What this calculation means
The Gregorian rule is more precise than “every four years.” A year divisible by 4 is normally a leap year, century years divisible by 100 are not, and years divisible by 400 become leap years again.
How to use it
Step 1
Enter a whole Gregorian year.
Step 2
Read whether it is a common or leap year.
Step 3
Check the previous and next leap year for planning around February 29.
Useful for
- • February date validation
- • Calendar and software testing
- • Long-range schedule planning
Limits to keep visible
- • This calculator applies the Gregorian calendar rule. Historical calendars and local adoption dates can differ.
- • A year value is calendar context, not a timestamp or time-zone calculation.
Frequently asked questions
Was 2000 a leap year?
Yes. It is divisible by 400.
Was 1900 a leap year?
No. It is divisible by 100 but not by 400.
Why do leap years exist?
The extra day keeps the civil calendar aligned more closely with Earth’s approximately 365.242-day orbital year.