Leap Year Calculator
Enter any year to find out whether it is a leap year, how many days it contains, and when the nearest leap years are. Switch to range mode to list every leap year between two years and see the count at a glance. Results update instantly as you type.
What is a leap year?
A leap year is a calendar year that contains one extra day - February 29 - giving it 366 days instead of the usual 365. This extra day compensates for the fact that Earth takes approximately 365.2422 days to orbit the Sun. Without the periodic correction, each calendar year would run about 6 hours short of a full solar year, and over centuries the calendar would drift out of sync with the seasons. The Gregorian calendar, introduced in 1582 and now used worldwide, adds a leap day roughly every four years to keep the civil calendar aligned with the astronomical year.
How do you tell if a year is a leap year?
Apply three rules in order. First, if a year is NOT divisible by 4, it is a common year - full stop. Second, if it IS divisible by 4 but NOT by 100, it is a leap year. Third, if it is divisible by 100 (a "century year"), it is only a leap year when it is also divisible by 400. This means 1700, 1800, and 1900 were NOT leap years even though each follows a multiple of 4, while 2000 was a leap year because 2000 / 400 = 5 exactly. The next century that follows this pattern is 2100, which will be a common year despite being divisible by 4.
Why does February get the extra day?
February is the shortest month because of how the ancient Roman calendar was restructured by Julius Caesar and later Augustus. When Caesar introduced the Julian calendar in 46 BCE, he distributed 365 days across twelve months and gave February - the last month of the Roman year - the remaining 28 days. When Augustus added a 31st day to August to match July (named for Julius Caesar), a day was borrowed from February, leaving it with 28. The leap day is appended to the end of February, creating February 29, so existing month boundaries are not disturbed.
Leap year examples and edge cases
The year 2000 is the most commonly cited "special" leap year: it is a century year divisible by 400, and many software programs that did not account for this rule incorrectly predicted February 28 as the last day. The years 1900, 1800, and 1700 are examples of century years that were NOT leap years. People born on February 29 - sometimes called "leaplings" or "leap-day babies" - officially celebrate their birthday on February 28 or March 1 in non-leap years, depending on the jurisdiction. Some national regulations specify which date is used for age calculations, insurance, and legal purposes.
Leap Year Rules at a Glance
| Rule | Condition | Result |
|---|---|---|
| Rule 1 | Year NOT divisible by 4 | Common year (365 days) |
| Rule 2 | Year divisible by 4 but NOT by 100 | Leap year (366 days) |
| Rule 3a | Year divisible by 100 but NOT by 400 | Common year (365 days) |
| Rule 3b | Year divisible by 400 | Leap year (366 days) |
The three-step test used by the Gregorian calendar. Apply the rules in order - only step 3 overrides step 2.
Frequently asked questions
When is the next leap year?
After 2024, the next leap year is 2028. Leap years fall every four years as long as the year is not a century year that falls outside the 400-year rule. You can use the single-year mode above to check any specific year, or the range mode to list every leap year over a span of years.
Why is a century year sometimes NOT a leap year?
The Julian calendar added a leap day every four years with no exceptions, which overcompensated slightly. The Gregorian reform in 1582 corrected this by skipping the leap day in century years (years ending in "00") unless that century year is also divisible by 400. This drops 3 leap years every 400 years, making the average year length 365.2425 days - very close to the actual solar year of 365.2422 days.
How many leap years are there in a 100-year century?
In most centuries there are 24 leap years. For example, 1901-2000 had 25 leap years because 2000 is divisible by 400. In centuries where the final year is a century year that is NOT divisible by 400 (like 1800 or 1900), there are only 24. Over any 400-year cycle in the Gregorian calendar there are exactly 97 leap years.
What happens to people born on February 29?
People born on February 29 (sometimes called leaplings) celebrate their birthday on February 28 or March 1 in common years. Most countries default to February 28 for legal age calculations; some use March 1. If a contract or deadline is stated "on your birthday each year," the specific date should be clarified in the agreement.
Is the year 2100 a leap year?
No. The year 2100 is divisible by 100 but NOT by 400, so under the Gregorian calendar it is a common year with 365 days. The last century leap year was 2000; the next will be 2400.
How many days are in a leap year?
A leap year has 366 days: the usual 365 plus February 29. The extra day falls at the end of February and is called the "intercalary day" or "leap day."
Does every calendar system have leap years?
No. The concept of an intercalary day exists in many but not all calendars. The Islamic (Hijri) calendar is a purely lunar calendar that makes no solar correction, so it drifts about 11 days per year relative to the Gregorian calendar. The Hebrew and Chinese lunisolar calendars insert an entire leap month rather than a single day. The Ethiopian calendar adds a 13th month of 5 or 6 days at the end of the year.