Herong's Notes on Astrology and Horoscope - Version 2.11, by Dr. Herong Yang
Chinese Year Numbering System
This section describes how years are counted in Chinese calendar.
In Chinese calendar, a year is defined as a tropical year or solar year, which is the time for the Sun to return to the same position along the ecliptic circle as viewed from the Earth. This is the same definition as the Western calendar.
But in Chinese calendar, years are counted with a combination of two numbering systems:
When counting years, elements from both Heavenly Stems and Earthly Branches are used continuously in cycles. The first year is 甲子 (jiazi), the second is 乙丑 (yichou), and so on. At year eleven, the first element 甲 (jia) of Heavenly Stems will be used again. So the eleventh year is 甲戌 (jiaxu). Of course, the thirteenth year is 丙子 (bingzi), because the first element of Earthly Branches is used after the last element.
Since the numbers 10 (Heavenly Stems) and 12 (Earthly Branches) have a common factor of 2, only 1/2 of the 120 possible stem-branch combinations actually occur. The resulting 60-year (or sexagesimal) cycle takes the name jiazi (甲子) after the first year in the cycle, being the Heavenly Stem of "jia" and Earthly Branch of "zi".
The starting point (epoch) for the Chinese calendar is 2697 BCE. So year 2007 in Western calendar is the year 4704 in Chinese calendar.
Here is a map to help you convert years between the Chinese calendar and the Western calendar:
Western Chinese Year Year 1990 4687 庚午 马 Horse 1991 4688 辛未 羊 Sheep 1992 4689 壬申 猴 Monkey 1993 4690 癸酉 鸡 Rooster 1994 4691 甲戌 狗 Dog 1995 4692 乙亥 猪 Pig 1996 4693 丙子 鼠 Rat 1997 4694 丁丑 牛 Ox 1998 4695 戊寅 虎 Tiger 1999 4696 己卯 兔 Rabbit 2000 4697 庚辰 龙 Dragon 2001 4698 辛巳 蛇 Snake 2002 4699 壬午 马 Horse 2003 4700 癸未 羊 Sheep 2004 4701 甲申 猴 Monkey 2005 4702 乙酉 鸡 Rooster 2006 4703 丙戌 狗 Dog 2007 4704 丁亥 猪 Pig 2008 4705 戊子 鼠 Rat 2009 4706 己丑 牛 Ox 2010 4707 庚寅 虎 Tiger
Here is a nice stamp to celebrate the Year of the Pig - 2007, issued by Canada:
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