Rosh Hashanah Date Calculator

Rosh Hashanah is 1 Tishrei — the first day of the Hebrew year, observed as two days in Israel and the Diaspora alike. It is set by the lunisolar Hebrew calendar using the molad (new moon) and postponement rules (dehiyyot), not by a fixed Gregorian date.

The holiday begins at sunset the evening before the listed Gregorian date. This calculator returns the civil date of 1 Tishrei for the Hebrew year that falls primarily in your chosen Gregorian year — useful for school calendars, travel, and greeting-card planning.

Enter the default Gregorian year 2026 and Rosh Hashanah falls on 2026-09-12, beginning Hebrew year 5787 at sunset on 2026-09-11. On the Gregorian chart Rosh Hashanah usually lands in September or October, drifting earlier or later as leap months accumulate.

Why does Rosh Hashanah move on the Gregorian calendar? The Hebrew calendar adds leap months in a 19-year cycle to keep months aligned with seasons. 1 Tishrei shifts on the solar Gregorian chart even though it is always 1 Tishrei in Hebrew reckoning.

Community synagogue calendars follow the same core Hebrew rules this algorithm uses. Differences you might see are usually about candle-lighting times and city zmanim, not the civil date of 1 Tishrei itself.

Pair with the Passover calculator for 15 Nisan in the same Hebrew year context, or the live days-until-Passover countdown when planning from today. Rosh Hashanah and Passover anchor opposite seasons on the Jewish calendar. Results cite standard molad-based algorithms — confirm candle-lighting locally; Yom Kippur follows on 10 Tishrei ten days after 1 Tishrei in the same Hebrew year.

Hebrew year numbers on greeting cards (5787, 5788, …) advance at Rosh Hashanah, not January 1. Once you have the civil date from this calculator, flip to the Passover tool to see where 15 Nisan falls in the same festival year.