Language/Multiple-languages/Culture/Calendars-and-Clocks

This is a list of calendar and timekeeping around the world.

Calendar

name	description
Gregorian calendar	The epoch is the year of presumed birth of Jesus of Nazareth. The start of a year is the presumed day of circumcision of Jesus of Nazareth. There are 12 months in a year. Days for months are 31, 28 or 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31. The start of a day is the midnight in Greenwich added or subtracted by multiples of 1 hour, and in some cases further adding or subtracting 0.5 or 0.25 hours. There is 1 leap day every 4 years added to the second month, except when the year is divisible by 100 and not divisible by 400. (There are about 1 leap in 4 years.)
Burmese calendar	The start of a day is the midnight or at sunrise.
Chinese agricultural calendar	The epoch is the year of presumed enthronement of Yellow Thearch. The start of a year is possibly the presumed day of enthronement of Thearch Shun. There are 12 or 13 months in a year. The first month is the month with winter solstice. There are 29 or 30 days in a month, determined by the moon phase. The first day of a month is the day with new moon. The start of a day is the midnight. The leap month is placed after the first month without a solar term of an even number. (There are about 7 leaps in 19 years.)
Hebrew calendar	The epoch is the creation of world in Genesis. The start of the year one is the presumed day of creation of world in Genesis. There are 12 or 13 months in a year. The start of a day is at sunset. There are 13 months for year 3, 6, 8, 11, 14, 17, 19 in a 19-year cycle. The leap month is placed at the end of the year. (There are about 7 leaps in 19 years.)
Japanese calendar	The epoch is the year of the reign of the current Emperor. The start of the year one is the presumed day of circumcision of Jesus of Nazareth. There are 12 months in a year. Days for months are 31, 28 or 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31. The start of a day is the midnight in Greenwich added by 9 hours. There is 1 leap day every 4 years added to the second month, except when the year is divisible by 100 and not divisible by 400. (There are about 1 leap in 4 years.)
Korean agricultural calendar	The epoch is the year of the foundation of Gojoseon. The start of a year is possibly the presumed day of enthronement of Thearch Shun. There are 12 or 13 months in a year. The first month is the month with winter solstice. There are 29 or 30 days in a month, determined by the moon phase. The first day of a month is the day with new moon. The start of a day is the midnight. The leap month is placed after the first month without a solar term of an even number. (There are about 7 leaps in 19 years.)
lunar Hijri calendar	The epoch is the year of Hijrah. There are 12 months in a year. There are 29 or 30 days in a month, determined by the moon phase. The first day of a month is the day with the first sight of the crescent. The start of a day is at sunset.
Republic of China calendar	The epoch is the year of presumed foundation of the Republic of China. The start of the year one is the presumed day of circumcision of Jesus of Nazareth. There are 12 months in a year. Days for months are 31, 28 or 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31. The start of a day is the midnight in Greenwich added by 8 hours. There is 1 leap day every 4 years added to the second month, except when the year is divisible by 100 and not divisible by 400. (There are about 1 leap in 4 years.)
scheduled lunar Hijri calendar	The epoch is the year of Hijrah. There are 12 months in a year. There are 30 days in months of an odd number, 29 days in months of an even number, 29 or 30 days for the last month. The start of a day is at sunset. (There are about 11 leaps in 30 years.)
solar Hijri calendar	The epoch is the year of Hijrah. The start of a year is the vernal equinox. There are 12 months in a year. There are 31 days in the first 6 months, 30 days in the next 5 months, 29 or 30 days in the last month. The start of a day is at sunset. (There are about 8 leaps in 33 years.)

Further reading: Is There a Perfect Calendar?

Timekeeping

name	description
European timekeeping	A day is divided by 12 units ‘hour’ (in English) evenly. An hour is divided by 60 units ‘minute’ (in English) evenly. A minute is divided by 60 units ‘second’ (in English) evenly. A leap second is added to the last minute of a day irregularly.
Chinese timekeeping	A day is divided by 12 units ‘時’ evenly. A 時 is divided into 2 parts: ‘初’, ‘正’ evenly. Every such part is divided by 4 units ‘刻’ evenly.
Thai timekeeping	A day is divided by 4 periods ‘...โมงเช้า’, ‘บ่าย...โมง’, ‘...ทุ่ม’, ‘ตี...’ evenly. Every such period is divided into 6 parts evenly.