When does a Hebrew day begin?

At sunset the evening before, not at midnight — so a Hebrew-dated event's observance traditionally starts the prior evening, even though the calendar date matches the following daytime.

Is this the same calendar Israel uses officially?

Israel uses the Gregorian calendar for civil/administrative purposes and the Hebrew calendar for religious and some official Jewish-context purposes (like this calendar shown here) — both are in everyday use.

How accurate is this converter?

Verified against 2 independently-published, real-world reference dates before shipping (see the formula note above) — both matched exactly.

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Jewish Tools

Hebrew Calendar Converter

Convert between the Gregorian and Hebrew (Jewish) lunisolar calendars.

🔒 Runs entirely in your browser — nothing here is ever uploaded

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About the Hebrew Calendar Converter

Converts dates between the Gregorian calendar and the Hebrew (Jewish) lunisolar calendar, in either direction.

100% Free Runs in Your Browser No Sign-Up Required

How to use it

Choose a direction: Gregorian to Hebrew, or Hebrew to Gregorian.
Enter the date (or Hebrew year, month, and day).
Read the converted date.

Formula

Uses the `jewish-date` library's deterministic lunisolar calculation (the standard fixed arithmetic Hebrew calendar in use since the 4th century CE), verified against 2 independently-published real dates before shipping: October 7, 2023 (widely reported as Shemini Atzeret/Simchat Torah that year) converts to 22 Tishrei 5784, matching exactly; and Purim 2026 is independently published as ending nightfall March 3, 2026, matching this tool's 14 Adar 5786 → March 3, 2026 exactly.

Worked example

October 7, 2023 converts to 22 Tishrei 5784.

Interpreting your result

The Hebrew calendar adds a leap month (Adar II) roughly every 2-3 years on a fixed 19-year cycle, keeping its lunar months aligned with the solar year. A Hebrew day traditionally begins at the preceding sunset, so the Gregorian date shown corresponds to that Hebrew date's daytime portion, not the evening before — observance of a Hebrew-dated event actually starts the prior evening.

Recommendations

• For an event that must fall on a specific Hebrew date every year (like a holiday, Yahrzeit, or Bar/Bat Mitzvah), use this site's dedicated calculators for those — they handle the year-to-year date drift automatically.

Frequently asked questions

To keep its lunar months aligned with the solar year — 12 lunar months (about 354 days) drift about 11 days short of a solar year each year, so a leap month (Adar II) is added in 7 of every 19 years on a fixed, predictable cycle.