It is obvious that you need a correct birth time to produce an accurate BaZi reading. But using this birth time may result in a wrong reading, resulting in an incorrect hour pillar and in some cases even the day pillar!. At Authentic Destiny, we are passionate about using the correct time for deriving your BaZi and not simply take the actual birth datetime. This ensures the authenticity and accuracy of the reading.
BaZi calculations are based on solar time which was used before the advent of mechanical clocks. Modern time is very convenient for day to day living but unfortunately it is usually not the correct time to use for BaZi calculations. Compensating for time variations across different locations and years is a rather complex issue.
To illustrate why this is so, it is easier to explain with some examples. As the first example, we look at Singapore, a small island measuring 49 kilometres from east to west. The longitude of Singapore is 103.85 degrees East of Greenwich.
Strictly speaking, Singapore is in the wrong time zone! See this excellent article Why is Singapore in the “Wrong” Time Zone? for a detailed analysis.
Until May 31 1905, local mean time (known as Singapore Mean Time) was used. The reference meridien was 103 deg 51 min E and the time offset from GMT was 6 hr 55 min. Between Sep 13, 1945 to Dec 31, 1981, Singapore adopted the Singapore Standard Time which had a time offset of 7 hr 30 mins and a reference meridien of 112.5 deg E. Then from Jan 1, 1982 the time offset was changed to 8 hr to follow the change that Malaysia made.
So let's say you are born on August 15, 1980 at 1.30 am. It will be wrong to use that time for BaZi calculation. Since the longitude of Singapore is 103.85 degrees, the difference from the reference meridien is 8.65 degrees. Each degree represents 4 minutes, so the total is 34.6, say 35, minutes. Now since the actual Singapore longitude is to the west of the reference meridien, we need to deduct 35 minutes from the birth time.
As a result we will use the birth datetime of August 15, 1980 at 12.55 am for the BaZi calculation. This person is born in the Zi (or Rat) Hour and the Hour Stem is Bing (Yang Fire).
If you had calculated the BaZi without the time adjustment, it will be the Chen (Ox) Hour and Ding (Yin Fire) Hour Stem. For this case, the impact of the time adjustment is minor. But what if the birth time is 12.30 am? The impact will be major, even the day pillar is changed! We will look at this case in the next article.
In the articles to follow, we will look at further examples from Singapore and also examples from the USA, Malaysia, Russia and China.