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Enter a year and click Check Year// determine leap years and find next / previous instantly
Instantly check if any year is a leap year. Find the next and previous leap years, browse leap year sequences, and learn why leap years exist.
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Enter a year and click Check YearType any year between 1 and 9999 in the input field.
Instantly see whether it's a leap year and why.
Jump to the previous or next leap year, or browse the upcoming sequence.
The Leap Year Checker instantly tells you whether any given year is a leap year under the Gregorian calendar — the system used worldwide. It applies all three divisibility rules (by 4, 100, and 400) and shows you the reasoning behind the result.
A year is a leap year if it is divisible by 4 — unless it is also divisible by 100. However, years divisible by 400 are leap years regardless. So 2000 was a leap year, but 1900 was not.
Earth takes approximately 365.2422 days to orbit the Sun. Without adding an extra day roughly every 4 years, our calendar would drift by about 24 days per century, causing seasons to shift over time.
Yes. Although 2000 is divisible by 100, it is also divisible by 400, which overrides the century rule. This made 2000 one of the rarest type of leap years — a century leap year.
No. 1900 is divisible by 100 but not by 400, so it is a common year. This surprises many people who assume all years ending in 00 skip the rule.
The next leap year after 2024 is 2028. Leap years generally occur every 4 years: 2028, 2032, 2036, and so on — until a century year that is not divisible by 400 interrupts the pattern.
People born on February 29 (sometimes called "leaplings") officially celebrate their birthday either on February 28 or March 1 during non-leap years, depending on personal or legal preference.
A leap year is a calendar year containing one extra day — February 29 — making it 366 days long instead of the usual 365. This extra day, called a leap day, is added to keep our modern calendar (the Gregorian calendar) synchronized with Earth's orbit around the Sun.
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The Gregorian calendar uses a precise three-rule system to determine leap years:
This logic means leap years occur 97 times every 400 years — a very precise approximation of the solar year's 365.2425-day length.
Earth's trip around the Sun takes approximately 365 days, 5 hours, 48 minutes, and 45 seconds — about 365.2422 days. If we used a strict 365-day calendar without correction, our calendar would lose roughly one day every 4 years. Over centuries, this drift would shift seasons dramatically: eventually, July (summer in the Northern Hemisphere) would fall in what we consider winter months.
By adding one extra day every 4 years — with the century exceptions — the Gregorian calendar stays accurate to within 26 seconds per year, which amounts to only one day of drift every 3,300 years.
The concept of a leap year predates the Gregorian calendar. Julius Caesar introduced the Julian calendar in 46 BC, which added a leap day every 4 years without exception. While better than previous Roman systems, this over-corrected by about 11 minutes per year. By the 1500s, the Julian calendar had drifted 10 days behind the actual solar year.
Pope Gregory XIII introduced the Gregorian calendar in 1582 to correct this drift. The century rule (years divisible by 100 but not 400 skip the leap year) removed 3 leap days per 400 years, bringing the calendar back into close alignment with the astronomical year. Most of the world now follows the Gregorian calendar, though some cultures maintain parallel traditional calendars.
You can check any year manually using this simple logic:
For example: 2024 ÷ 4 = 506 (no remainder), and 2024 ÷ 100 = 20.24 (has remainder), so 2024 is a leap year. Meanwhile, 2100 ÷ 100 = 21 (no remainder) but 2100 ÷ 400 = 5.25 (has remainder), so 2100 will not be a leap year.
Handling leap years correctly is a classic challenge in software development. Many date-related bugs arise from incorrect leap year logic — famously, some systems failed on February 29, 2000, because developers hadn't tested for the year-400 rule. In code, the standard check is:
(year % 4 == 0 and year % 100 != 0) or (year % 400 == 0)Our Leap Year Checker uses the same authoritative algorithm, verified against the Gregorian calendar standard, so you can trust its results for any year between 1 and 9999.