Why does the Hebrew calendar have a leap month instead of a leap day?

The Hebrew calendar is lunisolar: its months track the moon (about 29.5 days each) while the year is kept in step with the solar seasons. Twelve lunar months fall about 11 days short of a solar year, so instead of adding a single leap day like the Gregorian calendar, the Hebrew calendar adds a whole extra month — a second Adar (Adar II) — in 7 of every 19 years (the Metonic cycle). That keeps Passover anchored to spring every year.

Why does the Hebrew day start at sunset, not midnight?

Genesis 1 describes each day of creation as "and there was evening, and there was morning" — evening first. So on the Hebrew calendar a day runs from sunset to the following sunset, not midnight to midnight. This converter works with calendar dates (not clock times), so a Hebrew date shown here corresponds to the civil date that Hebrew day mostly overlaps, matching how these dates are printed on calendars and in reference tables.

What is gematria and why does 15 look different from 16?

Gematria is the traditional system of writing numbers using Hebrew letters as numerals (א=1, ב=2 ... י=10, כ=20, and so on). The numbers 15 and 16 are the one exception: written the ordinary way they'd spell two of the letter-combinations used for God's name, so tradition substitutes ט״ו (9+6=15) and ט״ז (9+7=16) instead of יה and יו.

Yes. Every tool is free to use, with no account and no credit card. The work runs on your device rather than on our servers, which is what keeps it free to run.

Does it work on mobile?

Yes. It runs in current mobile browsers on iOS and Android, with nothing to install.

✡️

Free Hebrew Date Converter

Convert any date between the Gregorian and Hebrew (Jewish) calendars — with Hebrew-numeral (gematria) output, native-script month names, and Adar I/II handled in leap years.

Runs in your browserNo sign-up, no pop-upsNo login requiredFree foreverNo upload

Works offline once loaded

Conversion mode

Gregorian date → Hebrew date

Gregorian date

Born / occurred after sunset

The Hebrew day begins at nightfall, so an evening event belongs to the next Hebrew date.

Holidays by year

Gregorian year

Diaspora dates. Holidays begin at nightfall the evening before.

📅 Everything runs in your browser — no dates are ever sent anywhere or added to the page's web address.

How It Works

The tool implements the Hebrew calendar's molad (mean lunar conjunction) calculation and its four dehiyyot postponement rules directly, converting through a shared day-count so every date lines up exactly with the traditional calendar — no calendar library or browser API required.

1
Pick a direction
Switch between Gregorian → Hebrew and Hebrew → Gregorian with the mode toggle.
2
Enter a date
Use the date picker for a Gregorian date, or type a Hebrew day, month, and year — the month list adjusts automatically for Adar I/II in leap years.
3
Read the result
See the converted date in English transliteration and in Hebrew script with gematria numerals, plus the weekday and leap-year status.
4
Copy what you need
Copy either the English or Hebrew-script form of the result to your clipboard.

Every conversion happens locally in your browser using pure calendar arithmetic. No date you enter is ever sent to a server or written into the page's URL.

Related Tools

🏮

Chinese Lunar Calendar Converter

Convert any date between the Gregorian and Chinese lunar (农历) calendars, with the stem-branch year name, zodiac animal, and correct leap-month handling.

Try it

🎂

Hijri Age Calculator

Calculate your age in the Islamic (Hijri / Umm al-Qura) calendar. Enter a Gregorian or Hijri birth date to see your exact Hijri age in years, months and days, the weekday you were born, and a live countdown to your next Hijri birthday. Free, private, and runs entirely in your browser.

Try it

📅

Bikram Sambat Date Converter

Convert dates between the Nepali Bikram Sambat (BS) calendar and the Gregorian (AD) calendar instantly, with Nepali-script output and weekday lookup.

Try it

Free Hebrew Date Converter

Gregorian date → Hebrew date

Holidays by year

How It Works

Related Tools

Chinese Lunar Calendar Converter

Hijri Age Calculator

Bikram Sambat Date Converter

Frequently Asked Questions