Chinese Calendrics is a tool for the study of the Chinese Calendar. The Chinese Lunar Calendar is not only a lunar calendar but also a solilunar calendar (what some call a 'lunisolar' calendar), consisting of months corresponding exactly to lunar cycles and years which stay more-or-less in sync with seasonal years.
Implicit in the construction of this calendar is a separate solar calendar, less well-known.
Both calendars depend on the times of certain astronomical events, principally dark moons and winter solstices.
For at least several centuries (according to some scholars, since the 5th C. BCE) the times of these events have been ascertained not by observation but rather by calculation, so these calendars can be classified rule-based.
The calendar has the following uses:
- Convert between dates in the Chinese solar and lunar calendars and dates in the Common Era and Julian calendars
- Calculate the date of New Year's Day in the Chinese lunar calendar
- Ascertain the Western dates of the starts of all of the lunar months in a year in the lunar calendar
- Find leap months in the lunar calendar
- Find the Western dates corresponding to Chinese anniversaries, such as birthdays and wedding anniversaries
- Move forward or backward from a given date (and time) either by a period such as a month (Western or Chinese) or by any number of days
- Calculate the phase of the Moon for any time within a 6000-year period
- Search for the next or previous full moon, dark moon, lunar quarter, solar term or solstice or equinox of a certain type
- Search for a solstice or an equinox in combination with a dark moom or a full moon
- Find days for which the element-animal is the same for day, month and year
- Study the effect of changes in the prime meridian (120 degrees East, 116, 109, etc.
