What is a Leap Year? Recent Leap Years in the 21st Century What is a leap year? How many days does a leap year have? A leap year is defined as follows:
- In the Gregorian calendar, a leap year is a year that includes an extra day, which is February 29.
- In the lunar calendar (used by some Asian countries, based on the moon’s cycles), a leap year is a year with a 13th month, effectively adding an extra month. Specifically, in the Gregorian calendar, a year typically has exactly 365 days and 6 hours. For simplicity, we can say there are 366 days in a leap year. Thus, every 4 years in the Gregorian calendar, there is a leap year. A non-leap year has 365 days, with February usually having 28 days. Accordingly, if a year has an increased number of days, it is classified as a leap year.
- Recent Leap Years in the 21st Century Based on the above criteria, the recent leap years in the 21st century are as follows: 2004, 2008, 2012, 2016, 2020, 2024, 2028, 2032, 2036, 2040, 2044, 2048, 2052, 2056, 2060, 2064, 2068, 2072, 2076, 2080, 2084, 2088, 2092, 2096, and 2100.
- The Simplest Way to Calculate a Leap Year A leap year is determined by the time it takes for the Earth to orbit the Sun. It takes the Earth approximately 365 days, 5 hours, 48 minutes, and 46 seconds to orbit the Sun. For ease of calculation, a year in the Gregorian calendar is rounded to 365 days. Since there are 12 lunar cycles within 365 days, the year is divided into 12 months. Because 365 is not evenly divisible by 12, months are divided into those with 31 days (full months) and those with 30 days (short months), with February being an exception, having only 28 days. Thus, each year accumulates an excess of approximately 5 hours, 48 minutes, and 46 seconds. Over four consecutive years, this excess nearly equals one day, which is then added to February of the fourth year. This fourth year, having 366 days with February 29th as the extra day, is called a “leap year.” To determine if a particular year is a leap year in the Gregorian calendar, simply divide the year by 4. A year will be a leap year if it is evenly divisible by 4. However, it is important to note that for centennial years (years ending in two zeros), you must divide by 400 instead. If the year is divisible by 400, then it is considered a leap year in the Gregorian calendar. For example, since the year 2024 is divisible by 4, it is a leap year.
- If you were born on February 29th, congratulations, you have a very special birthday, though you only get to celebrate it once every four years.
