Classication of Calendars

 

Solar	Gregorian calendar. Basic unit is day. Approximates the tropical year by adding leap days. Ignores the Moon.
Lunar	Islamic calendar. Basic unit is lunar month. Ignores the Sun.
Lunisolar	Chinese and Jewish calendars. Basic unit is lunar month. Approximates the tropical year by adding leap months.

The Chinese calendar is NOT a lunar calendar!

 

Alternative Classication of Calendars

 

Arithmetical	Gregorian, Indian and Jewish calendars. Based on arithmetical formulas. Prediction and conversion between different arithmetical calendars is simple.
Astronomical	Islamic, Indian and Chinese calendars. Based on astronomical data. Prediction and conversion is hard.

 

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