Why Yom Kippur’s Date Changes Every Year

Yom Kippur, or the Day of Atonement, is the holiest day on the Jewish calendar. The solemn occasion marks the end of an annual 10-day period of reflection, known as the Days of Awe, that begins with Rosh Hashanah, the Jewish New Year. During this time, Jewish tradition holds that God determines each person’s fate for the year ahead. On Yom Kippur, God’s judgment is finalized, and that fate is sealed.

Observant Jews spend Yom Kippur in prayer, seeking repentance and forgiveness of their sins, attending special religious services and abstaining from food, drink and other physical pleasures.

Exactly when Jews practice these customs changes from year to year because the date of Yom Kippur shifts on the Gregorian calendar. Here’s what to know about the holiday’s timing, length and first observance.

Like many holidays, Yom Kippur is observed for one day—about 25 hours, to be exact. However, a day on the Jewish calendar begins in the evening rather than at midnight. This means that Yom Kippur spans two days on the Gregorian calendar, starting before sundown and ending at nightfall the next day.

Yom Kippur takes place from sundown on September 20, 2026, to nightfall on September 21, 2026. On the Jewish calendar, the date remains fixed as the 10th of Tishrei. Tishrei is the seventh month of the Jewish calendar year, which always occurs in September or October on the Gregorian calendar.

Yom Kippur’s timing is dictated by the Jewish lunisolar calendar, which typically has 12 months that last either 29 or 30 days. Because the Jewish and Gregorian calendars do not align, the holiday’s date changes on the Gregorian calendar from year to year. The earliest possible date is September 14, and the latest possible date is October 14.

The first Yom Kippur occurred in ancient times, though sources differ on the exact year. Traditionally, the inaugural holiday is said to have taken place after the people of Israel left Egypt, perhaps in 1440 B.C.

However, Jewish historian Elon Gilad has written that the first Yom Kippur might have occurred much later given that Nehemiah 8 from the Hebrew Bible, which describes observances during the seventh month of the Jewish calendar, makes no mention of the holiday. Gilad argues the first Yom Kippur was observed by the third century B.C. based on a Greek translation of the Torah in one of the earliest known documents that mentions the holiday.