Leap Year Checker
Instantly check whether any year is a leap year, see why, how many days it has, and the next five leap years.
2024 is a leap year. Divisible by 4 but not by 100 → leap year Days in this year: 366 Next 5 leap years: 2028, 2032, 2036, 2040, 2044
Leap years between two years
Check a list of years
The rule of 4, 100 and 400
Type any year and this tool instantly tells you whether it is a leap year or a common year, and explains exactly which rule applied. It also shows how many days that year has — 366 for a leap year and 365 for a common year — and lists the next five leap years so you can plan ahead. Under the year, "This year" jumps back to the present, and under the range boxes "Quick ranges" — This decade, This century, Last century and the years ahead — fill in a span in one click; the range count then gives the share of the span that is leap years and names the century years in it, each marked leap or common. The Gregorian leap year rule is simple but has a twist: a year is a leap year if it is divisible by 4, except for years divisible by 100, unless they are also divisible by 400. That is why 2000 is a leap year but 1900 is not, and why 2024 is a leap year while 2023 is not. To see how many days each month of a year has, with the month laid out as a calendar, use the Days in Month Calculator.
Why the leap year rule works this way
Earth takes about 365.2422 days to orbit the Sun, so adding one extra day every four years keeps the calendar roughly aligned with the seasons. But four years of quarter-days slightly overshoots, so the Gregorian calendar skips the leap day in three out of every four century years — keeping years divisible by 400 like 1600 and 2000, but dropping 1700, 1800 and 1900. This 97-leap-days-per-400-years scheme keeps the calendar accurate to within about one day every 3,000 years. Everything here is computed locally in your browser, so you can check as many years as you like without limits.
Frequently asked questions
Why is 2000 a leap year but 1900 is not?
Both are divisible by 4 and by 100, which by itself would make them common years. The extra rule says century years are leap years only when also divisible by 400. 2000 is divisible by 400, so it is a leap year; 1900 is not divisible by 400, so it is a common year.
How many days are in a leap year?
A leap year has 366 days because February gains a 29th day. A common (non-leap) year has 365 days. This tool shows the exact day count for whichever year you enter.
What about years before 1582?
The tool applies the Gregorian rule to every year. For years before 1582 that is the proleptic Gregorian calendar — the rule run backwards over years that were actually counted by the Julian calendar, where every fourth year was a leap year with no century exception. So 1500 was a leap year when it happened, even though this tool reports it as a common year; historians usually keep Julian dates as written, so check which calendar a source uses before relying on the answer.
Can I list every leap year in a range, or check many years at once?
Yes. “Leap years between two years” counts and lists every leap year from a start year to an end year, and “Check a list of years” answers each year you paste, one per line, flagging anything that is not a whole year.
Are there shortcuts for common ranges, and what does the range count include?
Yes. "This year" puts the present year back in the box, and "Quick ranges" fill in This decade, This century, Last century or the years ahead, worked out from the year it is when you press them. The count then says what share of the span is leap years and names its century years, each marked leap or common and why.
Can I save the list of leap years as a file?
Yes. Beside the Copy buttons, “Download leap years in range” saves the range answer and “Download list answers” saves the answers to a pasted list, each as a text file with the same text Copy puts on the clipboard. The single-year answer is short enough that it stays Copy-only.