The Armenian calendar is the traditional calendar of Armenia. It was used in Old Armenia during the time before the arrival of Christianity. It is a solar calendar based on the same system as the ancient Egyptian model, having an invariant 365-day year with no leap year rule. As a result, the correspondence between it and the Julian calendar slowly changes over time (such as year 769 on AD 1320 January 1, year 770 on AD 1320 December 31, and year 1032 on AD 1582 October 27 = Gregorian November 6). Some references report that the first month of the year,Navasard, corresponds to the start of Spring in the northern hemisphere, but that was only true from the 9th through 10th centuries.

Armenian year 1461 (Gregorian year 2010–2011) is the last of the great Armenian cycle of 1,461 wandering years which equal 1,460 Julian years (see Sothic cycle). The next year, 1462, begins on 24 July 2012 (Gregorian), 11 July (Julian). Armenian year 1 began on 11 July AD 552 (Julian).

The ancient Armenian year consisted of 12 months of 30 days each, plus a 13th month called epagomenê containing 5 days in a regular year, or 6 days in a leap year.^{[citation needed]}

Years are given in the Armenian alphabet by the letters ԹՎ, a siglum for t’vin "in the year" followed by the year in Armenian numerals. For example, "in the year 1455" would be written ԹՎՌՆԾԵ.

The Armenian month names show influence of the Zoroastrian calendar, and, as noted by Antoine Meillet, Kartvelian influence in two cases. There are different systems for transliterating the names; the forms below are transliterated according to Hübschmann-Meillet-Benveniste system.

The Armenian calendar names the days of the month instead of numbering them – a peculiarity also found in the Avestan calendars. Zoroastrian influence is evident in at least five names.

The epagomenal days are called Aveleacʿ ("superfluous").

The Armenian calendar is a derivative of Zoroastrian changes to Egyptian dates. The first month Navasard is equivalent to the month Choiak (Koyak), however its first day falls on Koyak 4 so that the first of the five (or six) epagum days falls on Egyptian Hatyr 27. This is in contrast to the Zoroastrian calendar where the first month Furvurdeen begins on Koyak 6 because its epagum (Gatha days) begin on Egyptian Koyak 1 as of 388 BC. The month Tir is equal to Egyptian Phamenoth (7th month) as Egyptian midyear; but it is of biblical interest that Armenian midyear (Mareri/Deh) is Egyptian new year month Thoth as if to imply it was at one time the 7th month, in regard of the computation of the Jubilee, and the biblical explanation of how to begin the novel age following the entering into the promised land. Two cycles of 1460 years goes back to August 11, 2369 BC.

Prior to borrowing the Egyptian calendar, the ancient Armenians had a lunar calendar based on a lunation of 28 days.

Together with these alien Zoroastrian, Egyptian, Julian, Gregorian, and ecclesiastical dating schemes, some Armenians still retain the old native calendar usage in which the new year begins at the spring equinox. In the numbering scheme of this solar calendar, the year 1 works out to be 5818–5817 BCE. Hence March 20, 2014 CE marks the start of the Armenian year 7832, and the annual advances repeat one-to-one in tandem upon the spring equinox of each year: March 20, 2015 CE will mark the start of the Armenian year 7833, and so forth.^{[citation needed]}