Leap year This makes it easy to convert dates to or from Gregorian. The Thai solar calendar uses the Buddhist Era (BE), but has been synchronized with the Gregorian since AD 1941. From AD 8 the Julian calendar received an extra day added to February in years that are multiples of 4. The Coptic calendar and Ethiopian calendar also add an extra day to the end of the year once every four years before a Julian 29-day February. This rule gives an average year length of 365.25 days. However, it is 11 minutes longer than a tropical year. This means that the
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