Check Leap Years
Enter a year to verify the Gregorian leap-year rule, or scan an inclusive range to find every leap year instantly.
A QUICK WALKTHROUGH
How to use this tool
- Choose single year or range mode.
- Enter a whole year, or the start and end years.
- Run the check and review the result locally.
Gregorian rule
A year is a leap year when it is divisible by 4, unless it is a century year; century years are leap years only when divisible by 400. This tool applies that rule to the proleptic Gregorian calendar.
Single years or ranges
Check one year or list every leap year in an inclusive range. Years from 1 through 9999 are accepted, and ranges are limited to 5,000 years so results stay easy to read.
Private browser processing
All validation and calculations happen in your browser. No year or range is sent to a server.
GOOD TO KNOW
Common questions
Why is 1900 not a leap year?
It is divisible by 100 but not by 400, so the century exception applies.
Why is 2000 a leap year?
It is divisible by 400, so it passes the century exception.
Is the range inclusive?
Yes. Both the start and end years are checked.
Does this use historical calendar dates?
No. It applies the proleptic Gregorian rule consistently to years 1 through 9999.