The origin of the old yellow calendar

Method of calculating lunar calendar date from solar calendar date

As mentioned above, the date of the lunar calendar is based on the full moon, which takes each new moon as the first day, and the full moon is the fifteenth day (the 16th day of the big month) and the 29th day (the 30th day of the big month). However, at present, the date of the solar calendar is usually used to express the time. If you want to convert the date of the solar calendar into the date of the lunar calendar, you can use the following two methods: one is to view the newly edited perpetual calendar, for example, what day is June 8 of the lunar calendar 1984? Turning to the perpetual calendar, June 10 is the first day of November in the lunar calendar, so it is inferred that June 8 is the ninth day of September in the lunar calendar. Secondly, we can use the following formula to calculate the lunar calendar date:

Suppose: the number of AD years-1977 (or1901) = 4q+r.

Then: Lunar date =14q+10.6 (r+1)+the day of the year-29.5n.

(Note: In the formula, Q, R and N are all natural numbers, R.

Example:1The lunar calendar date of May 7, 994 is:

1994- 1977= 17=4×4+ 1

Therefore, q = 4, r = 1, so the date of the seventh day of the fifth lunar month is:

14×4+ 10.6（ 1+ 1）+（3 1+28+3 1+30+7）-29.5n

= 204.2-29.5 Newton

Then divide 204.2 by 29.5 to get the quotient 6...27.2, where 6 is the value of n and the remainder 27 is the 27th day of the lunar calendar.