Leap Year CheckerFree online date & time calculator — instant results, no sign-up
Check whether any year is a leap year.
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About the Leap Year Checker
The Leap Year Checker determines whether an entered year is a leap year under the Gregorian calendar rules. It also shows how many days February has and states the divisibility rule used. With the default year of 2026, the result is not a leap year and February has 28 days.
- Year
- The calendar year to check, entered as a whole-number year in the Gregorian calendar; the default is 2026.
Formula and method
L = (Y mod 4 = 0) AND ((Y mod 100 ≠ 0) OR (Y mod 400 = 0)); F = 29 if L is true, otherwise 28. For Y = 2026, Y mod 4 = 2, so L is false and F = 28.
- YThe entered calendar year.
- LA logical value that is true for a leap year and false otherwise.
- FThe number of days in February for the entered year.
- modThe remainder after integer division; a remainder of zero means exact divisibility.
Check whether the year is divisible by 4. If it is not, it is not a leap year. If it is, check the century exception: years divisible by 100 are not leap years unless they are also divisible by 400. Assign February 29 days for a leap year or 28 days otherwise.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Year1970
Results
- Result1970 is not a leap year
- Days in February28
- RuleDivisible by 4, except centuries unless divisible by 400
How to use the Leap Year Checker
- 1Enter the year you want to check in the Year field, or leave the default value of 2026.
- 2Run the check for the entered year.
- 3Read the Result row: for 2026, it states that 2026 is not a leap year.
- 4Read Days in February: for 2026, the value is 28.
- 5Review the Rule row: Divisible by 4, except centuries unless divisible by 400.
Reading your result
Result identifies the entered year and whether it is a leap year. Days in February gives February's length in days for that year. Rule summarizes the Gregorian test: Divisible by 4, except centuries unless divisible by 400. For the default input, the outputs are Result = 2026 is not a leap year; Days in February = 28; Rule = Divisible by 4, except centuries unless divisible by 400.
Limitations
This checker applies Gregorian calendar arithmetic, not the leap-year rules of other calendars. For dates before a location adopted the Gregorian calendar, the result is a backward application of Gregorian rules and may not match the calendar historically used there. Enter a whole-number year; support for BCE years, year zero, and very large year values depends on the calculator's input handling. Leap seconds and time zones do not affect this test.
Common questions
Why is 2026 not a leap year?+
2026 leaves a remainder of 2 when divided by 4, so it fails the first leap-year condition. February therefore has 28 days.
Is being divisible by 4 enough to make a year a leap year?+
Not always. A year divisible by 100 must also be divisible by 400 to qualify as a Gregorian leap year.
What does the century exception mean?+
A century year is a year divisible by 100. The rule excludes those years from leap-year status unless they are also divisible by 400.
Can this checker determine whether a historical year was observed as a leap year locally?+
It determines leap-year status under Gregorian rules only. Historical local practice may differ because regions adopted the Gregorian calendar at different times or used other calendars.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.