Leap Year Calculator

1. Year is Leap Year or Not : Calculate whether the input year is a leap year or a normal year. Supports the calculation of B.C. years. Enter a negative number for the B.C. year and a positive number for the A.D. year.
2. Leap Years in the range : Query the list of leap years within the input year range. Supports the calculation of B.C. years. Enter a negative number for the B.C. year and a positive number for the A.D. year.
3. The difference between leap years and normal years : A leap year has 366 days and February has 29 days. In the normal year, there are 365 days in a year, and 28 days in February.
4. The Gregorian calendar year is divided into BC and AD years. Note: There is no 0 BC or 0 AD. Only 1 B.C. and A.D. 1 .
5. Leap Year Calculation Rules : For years after AD, it can be divisible by 4 and cannot be divisible by 100 as leap years. Can be divided by 400 is leap years. The years of BC are calculated backwards according to this rule. The abbreviation is: one leap in four years, no leap in a hundred years, and another leap in four hundred years.
6. Why there is a leap year : The cycle of the Earth's orbit around the sun is 365 days, 5 hours, 48 minutes, 46 seconds (365.24219 days), which is the tropical year. The Gregorian calendar has only 365 days in the normal year, which is about 0.2422 days shorter than the tropical year. The remaining time is about one cumulative day every four years, so one additional day is added at the end of February in the fourth year, Change the length of the current year to 366 days, and this year is called a leap year. In the current Gregorian calendar, there are 97 leap years every 400 years. Calculated as one leap year every four years, On average, an additional 0.0078 days should be calculated every year, which would result in an additional 1 day every 128 years and an additional 3 days after 400 years. Therefore, there are three leap years to be reduced every 400 years. Therefore, the Gregorian calendar stipulates that when the year is a whole hundred, it must be a multiple of 400 to be a leap year; A century year that is not a multiple of 400, even a multiple of 4, is not a leap year.