This is a list of calendar and timekeeping around the world.
Calendar
| name
|
description
|
| Gregorian calendar
|
- The year one is the year of presumed birth of Jesus of Nazareth.
- There are 12 months in a year.
- Days for months are 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31.
- The start of a day is the midnight at Greenwich added or subtracted by multiples of 1 hour, and in some cases further add or subtract 0.5 or 0.25 of hours.
- The leap day is placed in the second month.
- There is 1 leap day every 4 years, except when the year is divisible by 100 and not divisible by 400.
- (97 leaps in 400 years.)
|
| Chinese calendar
|
- The year one is the year of presumed birth of Huangdi.
- 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 at Greenwich added or subtracted by multiples of 1 hour, and in some cases further add or subtract 0.5 or 0.25 of hours.
- Leap month is the first month without a solar term of an even number.
- (7 leaps in 19 years.)
|
| Islamic calendar
|
- The year one is the year of Hijra.
- There are 12 months in a year.
- There are 29 or 30 days in a month, determined by the moon phase / There are 30 days in months of an odd number, 29 days in months of an even number.
- The first day of a month is the day with the first sight of the crescent.
- The start of a day is at sunset.
- Month with the leap day is the last month.
- Year with the leap day is the year when the remainder is over 0.5 days.
- (11 leaps in 30 years.)
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Timekeeping
| name
|
description
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| common timekeeping
|
- 1 day is divided by 12 units ‘hour’ evenly.
- 1 hour is divided by 60 units ‘minute’ evenly.
- 1 minute is divided by 60 units ‘second’ evenly.
- 1 leap second is added to the last minute of a day irregularly.
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| Chinese timekeeping
|
- 1 day is divided by 12 units ‘時’ evenly.
- 1 時 is divided into 2 parts: ‘初’, ‘正’ evenly.
- Every 初 and 正 is divided by 4 units ‘刻’ evenly.
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