A very straight-forward reference post for you today. You generally needn’t memorize the Hebrew dates of most holidays, unless told differently by your beit din. However, you should be able to list these major holidays in chronological order, starting either with Rosh Hashana or Pesach. You may want to compare and contrast with the post about the Hebrew months.
Rosh Hashanah: 1 – 2 Tishrei
Ten Days of Repentance: 1 – 10 Tishrei
Yom Kippur: 10 Tishrei
Succot / Succos: 15 – 21 Tishrei (until 22 Tishrei outside the Land of Israel)
Shemini Atzeret / Atzeres: 22 Tishrei
Simchas /Simcaht Torah: 23 Tishrei (Combined with Shemini Atzeret on 22 Tishrei in the Land of Israel)
Chanukah / Hanukkah: 25 Kislev – 2 or 3 Tevet (Kislev may have either 29 or 30 days)
Tu B’Shvat: 15 Shevat
Purim: 14 Adar
Pesach: 15 – 21 Nissan (until 22 Nissan outside the Land of Israel)
Sefirat HaOmer: The 49 days connecting Pesach and Shavuot.
Lag B’Omer: 33rd day of the Omer, 18 Iyar
Shavuot / Shavuos: 6 Sivan (and 7 Sivan outside the Land of Israel)
Tisha B’Av: 9 Av
FYI, London Beth Din requires one to know Hebrew dates for all festivals and fasts (major and minor).
This is super useful. Taking notes here!