Leap Year Calculator
Test any year for leap status with the full Gregorian rule — divisible by 4, except centuries unless divisible by 400. Settle the 1900 vs 2000 debate instantly — free, runs locally.
How to Use the Leap Year Calculator
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Frequently Asked Questions
Is 1900 a leap year? Is 2000?
1900 is not (century not divisible by 400); 2000 is (divisible by 400). The rule: divisible by 4, except century years, except centuries divisible by 400 — the tool applies all three clauses.
Why does the century exception exist?
Earth's orbit is 365.2422 days, not 365.25 — the century skip corrects the 11-minute yearly drift. Without it, calendars would slide a full day every 128 years.
Do I need this for birthday planning?
For 29 February birthdays: the tool confirms which years actually contain the date, so milestone parties land on real calendar days.
Does checking years send data anywhere?
No — the check runs entirely in your browser. Nothing leaves your device.
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Last updated October 2026