Leap year most years that are multiples of 4 are leap years. In each leap year, the month of February has 29 days instead of 28. Adding one extra day in the calendar every four years compensates for the fact that a period of 365 days is shorter than a tropical year by almost 6 hours. Some exceptions to this basic rule are required since the duration of a tropical year is slightly less than 365.25 days. The Gregorian reform modified the Julian calendar's scheme of leap years as follows: Over a period of four centuries, the accumulated error of adding a
Middle-earth calendar the three extra days in every third "yén" (once every 432 years), for an average year length of ≈365.24306 days. In Rivendell, the "loa" began on the spring equinox and was divided into six "months" or seasons, as follows. Five other days, two between "coirë" and "tuilë" and three between "yávië" and "quellë", meant the calendar added up to 365 days. Irregularities were allowed for by adding another three days every twelve years, except the last year of a "yén". The calendar developed by the Men of Middle-earth is called the King's Reckoning, and is in many ways similar to