This free online date calculator will check to see if the entered year is leap year according to the Gregorian calendar.
Or, if you enter a starting year and an ending year, the calculator will generate a list of leap years for the given range. And not only will the list include the dates of each leap day, but it will also include the day of the week that each leap day falls on.
And finally, if the start year is a leap year, and a special occasion (birth, wedding, etc.) occurred on February 29th of that year, the calculator will also report how many times you were able to celebrate on the anniversary date.