Hebrew date converter: Jewish date today, Hebrew to Gregorian and back

How the Hebrew calendar works

The Hebrew calendar is lunisolar: its months follow the moon, and an extra month every two or three years keeps it in step with the sun. Months have 29 or 30 days. A common year has 12 months and 353, 354 or 355 days, and a leap year has 13 months and 383, 384 or 385 days.

The year number changes at Rosh Hashanah, 1 Tishrei, in September or early October. The year 5787 began on Saturday 12 September 2026, and 5788 begins on Saturday 2 October 2027. Months are traditionally counted from Nisan in spring, which is why Nisan is month 1 even though the year number changes in Tishrei.

The converter computes the calendar from its fixed arithmetic rules, so it works for any year. Our results match Hebcal for every day from 1700 to 2299 CE.

Leap years and Adar I and Adar II

Leap years follow a 19-year cycle. Years 3, 6, 8, 11, 14, 17 and 19 of each cycle are leap years, and a quick test is that (7 × year + 1) mod 19 is less than 7. Recent and coming leap years are 5784, 5787, 5790, 5793, 5795 and 5798.

A leap year inserts a 30-day month, Adar I, before the usual Adar, which is then called Adar II. In 5787, Adar I runs from 8 February to 9 March 2027 and Adar II from 10 March to 7 April 2027. Purim falls in Adar II, on 14 Adar II, which is 23 March 2027.

Birthdays and anniversaries from Adar need care in a leap year, because customs differ on which Adar to use. Ask your rabbi or follow your family’s practice.

Year lengths and the postponement rules

Each year starts from the molad, the calculated mean new moon of Tishrei. Four postponement rules (dehiyyot) can move Rosh Hashanah a day or two later. The most familiar keeps Rosh Hashanah off Sunday, Wednesday and Friday, and another delays it when the molad falls at or after noon. The other two keep every year within the allowed lengths.

The extra or missing day goes into Cheshvan and Kislev. In a 355- or 385-day “complete” year both have 30 days, in a “deficient” year both have 29, and in a regular year Cheshvan has 29 and Kislev 30.

The result panel gives the year length and leap status for any date you convert.

The day begins at sunset

A Hebrew date runs from sunset to the next sunset. On 23 October 2026, the daytime is 12 Cheshvan 5787 and the evening, after sunset, is 13 Cheshvan. Tick “after sunset” when converting the time of an evening birth, death or wedding.

Sunset depends on where you are, and the checkbox does not calculate it. If an event happened close to sunset, check the local sunset time for that day. For the same reason, every Jewish holiday begins on the evening before the date shown in calendars.

Holidays follow from the calendar

Jewish holidays have fixed Hebrew dates, so their Gregorian dates move each year with the length of the Hebrew year. Some examples for 5787:

Because 5787 is a leap year, Pesach 2027 is later than usual, and Rosh Hashanah 5788 is in October. The Jewish calendar 2026 and the Jewish calendar 2027 show every holiday on its day, and the How we calculate page explains the arithmetic.

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