Ethiopian calendar is based on the old Alexandrian or Coptic calendar, but like the Julian calendar it adds leap day every four year without exception.
Ethiopian calendar has twelve months of 30 days each and a thirteenth month with five days; the thirteenth month(Pagume) will have six days every four years. Ethiopian new year usually falls on either September 11 or 12.
Name of the months: Meskerem, Tikimit, Hidar, Tahisas, Tir, Yekatit, Megabit, Meyazya, Ginbot, Sene, Hamle, Nehase, Pagume
Name of the days: Segno(Monday), Maksegno(Tuesday), Erob(Wednesday), Hamus(Thursday), Arb(Friday), Kidame(Saturday), Ehud(Sunday)
This app displays Ethiopian calendar with official Ethiopian holidays and optional religious fasting days. The app also supports displaying geez numerals.
Enjoy.