How does the Hebrew calendar handle leap years?

The Hebrew calendar adds a 13th month in 7 of every 19 years, splitting Adar into Adar I and Adar II. This converter applies the fixed molad-based rules including the four postponements (dehiyyot), so leap years and month lengths are computed correctly.

What is the Anno Mundi (AM) year?

Anno Mundi means "in the year of the world" — the Hebrew calendar counts years from the traditional date of creation. The Gregorian year 2026 corresponds roughly to AM 5786/5787, with the changeover at Rosh Hashanah in the autumn.

Why does the Hebrew year change in autumn, not January?

The Hebrew year begins on Rosh Hashanah (1 Tishrei), which falls in September or October. So a Gregorian date in, say, November has a different AM year than the same Gregorian year in March.

How many days are in a Hebrew month?

Months alternate between 29 and 30 days, and two months (Cheshvan and Kislev) can vary to keep the calendar aligned. A common year runs 353–355 days and a leap year 383–385 days, depending on the postponement rules.

How accurate is this converter?

It uses the standard arithmetic (fixed) Hebrew calendar via the Julian Day Number, matching the calendar in universal civil and religious use. The Hebrew day begins at sunset, so dates after nightfall belong to the following Hebrew day.

Does my date leave my device?

No. The converter is privacy-first — every calculation runs locally in your browser and nothing is sent or stored.

Hebrew Calendar Converter

Hebrew calendar converter

Convert any Gregorian date to the Hebrew (Jewish) calendar. The tool shows the day, the Hebrew month, and the Anno Mundi (AM) year — the count from the traditional date of creation. It is useful for finding yahrzeit (memorial) dates, festival dates, and the Hebrew date on a birth or wedding certificate.

How it works

The converter uses the fixed, arithmetic (molad-based) Hebrew calendar — the same rules in universal civil and religious use, independent of any astronomical observation. It converts your Gregorian date to a Julian Day Number (a continuous count of days), then maps that number onto the Hebrew calendar by determining the AM year, applying the four postponement rules (dehiyyot) that fix when Rosh Hashanah may fall, and counting forward through the months. In a leap year (7 of every 19), the month of Adar splits into Adar I and Adar II. Because the Hebrew day begins at sunset, a civil date near nightfall may map to the following Hebrew day.

Example

The Gregorian date 15 April 2026 converts to roughly 28 Nisan 5786 (AM). The year is 5786 because Rosh Hashanah 5786 fell in autumn 2025, and Nisan is the spring month in which Passover falls.

Hebrew month	Typical season
Tishrei	Sep–Oct (new year)
Nisan	Mar–Apr (Passover)
Av	Jul–Aug
Adar / Adar II	Feb–Mar (Purim)

It is privacy-first: nothing leaves your browser.