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).
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
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).
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,
1994 / 12 = 166.1667
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.