Leap Year Calculator
Enter a year to find out whether it has 365 or 366 days.
A leap year contains an extra calendar day in February. The Gregorian calendar uses a rule based on divisibility by 4, 100 and 400 to determine leap years.
Enter a year and calculate whether it is a leap year. The result also shows the total number of days in that year.
Enter the values you want to compare or calculate, then use the result as a practical reference. The calculator runs in your browser and does not require an account.
This tool also fits into a wider set of practical utilities. Depending on what you are trying to calculate or measure next, you can continue with Days in a Month Calculator, Days Passed This Year, Days Remaining This Year and Day of the Week Calculator. For the complete collection, visit the utility tools homepage and choose another tool when your task changes.
How to use this calculator
- Enter your values. Select the dates or numbers required by the calculator.
- Check the inputs. Make sure the dates are in the order and range you intend to calculate.
- Calculate the result. The result appears instantly in the calculator above without submitting a form.
- Use the result. Apply the result to your schedule, deadline, planning or date calculation.
How the calculation works
Enter the values you want to compare or calculate, then use the result as a practical reference. The calculator runs in your browser and does not require an account. The calculation is performed locally in your browser, so the page can return a result immediately after you change the inputs.
Things to know about date calculations
Calendar calculations can differ depending on whether a result is treated as an elapsed interval or an inclusive count. This site uses clear calendar-date rules and explains important assumptions where they affect the result. Business-day calculations on this page exclude weekends but do not automatically remove public holidays.
Frequently asked questions
What makes a year a leap year?
A Gregorian year is normally a leap year when it is divisible by 4, except century years that are not divisible by 400.
How many days are in a leap year?
A leap year has 366 days, including February 29.