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Inputs remain on your device.
Leap Year Calculator
Check Gregorian leap-year rules and the number of days in a year.
Calculations happen locally; dates and time zones are not transmitted.
How to use the leap year calculator
- 1
Enter the required dates, times or options.
- 2
Select Calculate to run the operation locally.
- 3
Review and copy each format or print the result.
Calendar accuracy in your browser
Explicit rules
Validates ranges, leap years and month changes.
International formats
Uses Intl and IANA to localize results.
Frequently asked questions
What is a leap year?
A Gregorian leap year is divisible by 4, except centuries unless divisible by 400.
Are my dates sent to a server?
No. Every operation runs in your browser.
Which calendar is used?
It uses the Gregorian calendar and dates from years 1 through 9999.