Content
There is one extra day in a leap year. There are approximately 365.24 days in a typical year, so one extra day needs to be added every four years. This is necessary in order to keep up with the year by several hours. Calculating leap years is fairly easy, but there are a few special rules to remember. If you don't like doing calculations, just look at the calendar.
Steps
Method 1 of 2: Using the division operation
1 Define the year you want to check for leap years. For example, consider the past, current, or next year. - For example, check 1997 or 2012 (as last year), or 2019 (as current year), or 2025, or 2028 (as next year).
2 Divide the year by 4. If the division is an integer, that is, without a remainder, the year is a leap year. If the division results in a remainder (or decimal fraction), the year is not a leap year. - For example, 1997/4 = 499.25. The result is a decimal, so 1997 is not a leap year.
- 2012/4 = 503. This is an integer, so 2012 is most likely a leap year.
3 Find out if the year is divisible by 100. If a year is divisible by 4 but not divisible by 100, it is a leap year. If the year is divisible by both 4 and 100, it may not be a leap year, so you have to do another calculation. - For example, 2012 is divisible by 4 and not divisible by 100 (2012/100 = 20.12). Therefore, 2012 is definitely a leap year.
- 2000 is divisible by 4 and by 100 (2000/4 = 500 and 2000/100 = 20). This means 2000 may not be a leap year, so do another calculation.
4 Check if the year is divisible by 400. If the year is divisible by 100 and not divisible by 400, it is not a leap year. If the year is divisible by 100 and 400, it is a leap year. - For example, 1900 is divisible by 100 but not divisible by 400 (199/400 = 4.75). This means that 1900 is not a leap year.
- On the other hand, 2000 is divisible by 100 and 400 (2000/400 = 5). This means that 2000 is a leap year.
clue: If you do not want to divide the number manually or are not sure about the results obtained, use the online leap year calculator - it will do all the calculations.
Method 2 of 2: Using a calendar
1 Find the year you want to check on the calendar. Decide on the year you want to check, then grab a paper calendar or open an online calendar that shows both previous and future years. - For example, to find out if 2016 was a leap year, search for that year's calendar.
- To check if 2021 is a leap year, open that year's online calendar.
2 Open February and find the 29th in it. There is one extra day in leap years, which is included in February because it is the shortest month. If there is a 29th in February, the year is a leap year. - If February only contains 28 days, it is not a leap year.
3 There is a leap year every 4 years. A typical year lasts 365 days and about 6 hours. In four years, these 6 hours turn into an extra day (6x4 = 24), so there are leap years every 4 years. Add 4 to the last leap year to determine which leap year is next. - For example, 2016 was a leap year, so 2016 + 4 = 2020, which means 2020 will be the next leap year.
clue: Remember that sometimes there is no leap year for 8 years, since a typical year is 365 days 5 hours 48 minutes and 46 seconds (not exactly 6 hours). Therefore, it is better to make calculations rather than relying on the fact that there is a leap year every 4 years.
