A fixed feast on the liturgical calendar of the Orthodox Christian Church are those celebrations of holy days that are held on the same calendar date every year. These feasts are distinguished from moveable feasts, such as Pascha and feasts related to it, for which the calendar date varies from year to year.
Fixed feasts are celebrated on the same date for both those who use the Julian (Old) and the Revised Julian (New) calendars but chronologically are thirteen days apart during the twenty-first century. Whereas, movable feasts are celebrated on the two calendars on the same chronological day but on dates that are thirteen days apart.
For certain fixed feasts, mainly those for saints, that are celebrated during the week priests have the prerogative of celebrating the feast during the following weekend.