Leap Year Calculator

A leap year is a year with 366 days instead of the standard 365. The extra day, February 29 (called a leap day), is added to keep the calendar year synchronized with the astronomical year — the actual time it takes Earth to orbit the sun (approximately 365.2422 days). Without this correction, the calendar would drift about 6 hours per year, and after 100 years, the seasons would be off by 24 days. The concept was introduced by Julius Caesar in 46 BC with the Julian calendar and refined by Pope Gregory XIII in 1582 with the Gregorian calendar we use today.

The Gregorian calendar rule has three conditions checked in order: Step 1: Is the year divisible by 4? If no, it is not a leap year. If yes, go to step 2. Step 2: Is the year divisible by 100? If no, it is a leap year. If yes, go to step 3. Step 3: Is the year divisible by 400? If yes, it is a leap year. If no, it is not. Examples: 2024 is divisible by 4, not by 100 → leap year. 1900 is divisible by 4 and by 100, but not by 400 → not a leap year. 2000 is divisible by 4, 100, and 400 → leap year. This is why the years 1700, 1800, 1900 were not leap years, but 2000 was.

Both 1900 and 2000 are divisible by 100 (century years). The Gregorian calendar rule states that century years are leap years only if they are also divisible by 400. 1900 is divisible by 100 but not by 400 (1900 / 400 = 4.75), so it was not a leap year. 2000 is divisible by both 100 and 400 (2000 / 400 = 5 exactly), so it was a leap year. The next century year is 2100, which will not be a leap year. This exception (removing 3 leap days every 400 years) is what makes the Gregorian calendar accurate to one day in about 3,000 years.

The next leap year after 2026 is 2028. Leap years near our time: 2020, 2024, 2028, 2032, 2036, 2040. They occur every 4 years except at century years not divisible by 400. The next century exception is 2100 — that year will have only 28 days in February. After 2100 the next leap years will be 2104, 2108, etc. The last time a century year was skipped was 1900, and the time before that was 1800 and 1700.

People born on February 29 are called "leaplings" or "leap day babies." They are born roughly 1 in 1,461 days (once per 4-year cycle), making them rare. For legal purposes, most countries treat February 28 or March 1 as their official birthday in non-leap years — this varies by jurisdiction. Famous February 29 birthdays include composer Gioachino Rossini (born 1792) and motivational speaker Tony Robbins (born 1960). Statistically, the probability of being born on February 29 is about 0.07%, compared to about 0.27% for any other day.

February was chosen because it was the last month of the original Roman calendar, which began in March. Romans added days to February because it was the shortest and least important month in their agricultural cycle. When Julius Caesar reformed the calendar in 46 BC, he retained February as the month for the extra day. The Julian calendar added a day to February every 4 years by making it 29 days. The Gregorian reform in 1582 kept February 29 as the leap day but modified the century-year rule. February remains the only month that changes length between years.

In most centuries (like the 1900s or the 2100s), there are 24 leap years. You take the 25 years divisible by 4 in that century and subtract 1 for the century year itself (which is not a leap year unless divisible by 400). In the century that includes a 400-year divisible year (like 2000), there are 25 leap years because the century year itself qualifies. In 400 years, there are exactly 97 leap years (97 extra days), giving an average year length of 365.2425 days, very close to the actual solar year of 365.2422 days.

No — leap seconds and leap years are completely separate concepts. A leap second is an occasional 1-second adjustment added to UTC (Coordinated Universal Time) to account for the irregular slowing of Earth's rotation. Leap seconds have been added 27 times since 1972, most recently in December 2016. They are announced by the International Earth Rotation and Reference Systems Service (IERS) only a few months in advance. A leap year adds one full day (86,400 seconds) every 4 years. Leap seconds add just 1 second unpredictably. The international community voted in 2022 to discontinue leap seconds by 2035.

No. The Gregorian calendar's leap year rules (every 4 years, except century years, except 400-year years) are used in most of the world for civil purposes. The Hebrew calendar adds an entire leap month (Adar I) 7 times every 19 years, making those years 383–385 days long. The Islamic Hijri calendar adds a leap day in the last month 11 times every 30 years. The Ethiopian calendar has 13 months, with the 13th month having 5 days (6 in a leap year). The Coptic calendar also has a 13-month structure. The Persian (Solar Hijri) calendar has its own complex 2,820-year leap cycle that is actually more accurate than the Gregorian calendar.

No, 2026 is not a leap year. 2026 divided by 4 = 506.5 — it is not evenly divisible by 4, so it fails the first test. February 2026 has 28 days. The most recent leap year was 2024, and the next will be 2028. Between any two consecutive leap years that are 4 years apart (excluding century exceptions), every year in between is a common year with 365 days. So 2025, 2026, and 2027 are all common years, and 2028 restores the leap day on February 29.