Is 2026 a leap year? What about 1900 or 2000? Use our free Leap Year Checker to find out instantly, with the exact rule explained.
The Leap Year Rule
A year is a leap year if:
- It is divisible by 4 → leap year
- EXCEPT if divisible by 100 → not a leap year
- EXCEPT if also divisible by 400 → leap year after all
This three-part rule exists because Earth's orbital period is approximately 365.25 days — not an exact 365. Adding an extra day every ~4 years keeps the calendar aligned with the seasons.
Examples
- 2024: Divisible by 4, not by 100 → leap year ✓
- 1900: Divisible by 100 but not by 400 → NOT a leap year ✗
- 2000: Divisible by 400 → leap year ✓
The 1900 exception is the most commonly misunderstood case — many people assume every 4th year is a leap year, but century years break that pattern unless they pass the 400 test.
February 29
The practical effect of a leap year is an extra day — February 29 — added to the calendar. Without it, seasons would slowly drift: after a few centuries, summer would eventually fall in what we now call spring.
Related Tools
For counting days between dates (which automatically handles leap years), see our days between dates calculator guide and Days Between Dates Calculator. For age eligibility, try our age calculator for government forms.
Frequently Asked Questions
What is the leap year rule?
A year is a leap year if divisible by 4, EXCEPT century years (divisible by 100), which are only leap years if also divisible by 400.
Why was 1900 not a leap year but 2000 was?
Both are divisible by 100, but 2000 is also divisible by 400 (making it a leap year), while 1900 is not divisible by 400 (so the century exception applies, making it not a leap year).
Why do we need leap years at all?
Earth's orbit takes approximately 365.25 days, not exactly 365 — without leap years, the calendar would gradually drift out of sync with the seasons over centuries.
How often do leap years occur?
Roughly every 4 years, with the exception of century years not divisible by 400 — making leap years occur 97 times every 400 years rather than exactly 100 times.