The Chinese calendar is lunisolar, incorporating elements of a lunar calendar with those of a solar calendar. This measure of time is not exclusive to China, but followed by many other Asian cultures. It is often referred to by the Western cultures as the Chinese calendar because it was first used by the Chinese. In most of Asia today, the Gregorian calendar is used for day to day activities, but the Chinese calendar is still used for marking traditional East Asian holidays such as the Lunar New Year (Spring Festival), and in China the Duan Wu festival, and the Mid-Autumn Festival, and in astrology, such as choosing the most auspicious date for a wedding or the opening of a building. Because each month follows one cycle of the moon, it is also used to determine the phases of the moon.

In China, the traditional calendar is known as the "agricultural calendar" ( ) while the Gregorian calendar is known as the "common calendar" ( ) or "Common calendar" . Another name for the Chinese calendar is the "Yin Calendar" ( ) in reference to the lunar aspect of the calendar, whereas the Gregorian calendar is the "Yang Calendar" ( ) in reference to its solar properties. The Chinese calendar was also called the "old calendar" ( ) after the "new calendar" ( ), i.e. the Gregorian calendar, was adopted as the official calendar. The traditional calendar is also often referred to as "the Xia Calendar", following a comment in the Shiji which states that under the Xia Dynasty, the year began on the second moon after the winter solstice (just as in the modern calendar).

The current year in the Chinese calendar is 4706 the Year of the Earth Rat (year of Wù Zǐ, 戊子). It lasts from 7 February 2008 to 25 January 2009. Based on traditional beliefs, some form of the calendar has been in use for almost five millennia. Based on archaeological evidence some form of it has been in use for three and a half millennia.

Early history

The earliest evidence of the Chinese calendar is found on oracle bones of the Shang dynasty (late second millennium BC), which seem to describe a lunisolar year of twelve months, with a possible intercalary thirteenth, or even fourteenth, added empirically to prevent calendar drift. The Sexagenary cycle for recording days was already in use. Tradition holds that, in that era, the year began on the first new moon after the winter solstice.

Early Eastern Zhou texts, such as the Spring and Autumn Annals, provide better understanding of the calendars used in the Zhou dynasty. One year usually had 12 months, which were alternatively 29 and 30 days long (with an additional day added from time to time, to catch up with "drifts" between the calendar and the actual moon cycle), and intercalary months were added in an arbitrary fashion, at the end of the year.

These arbitrary rules on day and month intercalation caused the calendars of each state to be slightly different, at times. Thus, texts like the Annals will often state whether the calendar they use (the calendar of Lu) is in phase with the Royal calendar (used by the Zhou kings).