Year a leap year there are 366 days. A leap year occurs every fourth year, or leap year, during which a leap day is intercalated into the month of February. The name "Leap Day" is applied to the added day. The Revised Julian calendar, proposed in 1923 and used in some Eastern Orthodox Churches, has 218 leap years every 900 years, for the average (mean) year length of days, close to the length of the mean tropical year, days (relative error of 9·10). In the year 2800 CE, the Gregorian and Revised Julian calendars will begin to differ by one calendar
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