On which day of Tishrei is Yom Kippur observed?

Yom Kippur is observed on the 10th day of Tishrei. Tishrei is the seventh month of the Hebrew Bible’s calendar and the first month of the civil Jewish year, so Yom Kippur falls during the autumn season in the Gregorian calendar.

The date follows Rosh Hashanah, which begins on 1 Tishrei. Yom Kippur is therefore the culmination of the Ten Days of Repentance, a period traditionally devoted to reflection, repentance, reconciliation, and seeking forgiveness. In Jewish tradition, the holy day begins at sunset on the evening before the daylight date and ends after nightfall.

Its biblical designation is Yom HaKippurim, commonly translated as the Day of Atonement. Observances include a complete fast for healthy adults, extended prayer, confession, and abstention from ordinary work.

A frequent mistake is choosing 9 Tishrei because the fast begins before the daylight date. Jewish days begin at sunset, however, so the observance is associated with 10 Tishrei even though it starts on the preceding evening.