Bazi – Birth Year Calculation

Bazi (八字) literally means “eight words” – using eight simple words to summarize any individual’s life.  八字算命 (aka Bazi fortune telling) is only one of the many predictive astrological methods that the Chinese fortune tellers use on a daily basis.  However, it is probably the most popular method because some Bazi advocates have been extremely diligent in marketing this particular method…even though no one method is actually than the other, most methods tend to compliment each other.

Anyways, today I would like to present the calculation of any Chinese lunar birth year.  Actually, it is more appropriate to call it “conversion” rather than “calculation”…but since there are some calculations involved, so whatever.  By the way, this calculation/conversion is rather useless because most Chinese fortune tellers nowadays would simply refer to the Chinese lunar calendar to set the birth chart for any individual.  However, math is always fun, right?  Right.  Anyways, before I move on, here’s a very brief education of how the Bazi system works:

The Bazi system has eight words that make up four “columns”, with each column consists of two words.  The four columns represent the birth year, birth month, birth date, and birth time of any individual (and yes, one should assume that all these information refer to the Chinese lunar calendar…which one can easily find a gazillion out there on the internet).  The top part of the column is called the Heavenly Stem (天干 “Tiangan”) and the bottom part of the column is called the Earthly Branch (地支 “Dizhi).

This is basically how a Bazi chart works, with each column having its own stem & a tree.

This is basically how a Bazi chart works, with each column having its own stem & branch…like a tree.

There is a total of ten heavenly stems and twelve earthly branches.  To be honest, it is not necessary to be mindful about the meaning of each word, since they’re merely representations in a Bazi Chart.  In fact, please feel free to substitute each word with another symbol (ie. 甲 as Food, 乙 as Kite…and etc. XD)…whatever flows your boat.

The ten heavenly stems (just numbering them off for ease of calculation later on):

甲 (Jiǎ) –> 1 –> Yang Wood
乙 (Yǐ)  –> 2 –> Yin Wood
丙 (Bǐng) –> 3 –> Yang Fire
丁 (Dīng) –> 4 –> Yin Fire
戊 (Wù) –> 5 –> Yang Earth
己 (Yǐ) –> 6 –> Yin Earth
庚 (Gēng) –> 7 –> Yang Metal
辛 (Xīn) –> 8 –> Yin Metal
壬 (Rén) –> 9 –> Yang Water
癸 (Guǐ) –> 10 –> Yin Water

The twelve earthly branches (again, just numbering them off for ease of calculation later on):

子 (Zi) –> 1 –> Rat (鼠)
丑 (Chǒu) –> 2 –> Ox (牛)
寅 (Yín) –> 3 –> Tiger (虎)
卯 (Mǎo) –> 4 –> Rabbit (兔)
辰 (Chén) –> 5 –> Dragon (龍)
巳 (Sì) –> 6 –> Snake (蛇)
午 (Wǔ) –> 7 –> Horse (馬)
未 (Wèi) –> 8 –> Sheep (羊)
申 (Shēn) –> 9 –> Monkey (猴)
酉 (Yǒu) –> 10 –> Rooster (雞)
戌 (Xū) –> 11 –> Dog (狗)
亥 (Hài) –> 12 –> Pig (豬)

Before I move on with calculation method of the Chinese lunar birth year, it is important to take 立春 (Beginning of Spring) into consideration.  When it comes to Chinese astrology, Beginning of Spring marks the beginning of a new year (change from one zodiac to the next) rather than the standard first day of the first month of a Chinese lunar calendar year (that’s just Chinese New Year for celebration purposes…not very relevant to astrology).  Any date in the current Gregorian calendar year that’s before the Beginning of Spring should be treated as part of the previous calendar year, and any date on or after the Beginning of Spring should be treated as part of the current Gregorian calendar year.  Beginning of Spring would always fall either on the 4th or 5th in February (Gregorian calendar).  So, if anyone ever encounter someone whose birthday lands on either February 4th or 5th, then ask that person to pay you extra because now you would have to take the extra time to refer to a Chinese lunar calendar for accuracy sake.  I only have ever known one great fortune teller who did not need to refer to any calendar at all (well, he was blind…so I supposed reading calendar was quite useless to him), but he has already passed away.  If he was still alive today, I would have beg him to teach me Chinese astrology.

Okay, now the real fun begins.  There are two parts to this calculation.  The first part of the calculation finds out the heavenly stem of a particular year and the second part is to find out the earthly branch.

Part One – Find out the Heavenly Stem:

Let G = Gregorian Calendar Year

Heavenly Stem = (G – 3) / 10

For example, Person A’s birthday is on February 25, 1994. *That’s after the Beginning of Spring.
Heavenly Stem = (1994 – 3) / 10 = 199.1

Person B’s birthday is on January 13, 1994. *That’s before the Beginning of Spring.
Heavenly Stem = (1993 – 3) / 10 = 199.0

Now, look at the tenth digit place and correspond the digit to the numbers that I have assigned to the ten heavenly stems above.  If the tenth digit place happens to be zero, then treat it as the number 10.  Anyways, based on the number correspondence above, the heavenly stem of Person A’s birth year is 甲 (Jiǎ) (aka Yang Wood).  Meanwhile, the heavenly stem of Person B’s birth year is 癸 (Guǐ) (aka Yin Water).

Part Two – Find out the Earthly Branch:

Let G = Gregorian Calendar Year

Earthly Branch = (G – 3) /12

Using the above examples again…starting with Person A.
Earthly Branch = (1994 – 3) / 12 = 165.91667

Person B.
Earthly Branch = (1993 – 3) / 12 =165.8333

Now, look at the decimal patterns.

When encountered with the following decimal patterns, take the tenth digit place out and add 1 to it:

When encountered with the following decimal patterns, take the tenth digit place out and add 2 to it:

0.000 *treat this as 10…so when add 2 to it, it would be 12, which corresponds to 亥 (Hài) (aka year of the Pig).

Okay, now go back to Person A.
165.91667….take out the tenth digit place and add 2 to it = 9 + 2 = 11
Look at the above number correspondence for the earthly branches.  11 corresponds to 戌 (Xū) (aka year of the Dog).

Person B.
165.8333…take out the tenth digit place and add 2 to it = 8 + 2 = 10
10 corresponds to 酉 (Yǒu) (aka year of the Rooster).

*Bonus:  for those people who have a great memory and want to simplify part two of this calculation (basically just go Earthly Branch = G/12) can just memorize the decimal patterns.  For example,

Person A
1994 / 12 = 166.1667

Person B
1993 / 12 = 166.0833

The decimal pattern correspondence is as follows:

0.3333 = 子
0.4167 = 丑
0.5000 = 寅
0.5833 = 卯
0.6667 = 辰
0.7500 = 巳
0.8333 = 午
0.9167 = 未
0.000 = 申
0.0833 = 酉
0.1667 = 戌
0.2500 = 亥

Based on the above decimal pattern correspondence Person A is 戌 (year of the Dog) and Person B is 酉 (year of the Rooster).

Finally, combining the results from part one and part two, Person A is born in the year of Yang Wood Dog (甲戌) and Person B is born in the year of the Yin Water Rooster (癸酉).

Now, try to find out the Chinese lunar birth year for someone who’s born on March 13, 2015. =D  If you got the answer the year of the Yin Wood Sheep (乙未), then you’re on the right track.


8 thoughts on “Bazi – Birth Year Calculation

    • Thanks! ^^ Glad that this is helpful to you. Hahaha…when I wrote this initially, I was primarily targeting the western audience who’s interested in Chinese astrology, so I’m quite surprised that you would find this helpful too.


      • In fact, I have a big problem when I reading this article …
        The problem is … I’m not good at read a long English article … 😦

        Cause my friend is writing an article about 命理 and must translate to English, and she choose 八字 for the main topic for her article, so I tried to translate some words like 四柱 to English and google it, then google gave me your post … 😛
        So, 四柱 in English is four columns, right? haha, in fact, I’m not sure the word I translated is correct or not.
        And I found you seems like an Asian and you can read Chinese, so … may I response you with Chinese 😛
        I’m not good at English .. 😦

        P.S.: I found another post you posted about predict, and I’m reading hardly right now 😛


      • Oh, I see…

        沒問題, 中文ok啊! If you have any question about this article and the other one, please feel free to ask! ^^ 但事先聲明, 我中文回复可能有點慢和我的中國命理知識其實很半桶水…^^”

        對的! 四柱大概就是 “four columns”. ^^



      • 看到中文果然親切很多啊 … 😛

        原來四柱的確是 four columns 啊,那就好 …
        其實最困擾我的就是天干跟地支,我到最後都直接用羅馬拼音的方式 … 地支曾想過用 earth branches ,但是感覺也怪怪的


        完全不知道該怎麼翻譯八字那些專有名詞 T___T

        比較麻煩的是不知道在西方的話,是不是五行的力量有所變化 ….


      • 哈哈…其實我是overseas Chinese of Cantonese descent. 但正式來說我是加拿大人. XD sure, exchange of knowledge sounds great. ^^ I’ve been learning very slowly from the book, “朱鵲橋命理”. 術數只是我其中愛好之一、所以真說不出有專業的認識.^^”

        其實四柱亦可以翻譯成”four pillars”…回想一下這可能比”four columns”更好聽和更合原意.

        我覺得天干(heavenly stem) 和地支(earthly branch)似乎還好. 我還不太懂太極、十神、神煞這些概念所以想不出英文名稱.但是在這個時代西方對陰陽(Yin and Yang)和五行(Five elements)應該有了一定的認識. 至於大運、流年、流月、流日、和流時…這些有點像西方占星術的transit forecast 或biorhythm. 所以我覺得這些名詞可以翻譯成以下(如有誤解這概念請指出):
        大運=Big transit 或 transit of significance
        流年=yearly transit
        流月=monthly transit
        流日=daily transit
        流時=hourly transit

        西方有類似…風、火、土、和水. 是”四行”而不是五行. 之後有三種基本狀態(或品質)來分配十二星座: Cardinal(根本), fixed (固定), mutable (可變)


        至於不知道自已出生時間…在西方占星學可以通過第一印象來縮小”上升”可能性範圍再來判斷出時間. 我覺得這方法不夠精確、可以再配合八字或紫微術數(如我另一文章所述). 我試過這中西合璧方法幾次而每次都很成功(全都是陌生人或不很熟悉的朋友),唯獨算關於兄弟姐妹這方面. 真不解為什麼兄弟姐妹數量這方面總算不對.=/


        Oh thanks for letting me know! ^^ I’m not sure why that happen either. It might a glitch from the WordPress server.


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