from the series of short articles about calendars
The Armenian calendar is a Julian calendar, where no leap years are taken into account. This calendar started on July 11th of 552 AD, by virtue of the separation of the Armenian Apostolic Church from the Chalcedonian Churches by the Monophysite schism. The Armenian priests do not admit the term ‘monophysitism’ (only one nature) and they prefer to use the term ‘miaphysitism’ (one nature), since they do not overestimate the divine or the human nature of Christ, but they consider both of them united in one nature.
The normal Julian calendar puts one day every 4th year. The tetrad of years is 365-365-365-366 years, giving an average 365¼ days. On the other hand the Armenian years are always of 365 days. The Armenian year is the same as the year of the Egyptian Calendar of the former times before the Julian reformation. Thus the Armenian calendar drifts slowly over time to both the Julian and the currently used more accurate Gregorian calendar. This shift results to an alignment between Armenian and Julian calendar every 1460 Julian years or 1461 Armenian/ Egyptian years (with one additional whole year in the Armenian calendar due to the gradual shift along the years). The Armenian year 1 was 552 AD and more accurately 552/553 AD since the start of the Armenian year occurs on July 11th, thus it is extended also in the next year. After the pass of 1460 Julian years the Armenian year started again on July 11th (Old Style Calendar) or equivalently July 24th in the currently used New Style Gregorian Calendar. The couple of the Julian/ Gregorian years then was 2012/2013 AD, while the Armenian, starting on July 24th 2013 AD was 1462, due to the conclusion of 1461 Armenian years in the duration of 1460 Julian years.
An analytical expression of the Armenian date includes ancient name of Day of week, Christian name of Day of week, named Day of month, Date, Month, Armenian Year number (with Armenian 1 corresponding to 552/553 AD), as well as the religious feasts.
The Armenian calendar is divided into 12 months of 30 days each, plus an additional (epagomenal) five days month, called aweleacʿ ("superfluous").