the pillar.
The year pillar and the month pillar depend on the absolute instant. Convert the birth to Beijing time, then compare it with the terms.
The day pillar depends on the local calendar date of the birth, as it was written in the birth record. The time zone does not change it. A person born at 22:00 on 10 June in New York has the day pillar of 10 June, even though in Beijing that moment is already the next day.
The hour pillar depends on the local standard time of the birth, read in the table of hours, with the stem of the day.
Summer time deserves a second look. Many countries moved their clocks forward in summer, usually by one hour, in years and on dates that varied from country to country. If a birth certificate says 14:35 and the clocks were one hour ahead on summer time, the same moment on standard time was 13:35. Take the hour off first, both for the conversion to Beijing time and before you read the hour pillar. The first and second worked examples below include summer time on purpose. This book does not list the summer time rules of other countries, and it would be wrong to guess them. The one exception is China, which kept summer time (UTC+9) from 1986 to 1991, and the pages of those years print the dates. In the 1940s clocks in parts of China ran on summer time or wartime time, and practice differed from region to region, so the pages of those years carry a careful note instead of dates. When a birth record comes from China in those years, find out which clock it used. Elsewhere the rules differed from country to country and changed over the years, and the calculator applies the recorded history of the time zone of the birthplace.
The method in five steps
Put together, the work is always the same.
First, take the date, the clock time and the birthplace, and find out which clock was in use at that place on that day. That means the time zone and, if there was one, the summer time.
Second, convert the moment of birth to Beijing time (UTC+8) and open the page of the year of birth. If the birth comes after the 立春 printed at the top of the page, the year pillar is the pillar of that page. If it comes before, the year pillar is the one the page names for the time before 立春, and the month is one of the two rows under the first gold label, "… year, continued". In either case the month row is the one whose 節 is the latest to have begun at the moment of birth, and the row gives the month pillar.
Third, find the day pillar in the grid on the right page. Use the local date.
Fourth, find the hour pillar in the table of hours. Take the local clock time with any summer time removed, find its row, and read it in the column of the stem of the day pillar. A birth from 23:00 to 23:59 takes the last row, the late 子, in the same column.
Fifth, check the result in the free calculator at bazi.cards, which opens at en.bazi.cards/b/calc. Enter the date, the time and the place. If the calculator and your hand result disagree, look first at the time zone, the summer time and the birth time, which are the usual reasons. Remember too that the calculator reads the hour from true solar time.
Example 1. A summer afternoon in London, 1975
Take a man born in London on 21 August 1975, at 14:35 by the clock.
In August 1975 Britain was on British Summer Time (BST), one hour ahead of UTC. So the instant of birth is 13:35 UTC. Beijing is eight hours ahead, so in Beijing this moment was 21:35 on the same date.
The year. Open the page for 1975. The 立春 of 1975 fell on 4 February at 18:59, Beijing time. The birth is in August, long after it, so the year pillar is the pillar that begins in 1975, which is 乙卯. The Chinese New Year does not matter here.
The month. On the same page look at the month rows. The latest 節 before the birth is 立秋 (lì qiū, Start of Autumn), on 8 August 1975 at 11:45, Beijing time. In London that moment was 04:45 summer time. The next 節, 白露 (bái lù, White Dew), does not come until September. The row of 立秋 is the 申 month, and it gives the month pillar 甲申.
The day. In the grid on the right page, the cell for 21 August gives the day pillar 己亥. The date is the local date, which is also 21 August.
The hour. The clock reads 14:35 summer time, which is 13:35 on standard time, and either way the birth falls in the 未 double hour, from 13:00 to 14:59. The stem of the day is 己, so the column is "甲 or 己 day". In that column the row 未 gives 辛未.
The four pillars are 乙卯 甲申 己亥 辛未.
If you want to read the hour from true solar time, as the calculator does, the clock time of 14:35 has the summer hour taken away, and the longitude and the equation of time correct it a little more. The result is about 13:31. That still lies in the 未 hour, so the hour pillar and the whole chart stay the same.
The direction of the Luck Pillars. The year stem 乙 is Yin, and for a man a Yin year means that the pillars run backward. The span goes from the birth back to the 節 that began the month, 立秋 at 04:45 on 8 August, in the local time of London. From then to the birth is 13 days, 9 hours and 50 minutes. On the conversion tables of the Luck Pillars page, 13 days equal 4 years and 4 months, and 9 hours 50 minutes add about 49 days, which is a little over a month and a half. The start is therefore at about 4 years and 6 months. The calculator gives the age as 4.47 years. The first Luck Pillar is 癸未, and it begins in about February 1980. The pillars that follow are 壬午 near 1990, 辛巳 near 2000, 庚辰 near 2010 and 己卯 near 2020. The same example is worked on the Luck Pillars page, which has the arithmetic in full.
Example 2. The morning of 立春, Sydney, 1989
The second example shows the boundary of the year and the month, the southern hemisphere and summer time, all in one morning. It is also the example in which less than two hours change almost everything.
On 4 February 1989 the 立春 fell at 04:27, Beijing time. In February 1989 Sydney was on summer time (AEDT), eleven hours ahead of UTC. By the Sydney clock this moment was 07:27. The Chinese New Year of 1989 fell only on 6 February, but the BaZi year does not wait for it. The year changes at 立春.
Two girls are born in Sydney on that morning, both on 4 February 1989.
The first is born at 06:50 by the Sydney clock. Take away the eleven hours and the moment is 19:50 UTC on 3 February, which is 03:50 on 4 February in Beijing. That is before the 立春 at 04:27, so she still belongs to the previous BaZi year. The page for 1989 shows the year pillar that comes before 立春: 戊辰. The latest 節 before her birth is 小寒 on 5 January 1989 at 16:46, Beijing time, which began the 丑 month. Its row, under the gold label for 戊辰, gives the month pillar 乙丑. The grid gives the day 乙未. The clock reads 06:50 summer time, which is 05:50 on Sydney standard time; either way it is the 卯 hour, from 05:00 to 06:59, and a 乙 day takes the column "乙 or 庚 day", which gives 己卯. Her four pillars are 戊辰 乙丑 乙未 己卯.
The second is born at 08:40 the same morning. In Beijing that is 05:40, which is after the 立春. Now the year is 己巳, the month is the Tiger month 丙寅, the day is still 乙未, and the hour is 辰, from 07:00 to 08:59, on the summer clock and on standard time alike, which gives 庚辰. Her four pillars are 己巳 丙寅 乙未 庚辰.
The two girls share a date and a day pillar. They differ in the year, in the month and in the hour. Even the direction of the Luck Pillars differs. The first has a Yang year, 戊, and is female, so her pillars run backward, to 小寒, which in Sydney was 19:46 on 5 January 1989. From there to her birth is 29 days, 11 hours and 4 minutes, which gives about 9 years and 10 months (the calculator gives 9.82), and her first Luck Pillar is 甲子. The second has a Yin year, 己, and is female, so her pillars run forward, to the next 節, 驚蟄 on 5 March 1989 at 22:34 in Beijing, which is 01:34 on 6 March in Sydney. From her birth to that moment is 29 days, 16 hours and 54 minutes, which gives about 9 years and 11 months (the calculator gives 9.90), and her first Luck Pillar is 丁卯.
True solar time in Sydney is further from the summer clock. First the summer hour comes off, which leaves Sydney standard time, UTC+10, whose central meridian is 150° E. Sydney lies at 151.2° E, a little east of it, which adds about 5 minutes. The equation of time on 4 February takes off about 14 minutes. In total the Sun is about 69 minutes behind the summer clock. The 06:50 birth becomes about 05:40 and the 08:40 birth becomes about 07:30. The hours 卯 and 辰 do not change. In this case the choice between clock time and true solar time makes no difference.
A note on the southern hemisphere
In Sydney, February is the middle of summer, yet the month that begins on 4 February is called 立春, Start of Spring. A reader may fairly ask whether the calendar should be turned upside down below the equator.
This book keeps to the classical method. A solar term is fixed by the position of the Sun on its path, and that moment is the same for everyone on the Earth. The classical texts assume the months of the Chinese solar calendar, and the names of the terms describe the seasons of China, where they were named. Some modern teachers shift the seasons for the southern hemisphere, so that the chart of a person in Sydney is read with the opposite season. That is a choice of interpretation, and this book does not make it. A birth in Beijing and a birth in Sydney at the same instant have the same year pillar and the same month pillar here. How a reader then weighs the season in the chart is a question for the other books of the series and for the teacher.
Example 3. A late night in Shanghai, 2003
The third example is a birth close to midnight, which is where the hour table asks for care. A woman is born in Shanghai on 9 March 2003 at 23:40. Shanghai is on UTC+8, and China had no summer time in 2003, so the clock time is Beijing time.
The year. The 立春 of 2003 fell on 4 February at 14:05, a month before the birth, so the year pillar is 癸未.
The month. The latest 節 before the birth is 驚蟄 on 6 March 2003 at 08:05, Beijing time, which begins the 卯 month. Its row gives the month pillar 乙卯.
The day. The grid gives the day pillar 辛巳 for 9 March. The date is the local date, and it is still 9 March at 23:40.
The hour. 23:40 falls in the late 子 hour, from 23:00 to 23:59, which is the last row of the hour table. The day pillar is 辛巳, so the column is "丙 or 辛 day", and the last row of that column gives 庚子. The hour pillar is 庚子.
This is the point that surprises many readers. The late 子 hour is the 子 hour of the next day. The next day, 10 March, has the day pillar 壬午, and in the column "丁 or 壬 day" the first row, the early 子, gives the same 庚子. The last row of the table has made that step for you. Read it in the column of the day of birth, as you read every other row; taking the column of the next day as well would count the day twice and give the wrong pillar.
The four pillars are 癸未 乙卯 辛巳 庚子.
For comparison, a birth at 00:20 on 10 March, only 40 minutes later, has a different day pillar, 壬午, and the same hour pillar, 庚子: 癸未 乙卯 壬午 庚子. The hour pillar stays and the day changes, because midnight falls between the two births.
This is also the point at which schools part. The rule of this book follows the rule of the calculator at bazi.cards: the day pillar changes at midnight, and a birth from 23:00 to 23:59 keeps the day pillar of its date. Some schools start the new day at 23:00 instead. For a birth at 23:40 on 9 March they would give the day 壬午, with the same hour 庚子. This book keeps the midnight rule for all its tables and does not call the other rule wrong. If you are working with a birth that falls from 23:00 to 23:59, it is sensible to look at both charts and, if the difference matters to you, to ask a practitioner which rule they use.
True solar time in Shanghai moves the time only a little. The city lies at 121.5° E, 1.5 degrees east of the meridian of UTC+8, which adds 6 minutes. The equation of time on 9 March is about minus 11 minutes. The result is about 23:34, still the late 子 hour.
The Luck Pillars of this woman also appear on the Luck Pillars page. Her year stem 癸 is Yin and she is female, so the pillars run forward, to the next 節, 清明 (qīng míng, Clear and Bright) on 5 April 2003 at 12:52. The span is 26 days, 13 hours and 12 minutes, which gives about 8 years and 10 months (the calculator gives 8.85), and the first Luck Pillar is 丙辰.
True solar time, and the same night in Kuala Lumpur
True solar time is the time a sundial shows: at 12:00 true solar time the Sun reaches its highest point in the sky of the birthplace. The calculator converts the birth time to it before it reads the hour pillar. After taking off any summer time, it makes the two corrections already described: four minutes for each degree of longitude from the central meridian of the time zone, then the equation of time.
The correction can matter. It does not change the year or the month, because those depend on the instant of the solar term and not on the clock of the place. It can change the hour pillar, and close to midnight it can change the date, and with it the day pillar.
Take the same clock reading as in the third example, 23:40 on 9 March 2003, but in Kuala Lumpur, which also keeps UTC+8. Kuala Lumpur lies at 101.7° E, which is 18.3 degrees west of the meridian of UTC+8. That is 73 minutes subtracted. The equation of time takes off another 11 minutes. The true solar time is about 22:15, which is in the 亥 hour, not the late 子 hour. The hour pillar for a 辛 day is 己亥, and the four pillars are 癸未 乙卯 辛巳 己亥. With the clock as it is, the same reading would give 癸未 乙卯 辛巳 庚子. The calculator makes the same two corrections when Kuala Lumpur is given as the birthplace.
So which one is right? That is a question of school, and each side has reasons. Those who read by the clock keep to the time that was recorded at the birth, in the zone the birthplace used. Those who read by true solar time point out that the double hours were defined by the Sun. The book gives both roads. If you keep to the clock, take the local time with any summer time removed and use the hour table as it stands. If you want to proceed as the calculator does, first correct the time with the table "Clock time and true solar time", then read the hour table. Choose one road and keep to it for every chart you compare.
True solar time never moves the 節. Those moments are instants, and they stay the same.
Luck Pillars, briefly
The Luck Pillars page has the rule for the direction, the way to count the starting age and two worked examples, London 1975 and Shanghai 2003, which are the first and the third examples of this chapter. There are four practical points to add.
Measure the span with both moments on the same clock. The simplest is Beijing time: the birth converted as for the month, and the 節 as the year page prints it. Local time gives the same span, provided the 節 is converted to the clock of the birthplace and no change of summer time falls between the two moments; when one does, stay with Beijing time.
The direction depends on the BaZi year. A birth before 立春 takes the stem of the previous year, which is why the two girls of the second example have opposite directions although they were born on the same day.
Teachers round the starting age in different ways, to the year, to the month or to the day. The calculator gives it in years with two decimals, and the Luck Pillars page gives it in years and months from its conversion tables. Your own figure may differ by a few weeks from another source and still be correct under its rule.
A birth in December 2050 after the 大雪 (dà xuě, Major Snow) needs the next 節, 小寒 of 2051, for a forward count. The book has no page for 2051, so that moment is printed at the foot of the page for 2050.
When a birth sits close to a boundary
Every moment in this book is printed to the minute, and every birth time that arrives from a document is a figure with its own limits. Tables built on other astronomical models can differ from these by a minute. Many birth records are rounded to the nearest five or ten minutes. Some are written down from memory. A clock of the time may also have been wrong.
For that reason, three kinds of birth call for care.
The first is a birth within a few minutes of a 節, and above all of 立春. On the two sides of a 節 the month pillar differs, and on the two sides of 立春 the year pillar as well.
The second is a birth close to midnight, where the date and the late 子 hour are in play. The third example shows one.
The third is a birth close to the edge of a double hour, where the hour pillar changes. The correction to true solar time runs from a few minutes to more than an hour, as in Kuala Lumpur, and can push such a birth over the line.
In all three cases the sensible course is to treat both charts as candidates. Check the document for the exact time. Check the place, the time zone and the summer time. Run the calculator. If the doubt remains, take it to a practitioner. A close call is common, and it does not mean that something went wrong.
What this book does not do
This is a calendar. It gives the four pillars of a birth, and the moments that decide them, and it does so as carefully as the data allow. It does not interpret a chart. It does not tell you what happens in a life, and it does not predict events. It gives no medical, financial or legal advice. The Day Master, the stem on top of the day pillar and the centre of the reading of a chart, is the subject of the series called The Day Master Books, and the Ten Gods and the strength of the chart are discussed there.
Nor does the book claim to know the official time of every place. Clocks were set by local and national decisions, and the records of past decades are often incomplete. The calendar knows the Sun with great precision. It cannot know every clock. The calculator follows the history of the time zone of a birthplace as far as it is recorded, and you should still treat its output as a calculation and not as a certificate. Where a hand result and the calculator disagree, the difference usually comes from the clock, the summer time or the true solar time, and the examples above show how to find which.
With a birth date, a clock time and a birthplace in your notes, turn to the year finder and open the page of the year of birth.