Enter any year to find out if it is a leap year.
What Makes a Leap Year?
A leap year is a calendar year that has 366 days instead of the usual 365 — the extra day being February 29. Leap years exist to keep our calendar synchronized with the Earth's orbit around the sun, which takes approximately 365.2422 days (not a whole number). Without periodic corrections, our calendar would slowly drift out of alignment with the astronomical seasons.
The rule for determining a leap year in the Gregorian calendar is: a year is a leap year if it is divisible by 4, except for century years (years ending in 00), which must be divisible by 400 to be a leap year. This means 2000 was a leap year, but 1900 was not — and 2100 will not be either. The leap year checker on daycalctools.com applies this rule instantly for any year you enter.
Recent and Upcoming Leap Years
Here is a quick reference for leap years around the current decade:
- 2020 — leap year (divisible by 4)
- 2024 — leap year (divisible by 4)
- 2028 — leap year (divisible by 4)
- 2032 — leap year (divisible by 4)
- 2100 — NOT a leap year (century year not divisible by 400)
Frequently Asked Questions
Why do we have leap years?
The Earth takes about 365.2422 days to orbit the sun. A standard calendar year of 365 days falls short by roughly 6 hours. Over four years, this adds up to nearly one full day. Adding February 29 every four years corrects this accumulated difference, keeping the calendar aligned with the seasons. Without leap years, the calendar would drift by about 24 days per century, and eventually December would occur in summer (in the Northern Hemisphere).
Why are century years a special case?
The extra day every 4 years overcorrects slightly — it adds too much time. To compensate, century years (1800, 1900, 2000, 2100, etc.) are skipped as leap years, unless they are divisible by 400. Skipping century years removes 3 leap days every 400 years, which keeps the calendar accurate to within 26 seconds per year — accurate enough to last for thousands of years without further adjustment.
What happens to people born on February 29?
People born on February 29 (called "leaplings" or "leap day babies") typically celebrate their birthday on either February 28 or March 1 in non-leap years. Legally, the interpretation varies by country — in some jurisdictions, their official birthday in a non-leap year is March 1; in others, it is February 28.
How many days are in a leap year?
A leap year has 366 days — the extra day is February 29. All other months retain their standard lengths: January (31), February (29 in a leap year), March (31), April (30), May (31), June (30), July (31), August (31), September (30), October (31), November (30), December (31).
How far back and forward does the leap year checker work?
The tool applies the Gregorian calendar rules to any year you enter, whether in the past or future. Note that the Gregorian calendar was introduced in 1582, replacing the Julian calendar which had a simpler (and slightly less accurate) leap year rule of every 4 years without the century exception. For years before 1582, the result reflects what the Gregorian rule would give, not the historical Julian calendar rule.