The Armenian calendar is based on an invariant year length of 365 days. Because a solar year is about 365.25 days and not 365 days, the correspondence between the Armenian calendar and both the solar year and the Julian calendar slowly drifted over time, shifting across a year of the Julian calendar once in 1,461 calendar years (see Sothic cycle). Thus, the Armenian year 1461 (Gregorian & Julian 2011) completed the first Sothic cycle, and the Armenian Calendar was one year off.
