How do I know if a year is a leap year?

Check whether it divides by 4: if not, it is a common year. If it does, it is a leap year unless it ends in 00; a year ending in 00 is a leap year only when it divides by 400. So 2024 and 2000 are leap years, and 2026 and 1900 are not.

When is the next leap year?

2028: February 29, 2028 is a Tuesday. After it come 2032 and 2036; the next century year, 2100, is not a leap year.

When do people born on February 29 celebrate their birthday?

On February 29 in leap years, and on February 28 or March 1 in the three years between. February 28 keeps the birthday in February; March 1 is the day after February 28, the day a February 29 would have been. The calculator gives the age both ways.

Which day counts legally for a leap day birthday?

It depends on the rule that applies, such as a state law, an agency or a contract, and they differ: some treat a February 29 person as a year older on February 28 in common years, others on March 1. Where a legal age or a deadline depends on it, check that rule; the calculator shows both ages.

How old is someone born on February 29?

Their age in years, like anyone else's: someone born on February 29, 2008 turns 18 in 2026, on February 28 or March 1. In February 29s, the real birthdays, they have had 4 by then (2012, 2016, 2020 and 2024), which is where jokes about leap day birthdays come from.

How rare is a February 29 birthday?

In the calendar, 97 of every 146,097 days in the Gregorian 400-year cycle are February 29s, about 1 day in 1,506. That is the share of days, not of births; birth rates vary through the year.

Why do we have leap years?

Because a year in the seasons is about 365.2422 days, not 365. Adding a day every 4 years gives 365.25, a little too long, so the Gregorian calendar skips 3 leap years every 400 years, averaging 365.2425 days, which stays within a day of the seasons for thousands of years.

Was 2000 a leap year?

Yes. 2000 is a century year, but it divides by 400, so it had a February 29. 1900 did not divide by 400 and was not a leap year, and neither will 2100 be.

Leap Year Calculator

Find out whether any year is a leap year and why, with the leap years before and after it. Born on February 29? Enter the birth year to see how many real birthdays have passed, the age on any date and when the next February 29 comes, with both common-year birthdays named: February 28 and March 1.

Year

No, 2026 is not a leap year

Why:: 2026 is not divisible by 4, so it is not a leap year.
Days in the year:: 365 (February has 28 days)
Leap year before:: 2024
Leap year after:: 2028

How to use the leap year calculator

1
Pick a mode
Check a year, or count a February 29 birthday.
2
Enter the year
Type the year to check, or the year of the leap day birth and the date to count to.
3
Read the answer
See the rule applied, or the real birthdays and the age; copy the link to share it.

How DateMath checks leap years

DateMath applies the Gregorian rule: a year divisible by 4 is a leap year, except a century year, which is a leap year only when it divides by 400. So 2000 was one and 1900 and 2100 are not. For a February 29 birthday, DateMath counts the February 29s after the birth up to the date you pick, and the age in whole years twice: with the birthday on February 28 in common years, the rule the age calculator uses, and on March 1.

The Gregorian calendar. DateMath treats every date as a Gregorian date, with its leap-year rule: a year divisible by 4 is a leap year, except century years not divisible by 400, so 2000 had a February 29 and 2100 will not. Source: Gregorian calendar.

DateMath's date math is tested against more than 100 cases worked out by hand. Every worked example and table on the site is computed with the same code the calculators run, so a page and its calculator can't disagree.

The leap year rule, step by step

The Gregorian calendar, the one in use in the US and almost everywhere else, has three rules. A year is a leap year when:

it divides by 4, such as 2024 or 2028,
unless it divides by 100, such as 1900 or 2100, which are common years,
unless it also divides by 400, such as 2000, which is a leap year after all.

Year	Leap year?	Why
2008	Yes	2008 is divisible by 4 and is not a century year, so it is a leap year.
2024	Yes	2024 is divisible by 4 and is not a century year, so it is a leap year.
2026	No	2026 is not divisible by 4, so it is not a leap year.
2028	Yes	2028 is divisible by 4 and is not a century year, so it is a leap year.
1900	No	1900 is a century year not divisible by 400, so it is not a leap year.
2000	Yes	2000 is divisible by 400, so it is a leap year even though it is a century year.
2100	No	2100 is a century year not divisible by 400, so it is not a leap year.

Was 2008 a leap year? Yes: 2008 is divisible by 4 and is not a century year, so it is a leap year. Its February 29 was a Friday.

Leap years from 1900 to 2100

Every fourth year, with 1900 and 2100 left out: 49 leap years in these two centuries.

1904, 1908, 1912, 1916, 1920, 1924, 1928, 1932, 1936, 1940, 1944, 1948, 1952, 1956, 1960, 1964, 1968, 1972, 1976, 1980, 1984, 1988, 1992, 1996, 2000, 2004, 2008, 2012, 2016, 2020, 2024, 2028, 2032, 2036, 2040, 2044, 2048, 2052, 2056, 2060, 2064, 2068, 2072, 2076, 2080, 2084, 2088, 2092, 2096.

Century years: only those divisible by 400 are leap years
Century year	Leap year?
1600	Yes
1700	No
1800	No
1900	No
2000	Yes
2100	No
2200	No
2400	Yes

Born on February 29: leap year birthdays

Someone born on February 29 has a real birthday only in leap years. In the three years between, the birthday is on February 28 or March 1, depending on the rule you follow, and the calculator's February 29 tab gives the age both ways, the real birthdays so far and the next February 29.

A leap year birthday, worked out

Born on February 29, 2008. On Sunday, February 28, 2027, the person is 19 if the birthday counts on February 28, and still 18 if it counts on March 1. On Monday, March 1, 2027 both rules give 19. By then there have been 4 real birthdays, and the next is Tuesday, February 29, 2028.

Which date counts?

There is no single answer. Many people celebrate on February 28 to keep the birthday in February; others choose March 1, the day a February 29 would have been. Where it matters, such as a legal age, a license or a benefit, the rule of that law, agency or contract decides. The age calculator counts the February 28 birthday; this page shows both.

Why leap years exist

The calendar follows the seasons, and a year of seasons, the tropical year, is about 365.2422 days. A 365-day calendar would drift by about a day every 4 years, so the Julian calendar added a leap day every 4 years, for an average of 365.25 days. That was too long by about 11 minutes a year, so in 1582 the Gregorian reform dropped three leap days every 400 years, for an average of 365.2425 days.

The leap day is February 29 because February was the last month of the early Roman year. The weekday of a date moves two places after a leap day instead of one, which is why the day of the week calculator and the calendar count every February 29.

Frequently asked questions

How do I know if a year is a leap year?: Check whether it divides by 4: if not, it is a common year. If it does, it is a leap year unless it ends in 00; a year ending in 00 is a leap year only when it divides by 400. So 2024 and 2000 are leap years, and 2026 and 1900 are not.
When is the next leap year?: 2028: February 29, 2028 is a Tuesday. After it come 2032 and 2036; the next century year, 2100, is not a leap year.
When do people born on February 29 celebrate their birthday?: On February 29 in leap years, and on February 28 or March 1 in the three years between. February 28 keeps the birthday in February; March 1 is the day after February 28, the day a February 29 would have been. The calculator gives the age both ways.
Which day counts legally for a leap day birthday?: It depends on the rule that applies, such as a state law, an agency or a contract, and they differ: some treat a February 29 person as a year older on February 28 in common years, others on March 1. Where a legal age or a deadline depends on it, check that rule; the calculator shows both ages.
How old is someone born on February 29?: Their age in years, like anyone else's: someone born on February 29, 2008 turns 18 in 2026, on February 28 or March 1. In February 29s, the real birthdays, they have had 4 by then (2012, 2016, 2020 and 2024), which is where jokes about leap day birthdays come from.
How rare is a February 29 birthday?: In the calendar, 97 of every 146,097 days in the Gregorian 400-year cycle are February 29s, about 1 day in 1,506. That is the share of days, not of births; birth rates vary through the year.
Why do we have leap years?: Because a year in the seasons is about 365.2422 days, not 365. Adding a day every 4 years gives 365.25, a little too long, so the Gregorian calendar skips 3 leap years every 400 years, averaging 365.2425 days, which stays within a day of the seasons for thousands of years.
Was 2000 a leap year?: Yes. 2000 is a century year, but it divides by 400, so it had a February 29. 1900 did not divide by 400 and was not a leap year, and neither will 2100 be.