Hebrew Date Converter

The Hebrew calendar is a lunisolar system used for Jewish religious observance: months begin on observed or computed new moons, years receive leap months (Adar II) on a 19-year Metonic cycle, and days start at sunset. This converter translates between Gregorian civil dates and Hebrew dates (year, month, day) for holiday planning, yahrzeit tracking, and genealogy—not for civil court filing deadlines.

Religious versus civil use

Synagogue secretaries schedule Torah readings; families compute yahrzeits; apps show Hebrew dates alongside Gregorian on invitations. Israeli civil life often uses Gregorian for government forms—confirm which calendar your form requires.

Islamic Hijri dates: Islamic date converter. Mayan Long Count: Mayan calendar.

Leap years and month names

Leap years add Adar II; month numbering shifts accordingly. Months alternate 29/30 days with rules set by rabbinic calendar arithmetic (Rosh Hashanah postponements dehiyyot) implemented in astronomical tables—human sighting practices differ historically.

Year numbers count from Creation (Anno Mundi) in display—5786 corresponds to 2026 civil overlap windows; always read both calendars on output.

Sunset and day boundaries

Hebrew days begin at sunset, so an event after dusk belongs to the next Hebrew date even if the Gregorian date unchanged. This converter typically maps civil midnight Gregorian instants unless the UI offers sunset toggle—check form labels for observance-critical bookings.

Pair with holiday reference {CY} for US federal dates separate from Jewish festivals.

Worked Hebrew examples

Example: convert civil Passover prep dates to Hebrew to verify Adar vs Nisan alignment in 2026.

Example: genealogy—translate 1945-05-08 civil to Hebrew for tombstone consistency with family records.

Example: compare lag between days between civil count and Hebrew month lengths when explaining lunisolar drift to students.

Accuracy limits

Software tables follow published arithmetic; ultra-strict halachic communities may follow sighting announcements that shift a day. Document that limitation in apps serving diverse congregations.

Unix logs: Unix timestamp. French Republican: French Republican.

Yahrzeit and community calendars

Synagogue software computes yahrzeits by Hebrew date anniversary, sliding to nearest civil day when necessary. Confirm whether your community observes after sunset when scheduling email reminders—table software may use civil midnight.

Israel publishes Gregorian and Hebrew dates on official forms; diaspora apps may differ in festival second-day observance—label data sources in multilingual products.

Genealogy and civil records

Dual-dated tombstones help descendants reconcile civil birth records with Hebrew memorial dates. When translating, capture both directions for catalog search facets.

Federal civic deadlines remain on US holidays 2026; religious observance uses Hebrew dates separately.

App configuration

Expose Hebrew calendar toggles in settings with clear labels about sunset boundaries and leap months. Default civil Gregorian for travel booking flows to prevent accidental mis-clicks.

Import ICS feeds in civil time even when displaying Hebrew—underlying instants should remain unambiguous for alarms.

Multilingual publishing

Print invitations with Hebrew date secondary unless audience expects primary—always include civil date for travel and hotel bookings.

RTL layout should not flip Gregorian numerals embedded in Hebrew paragraphs.

Healthcare and chaplaincy scheduling

Hospital chaplaincy calendars list Hebrew dates for pastoral visits while EMR systems use Gregorian—convert for interdisciplinary rounds without assuming midnight boundaries for patients observing sunset. Document which calendar drives medication fasting instructions.

Fundraising and event mailers

Nonprofits mailing gala invitations should show Hebrew dates only when audience expects them; always print civil RSVP deadlines for venue contracts. Test sunset-sensitive events with rabbinic advisors before bulk send.

Family history platforms

Genealogy trees storing Hebrew birth dates should also store civil equivalents for duplicate detection across international record sets. Merge algorithms matching only Hebrew strings miss transliteration variants—normalize via Gregorian key.

Travel apps

Flight apps showing Hebrew dates for Israel routes should still gate departure times on Gregorian airport schedules— pilots do not file plans in Hebrew dates alone.

API responses

JSON APIs returning Hebrew dates should include civil ISO sibling fields—mobile clients sort and filter reliably on Gregorian keys.

Cemetery records

Municipal cemeteries digitizing headstones should store Hebrew and Gregorian in separate indexed fields for public search portals.

Nutrition labeling during fasts

Corporate wellness apps referencing minor fasts should cite Hebrew dates with civil tooltips so HR systems do not schedule mandatory lunch meetings on fast days.

School district calendars

Public districts publishing major Jewish holidays should show civil closures with Hebrew footnotes sourced from consistent table software—parents plan childcare faster.

Volunteer coordination

Community kitchens scheduling holiday shifts should publish Hebrew and civil dates on signup forms so volunteers know which legal day they are covering.

Hospital dietary services

Dietary departments coordinating kosher meal trays during festivals need Hebrew dates on kitchen tickets plus civil delivery slots for vendor trucks.

Calendar sync tools

Third-party calendar sync should write Hebrew all-day events on civil midnight with description noting sunset observance when relevant— prevents double bookings across apps. Test one festival week before rolling org-wide to every staff calendar. Document sunset policy in IT runbooks.

Nightfall and calendar dates

Hebrew dates change at nightfall, not civil midnight. Evening events may fall on the next Hebrew date. For lifecycle planning, confirm with a knowledgeable authority when ritual timing matters.

Holiday planning across calendars

Hebrew calendar holidays move against 2026 civil months—verify erev start times with community calendars before booking venue holds. Business deadlines tied to Gregorian quarter-end may conflict with observance days; use business days only after confirming which holidays your firm recognizes.

Genealogy records mixing Julian civil dates with Hebrew birth entries need archivist notes—convert one system at a time and document uncertainty ranges.

Yahrzeit observances sometimes shift when Hebrew evening boundaries cross civil midnight—confirm community rabbinic guidance beyond this converter's arithmetic for 2026 schedules.

Cemetery and archival records

Headstone inscriptions mixing Hebrew and Gregorian dates should footnote which calendar governs legal next-of-kin notices in 2026 probate packets. Digitization projects scanning ledgers must tag calendar system per column before OCR merges rows incorrectly.

Related tools

Converters hub, date tools.